LCOV - code coverage report
Current view: top level - contrib/postgres_fdw - postgres_fdw.c (source / functions) Hit Total Coverage
Test: PostgreSQL 17devel Lines: 2093 2265 92.4 %
Date: 2024-03-28 18:11:13 Functions: 88 89 98.9 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * postgres_fdw.c
       4             :  *        Foreign-data wrapper for remote PostgreSQL servers
       5             :  *
       6             :  * Portions Copyright (c) 2012-2024, PostgreSQL Global Development Group
       7             :  *
       8             :  * IDENTIFICATION
       9             :  *        contrib/postgres_fdw/postgres_fdw.c
      10             :  *
      11             :  *-------------------------------------------------------------------------
      12             :  */
      13             : #include "postgres.h"
      14             : 
      15             : #include <limits.h>
      16             : 
      17             : #include "access/htup_details.h"
      18             : #include "access/sysattr.h"
      19             : #include "access/table.h"
      20             : #include "catalog/pg_class.h"
      21             : #include "catalog/pg_opfamily.h"
      22             : #include "commands/defrem.h"
      23             : #include "commands/explain.h"
      24             : #include "commands/vacuum.h"
      25             : #include "executor/execAsync.h"
      26             : #include "foreign/fdwapi.h"
      27             : #include "funcapi.h"
      28             : #include "miscadmin.h"
      29             : #include "nodes/makefuncs.h"
      30             : #include "nodes/nodeFuncs.h"
      31             : #include "optimizer/appendinfo.h"
      32             : #include "optimizer/clauses.h"
      33             : #include "optimizer/cost.h"
      34             : #include "optimizer/inherit.h"
      35             : #include "optimizer/optimizer.h"
      36             : #include "optimizer/pathnode.h"
      37             : #include "optimizer/paths.h"
      38             : #include "optimizer/planmain.h"
      39             : #include "optimizer/prep.h"
      40             : #include "optimizer/restrictinfo.h"
      41             : #include "optimizer/tlist.h"
      42             : #include "parser/parsetree.h"
      43             : #include "postgres_fdw.h"
      44             : #include "storage/latch.h"
      45             : #include "utils/builtins.h"
      46             : #include "utils/float.h"
      47             : #include "utils/guc.h"
      48             : #include "utils/lsyscache.h"
      49             : #include "utils/memutils.h"
      50             : #include "utils/rel.h"
      51             : #include "utils/sampling.h"
      52             : #include "utils/selfuncs.h"
      53             : 
      54           8 : PG_MODULE_MAGIC;
      55             : 
      56             : /* Default CPU cost to start up a foreign query. */
      57             : #define DEFAULT_FDW_STARTUP_COST    100.0
      58             : 
      59             : /* Default CPU cost to process 1 row (above and beyond cpu_tuple_cost). */
      60             : #define DEFAULT_FDW_TUPLE_COST      0.2
      61             : 
      62             : /* If no remote estimates, assume a sort costs 20% extra */
      63             : #define DEFAULT_FDW_SORT_MULTIPLIER 1.2
      64             : 
      65             : /*
      66             :  * Indexes of FDW-private information stored in fdw_private lists.
      67             :  *
      68             :  * These items are indexed with the enum FdwScanPrivateIndex, so an item
      69             :  * can be fetched with list_nth().  For example, to get the SELECT statement:
      70             :  *      sql = strVal(list_nth(fdw_private, FdwScanPrivateSelectSql));
      71             :  */
      72             : enum FdwScanPrivateIndex
      73             : {
      74             :     /* SQL statement to execute remotely (as a String node) */
      75             :     FdwScanPrivateSelectSql,
      76             :     /* Integer list of attribute numbers retrieved by the SELECT */
      77             :     FdwScanPrivateRetrievedAttrs,
      78             :     /* Integer representing the desired fetch_size */
      79             :     FdwScanPrivateFetchSize,
      80             : 
      81             :     /*
      82             :      * String describing join i.e. names of relations being joined and types
      83             :      * of join, added when the scan is join
      84             :      */
      85             :     FdwScanPrivateRelations,
      86             : };
      87             : 
      88             : /*
      89             :  * Similarly, this enum describes what's kept in the fdw_private list for
      90             :  * a ModifyTable node referencing a postgres_fdw foreign table.  We store:
      91             :  *
      92             :  * 1) INSERT/UPDATE/DELETE statement text to be sent to the remote server
      93             :  * 2) Integer list of target attribute numbers for INSERT/UPDATE
      94             :  *    (NIL for a DELETE)
      95             :  * 3) Length till the end of VALUES clause for INSERT
      96             :  *    (-1 for a DELETE/UPDATE)
      97             :  * 4) Boolean flag showing if the remote query has a RETURNING clause
      98             :  * 5) Integer list of attribute numbers retrieved by RETURNING, if any
      99             :  */
     100             : enum FdwModifyPrivateIndex
     101             : {
     102             :     /* SQL statement to execute remotely (as a String node) */
     103             :     FdwModifyPrivateUpdateSql,
     104             :     /* Integer list of target attribute numbers for INSERT/UPDATE */
     105             :     FdwModifyPrivateTargetAttnums,
     106             :     /* Length till the end of VALUES clause (as an Integer node) */
     107             :     FdwModifyPrivateLen,
     108             :     /* has-returning flag (as a Boolean node) */
     109             :     FdwModifyPrivateHasReturning,
     110             :     /* Integer list of attribute numbers retrieved by RETURNING */
     111             :     FdwModifyPrivateRetrievedAttrs,
     112             : };
     113             : 
     114             : /*
     115             :  * Similarly, this enum describes what's kept in the fdw_private list for
     116             :  * a ForeignScan node that modifies a foreign table directly.  We store:
     117             :  *
     118             :  * 1) UPDATE/DELETE statement text to be sent to the remote server
     119             :  * 2) Boolean flag showing if the remote query has a RETURNING clause
     120             :  * 3) Integer list of attribute numbers retrieved by RETURNING, if any
     121             :  * 4) Boolean flag showing if we set the command es_processed
     122             :  */
     123             : enum FdwDirectModifyPrivateIndex
     124             : {
     125             :     /* SQL statement to execute remotely (as a String node) */
     126             :     FdwDirectModifyPrivateUpdateSql,
     127             :     /* has-returning flag (as a Boolean node) */
     128             :     FdwDirectModifyPrivateHasReturning,
     129             :     /* Integer list of attribute numbers retrieved by RETURNING */
     130             :     FdwDirectModifyPrivateRetrievedAttrs,
     131             :     /* set-processed flag (as a Boolean node) */
     132             :     FdwDirectModifyPrivateSetProcessed,
     133             : };
     134             : 
     135             : /*
     136             :  * Execution state of a foreign scan using postgres_fdw.
     137             :  */
     138             : typedef struct PgFdwScanState
     139             : {
     140             :     Relation    rel;            /* relcache entry for the foreign table. NULL
     141             :                                  * for a foreign join scan. */
     142             :     TupleDesc   tupdesc;        /* tuple descriptor of scan */
     143             :     AttInMetadata *attinmeta;   /* attribute datatype conversion metadata */
     144             : 
     145             :     /* extracted fdw_private data */
     146             :     char       *query;          /* text of SELECT command */
     147             :     List       *retrieved_attrs;    /* list of retrieved attribute numbers */
     148             : 
     149             :     /* for remote query execution */
     150             :     PGconn     *conn;           /* connection for the scan */
     151             :     PgFdwConnState *conn_state; /* extra per-connection state */
     152             :     unsigned int cursor_number; /* quasi-unique ID for my cursor */
     153             :     bool        cursor_exists;  /* have we created the cursor? */
     154             :     int         numParams;      /* number of parameters passed to query */
     155             :     FmgrInfo   *param_flinfo;   /* output conversion functions for them */
     156             :     List       *param_exprs;    /* executable expressions for param values */
     157             :     const char **param_values;  /* textual values of query parameters */
     158             : 
     159             :     /* for storing result tuples */
     160             :     HeapTuple  *tuples;         /* array of currently-retrieved tuples */
     161             :     int         num_tuples;     /* # of tuples in array */
     162             :     int         next_tuple;     /* index of next one to return */
     163             : 
     164             :     /* batch-level state, for optimizing rewinds and avoiding useless fetch */
     165             :     int         fetch_ct_2;     /* Min(# of fetches done, 2) */
     166             :     bool        eof_reached;    /* true if last fetch reached EOF */
     167             : 
     168             :     /* for asynchronous execution */
     169             :     bool        async_capable;  /* engage asynchronous-capable logic? */
     170             : 
     171             :     /* working memory contexts */
     172             :     MemoryContext batch_cxt;    /* context holding current batch of tuples */
     173             :     MemoryContext temp_cxt;     /* context for per-tuple temporary data */
     174             : 
     175             :     int         fetch_size;     /* number of tuples per fetch */
     176             : } PgFdwScanState;
     177             : 
     178             : /*
     179             :  * Execution state of a foreign insert/update/delete operation.
     180             :  */
     181             : typedef struct PgFdwModifyState
     182             : {
     183             :     Relation    rel;            /* relcache entry for the foreign table */
     184             :     AttInMetadata *attinmeta;   /* attribute datatype conversion metadata */
     185             : 
     186             :     /* for remote query execution */
     187             :     PGconn     *conn;           /* connection for the scan */
     188             :     PgFdwConnState *conn_state; /* extra per-connection state */
     189             :     char       *p_name;         /* name of prepared statement, if created */
     190             : 
     191             :     /* extracted fdw_private data */
     192             :     char       *query;          /* text of INSERT/UPDATE/DELETE command */
     193             :     char       *orig_query;     /* original text of INSERT command */
     194             :     List       *target_attrs;   /* list of target attribute numbers */
     195             :     int         values_end;     /* length up to the end of VALUES */
     196             :     int         batch_size;     /* value of FDW option "batch_size" */
     197             :     bool        has_returning;  /* is there a RETURNING clause? */
     198             :     List       *retrieved_attrs;    /* attr numbers retrieved by RETURNING */
     199             : 
     200             :     /* info about parameters for prepared statement */
     201             :     AttrNumber  ctidAttno;      /* attnum of input resjunk ctid column */
     202             :     int         p_nums;         /* number of parameters to transmit */
     203             :     FmgrInfo   *p_flinfo;       /* output conversion functions for them */
     204             : 
     205             :     /* batch operation stuff */
     206             :     int         num_slots;      /* number of slots to insert */
     207             : 
     208             :     /* working memory context */
     209             :     MemoryContext temp_cxt;     /* context for per-tuple temporary data */
     210             : 
     211             :     /* for update row movement if subplan result rel */
     212             :     struct PgFdwModifyState *aux_fmstate;   /* foreign-insert state, if
     213             :                                              * created */
     214             : } PgFdwModifyState;
     215             : 
     216             : /*
     217             :  * Execution state of a foreign scan that modifies a foreign table directly.
     218             :  */
     219             : typedef struct PgFdwDirectModifyState
     220             : {
     221             :     Relation    rel;            /* relcache entry for the foreign table */
     222             :     AttInMetadata *attinmeta;   /* attribute datatype conversion metadata */
     223             : 
     224             :     /* extracted fdw_private data */
     225             :     char       *query;          /* text of UPDATE/DELETE command */
     226             :     bool        has_returning;  /* is there a RETURNING clause? */
     227             :     List       *retrieved_attrs;    /* attr numbers retrieved by RETURNING */
     228             :     bool        set_processed;  /* do we set the command es_processed? */
     229             : 
     230             :     /* for remote query execution */
     231             :     PGconn     *conn;           /* connection for the update */
     232             :     PgFdwConnState *conn_state; /* extra per-connection state */
     233             :     int         numParams;      /* number of parameters passed to query */
     234             :     FmgrInfo   *param_flinfo;   /* output conversion functions for them */
     235             :     List       *param_exprs;    /* executable expressions for param values */
     236             :     const char **param_values;  /* textual values of query parameters */
     237             : 
     238             :     /* for storing result tuples */
     239             :     PGresult   *result;         /* result for query */
     240             :     int         num_tuples;     /* # of result tuples */
     241             :     int         next_tuple;     /* index of next one to return */
     242             :     Relation    resultRel;      /* relcache entry for the target relation */
     243             :     AttrNumber *attnoMap;       /* array of attnums of input user columns */
     244             :     AttrNumber  ctidAttno;      /* attnum of input ctid column */
     245             :     AttrNumber  oidAttno;       /* attnum of input oid column */
     246             :     bool        hasSystemCols;  /* are there system columns of resultRel? */
     247             : 
     248             :     /* working memory context */
     249             :     MemoryContext temp_cxt;     /* context for per-tuple temporary data */
     250             : } PgFdwDirectModifyState;
     251             : 
     252             : /*
     253             :  * Workspace for analyzing a foreign table.
     254             :  */
     255             : typedef struct PgFdwAnalyzeState
     256             : {
     257             :     Relation    rel;            /* relcache entry for the foreign table */
     258             :     AttInMetadata *attinmeta;   /* attribute datatype conversion metadata */
     259             :     List       *retrieved_attrs;    /* attr numbers retrieved by query */
     260             : 
     261             :     /* collected sample rows */
     262             :     HeapTuple  *rows;           /* array of size targrows */
     263             :     int         targrows;       /* target # of sample rows */
     264             :     int         numrows;        /* # of sample rows collected */
     265             : 
     266             :     /* for random sampling */
     267             :     double      samplerows;     /* # of rows fetched */
     268             :     double      rowstoskip;     /* # of rows to skip before next sample */
     269             :     ReservoirStateData rstate;  /* state for reservoir sampling */
     270             : 
     271             :     /* working memory contexts */
     272             :     MemoryContext anl_cxt;      /* context for per-analyze lifespan data */
     273             :     MemoryContext temp_cxt;     /* context for per-tuple temporary data */
     274             : } PgFdwAnalyzeState;
     275             : 
     276             : /*
     277             :  * This enum describes what's kept in the fdw_private list for a ForeignPath.
     278             :  * We store:
     279             :  *
     280             :  * 1) Boolean flag showing if the remote query has the final sort
     281             :  * 2) Boolean flag showing if the remote query has the LIMIT clause
     282             :  */
     283             : enum FdwPathPrivateIndex
     284             : {
     285             :     /* has-final-sort flag (as a Boolean node) */
     286             :     FdwPathPrivateHasFinalSort,
     287             :     /* has-limit flag (as a Boolean node) */
     288             :     FdwPathPrivateHasLimit,
     289             : };
     290             : 
     291             : /* Struct for extra information passed to estimate_path_cost_size() */
     292             : typedef struct
     293             : {
     294             :     PathTarget *target;
     295             :     bool        has_final_sort;
     296             :     bool        has_limit;
     297             :     double      limit_tuples;
     298             :     int64       count_est;
     299             :     int64       offset_est;
     300             : } PgFdwPathExtraData;
     301             : 
     302             : /*
     303             :  * Identify the attribute where data conversion fails.
     304             :  */
     305             : typedef struct ConversionLocation
     306             : {
     307             :     AttrNumber  cur_attno;      /* attribute number being processed, or 0 */
     308             :     Relation    rel;            /* foreign table being processed, or NULL */
     309             :     ForeignScanState *fsstate;  /* plan node being processed, or NULL */
     310             : } ConversionLocation;
     311             : 
     312             : /* Callback argument for ec_member_matches_foreign */
     313             : typedef struct
     314             : {
     315             :     Expr       *current;        /* current expr, or NULL if not yet found */
     316             :     List       *already_used;   /* expressions already dealt with */
     317             : } ec_member_foreign_arg;
     318             : 
     319             : /*
     320             :  * SQL functions
     321             :  */
     322          10 : PG_FUNCTION_INFO_V1(postgres_fdw_handler);
     323             : 
     324             : /*
     325             :  * FDW callback routines
     326             :  */
     327             : static void postgresGetForeignRelSize(PlannerInfo *root,
     328             :                                       RelOptInfo *baserel,
     329             :                                       Oid foreigntableid);
     330             : static void postgresGetForeignPaths(PlannerInfo *root,
     331             :                                     RelOptInfo *baserel,
     332             :                                     Oid foreigntableid);
     333             : static ForeignScan *postgresGetForeignPlan(PlannerInfo *root,
     334             :                                            RelOptInfo *foreignrel,
     335             :                                            Oid foreigntableid,
     336             :                                            ForeignPath *best_path,
     337             :                                            List *tlist,
     338             :                                            List *scan_clauses,
     339             :                                            Plan *outer_plan);
     340             : static void postgresBeginForeignScan(ForeignScanState *node, int eflags);
     341             : static TupleTableSlot *postgresIterateForeignScan(ForeignScanState *node);
     342             : static void postgresReScanForeignScan(ForeignScanState *node);
     343             : static void postgresEndForeignScan(ForeignScanState *node);
     344             : static void postgresAddForeignUpdateTargets(PlannerInfo *root,
     345             :                                             Index rtindex,
     346             :                                             RangeTblEntry *target_rte,
     347             :                                             Relation target_relation);
     348             : static List *postgresPlanForeignModify(PlannerInfo *root,
     349             :                                        ModifyTable *plan,
     350             :                                        Index resultRelation,
     351             :                                        int subplan_index);
     352             : static void postgresBeginForeignModify(ModifyTableState *mtstate,
     353             :                                        ResultRelInfo *resultRelInfo,
     354             :                                        List *fdw_private,
     355             :                                        int subplan_index,
     356             :                                        int eflags);
     357             : static TupleTableSlot *postgresExecForeignInsert(EState *estate,
     358             :                                                  ResultRelInfo *resultRelInfo,
     359             :                                                  TupleTableSlot *slot,
     360             :                                                  TupleTableSlot *planSlot);
     361             : static TupleTableSlot **postgresExecForeignBatchInsert(EState *estate,
     362             :                                                        ResultRelInfo *resultRelInfo,
     363             :                                                        TupleTableSlot **slots,
     364             :                                                        TupleTableSlot **planSlots,
     365             :                                                        int *numSlots);
     366             : static int  postgresGetForeignModifyBatchSize(ResultRelInfo *resultRelInfo);
     367             : static TupleTableSlot *postgresExecForeignUpdate(EState *estate,
     368             :                                                  ResultRelInfo *resultRelInfo,
     369             :                                                  TupleTableSlot *slot,
     370             :                                                  TupleTableSlot *planSlot);
     371             : static TupleTableSlot *postgresExecForeignDelete(EState *estate,
     372             :                                                  ResultRelInfo *resultRelInfo,
     373             :                                                  TupleTableSlot *slot,
     374             :                                                  TupleTableSlot *planSlot);
     375             : static void postgresEndForeignModify(EState *estate,
     376             :                                      ResultRelInfo *resultRelInfo);
     377             : static void postgresBeginForeignInsert(ModifyTableState *mtstate,
     378             :                                        ResultRelInfo *resultRelInfo);
     379             : static void postgresEndForeignInsert(EState *estate,
     380             :                                      ResultRelInfo *resultRelInfo);
     381             : static int  postgresIsForeignRelUpdatable(Relation rel);
     382             : static bool postgresPlanDirectModify(PlannerInfo *root,
     383             :                                      ModifyTable *plan,
     384             :                                      Index resultRelation,
     385             :                                      int subplan_index);
     386             : static void postgresBeginDirectModify(ForeignScanState *node, int eflags);
     387             : static TupleTableSlot *postgresIterateDirectModify(ForeignScanState *node);
     388             : static void postgresEndDirectModify(ForeignScanState *node);
     389             : static void postgresExplainForeignScan(ForeignScanState *node,
     390             :                                        ExplainState *es);
     391             : static void postgresExplainForeignModify(ModifyTableState *mtstate,
     392             :                                          ResultRelInfo *rinfo,
     393             :                                          List *fdw_private,
     394             :                                          int subplan_index,
     395             :                                          ExplainState *es);
     396             : static void postgresExplainDirectModify(ForeignScanState *node,
     397             :                                         ExplainState *es);
     398             : static void postgresExecForeignTruncate(List *rels,
     399             :                                         DropBehavior behavior,
     400             :                                         bool restart_seqs);
     401             : static bool postgresAnalyzeForeignTable(Relation relation,
     402             :                                         AcquireSampleRowsFunc *func,
     403             :                                         BlockNumber *totalpages);
     404             : static List *postgresImportForeignSchema(ImportForeignSchemaStmt *stmt,
     405             :                                          Oid serverOid);
     406             : static void postgresGetForeignJoinPaths(PlannerInfo *root,
     407             :                                         RelOptInfo *joinrel,
     408             :                                         RelOptInfo *outerrel,
     409             :                                         RelOptInfo *innerrel,
     410             :                                         JoinType jointype,
     411             :                                         JoinPathExtraData *extra);
     412             : static bool postgresRecheckForeignScan(ForeignScanState *node,
     413             :                                        TupleTableSlot *slot);
     414             : static void postgresGetForeignUpperPaths(PlannerInfo *root,
     415             :                                          UpperRelationKind stage,
     416             :                                          RelOptInfo *input_rel,
     417             :                                          RelOptInfo *output_rel,
     418             :                                          void *extra);
     419             : static bool postgresIsForeignPathAsyncCapable(ForeignPath *path);
     420             : static void postgresForeignAsyncRequest(AsyncRequest *areq);
     421             : static void postgresForeignAsyncConfigureWait(AsyncRequest *areq);
     422             : static void postgresForeignAsyncNotify(AsyncRequest *areq);
     423             : 
     424             : /*
     425             :  * Helper functions
     426             :  */
     427             : static void estimate_path_cost_size(PlannerInfo *root,
     428             :                                     RelOptInfo *foreignrel,
     429             :                                     List *param_join_conds,
     430             :                                     List *pathkeys,
     431             :                                     PgFdwPathExtraData *fpextra,
     432             :                                     double *p_rows, int *p_width,
     433             :                                     Cost *p_startup_cost, Cost *p_total_cost);
     434             : static void get_remote_estimate(const char *sql,
     435             :                                 PGconn *conn,
     436             :                                 double *rows,
     437             :                                 int *width,
     438             :                                 Cost *startup_cost,
     439             :                                 Cost *total_cost);
     440             : static void adjust_foreign_grouping_path_cost(PlannerInfo *root,
     441             :                                               List *pathkeys,
     442             :                                               double retrieved_rows,
     443             :                                               double width,
     444             :                                               double limit_tuples,
     445             :                                               Cost *p_startup_cost,
     446             :                                               Cost *p_run_cost);
     447             : static bool ec_member_matches_foreign(PlannerInfo *root, RelOptInfo *rel,
     448             :                                       EquivalenceClass *ec, EquivalenceMember *em,
     449             :                                       void *arg);
     450             : static void create_cursor(ForeignScanState *node);
     451             : static void fetch_more_data(ForeignScanState *node);
     452             : static void close_cursor(PGconn *conn, unsigned int cursor_number,
     453             :                          PgFdwConnState *conn_state);
     454             : static PgFdwModifyState *create_foreign_modify(EState *estate,
     455             :                                                RangeTblEntry *rte,
     456             :                                                ResultRelInfo *resultRelInfo,
     457             :                                                CmdType operation,
     458             :                                                Plan *subplan,
     459             :                                                char *query,
     460             :                                                List *target_attrs,
     461             :                                                int values_end,
     462             :                                                bool has_returning,
     463             :                                                List *retrieved_attrs);
     464             : static TupleTableSlot **execute_foreign_modify(EState *estate,
     465             :                                                ResultRelInfo *resultRelInfo,
     466             :                                                CmdType operation,
     467             :                                                TupleTableSlot **slots,
     468             :                                                TupleTableSlot **planSlots,
     469             :                                                int *numSlots);
     470             : static void prepare_foreign_modify(PgFdwModifyState *fmstate);
     471             : static const char **convert_prep_stmt_params(PgFdwModifyState *fmstate,
     472             :                                              ItemPointer tupleid,
     473             :                                              TupleTableSlot **slots,
     474             :                                              int numSlots);
     475             : static void store_returning_result(PgFdwModifyState *fmstate,
     476             :                                    TupleTableSlot *slot, PGresult *res);
     477             : static void finish_foreign_modify(PgFdwModifyState *fmstate);
     478             : static void deallocate_query(PgFdwModifyState *fmstate);
     479             : static List *build_remote_returning(Index rtindex, Relation rel,
     480             :                                     List *returningList);
     481             : static void rebuild_fdw_scan_tlist(ForeignScan *fscan, List *tlist);
     482             : static void execute_dml_stmt(ForeignScanState *node);
     483             : static TupleTableSlot *get_returning_data(ForeignScanState *node);
     484             : static void init_returning_filter(PgFdwDirectModifyState *dmstate,
     485             :                                   List *fdw_scan_tlist,
     486             :                                   Index rtindex);
     487             : static TupleTableSlot *apply_returning_filter(PgFdwDirectModifyState *dmstate,
     488             :                                               ResultRelInfo *resultRelInfo,
     489             :                                               TupleTableSlot *slot,
     490             :                                               EState *estate);
     491             : static void prepare_query_params(PlanState *node,
     492             :                                  List *fdw_exprs,
     493             :                                  int numParams,
     494             :                                  FmgrInfo **param_flinfo,
     495             :                                  List **param_exprs,
     496             :                                  const char ***param_values);
     497             : static void process_query_params(ExprContext *econtext,
     498             :                                  FmgrInfo *param_flinfo,
     499             :                                  List *param_exprs,
     500             :                                  const char **param_values);
     501             : static int  postgresAcquireSampleRowsFunc(Relation relation, int elevel,
     502             :                                           HeapTuple *rows, int targrows,
     503             :                                           double *totalrows,
     504             :                                           double *totaldeadrows);
     505             : static void analyze_row_processor(PGresult *res, int row,
     506             :                                   PgFdwAnalyzeState *astate);
     507             : static void produce_tuple_asynchronously(AsyncRequest *areq, bool fetch);
     508             : static void fetch_more_data_begin(AsyncRequest *areq);
     509             : static void complete_pending_request(AsyncRequest *areq);
     510             : static HeapTuple make_tuple_from_result_row(PGresult *res,
     511             :                                             int row,
     512             :                                             Relation rel,
     513             :                                             AttInMetadata *attinmeta,
     514             :                                             List *retrieved_attrs,
     515             :                                             ForeignScanState *fsstate,
     516             :                                             MemoryContext temp_context);
     517             : static void conversion_error_callback(void *arg);
     518             : static bool foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel,
     519             :                             JoinType jointype, RelOptInfo *outerrel, RelOptInfo *innerrel,
     520             :                             JoinPathExtraData *extra);
     521             : static bool foreign_grouping_ok(PlannerInfo *root, RelOptInfo *grouped_rel,
     522             :                                 Node *havingQual);
     523             : static List *get_useful_pathkeys_for_relation(PlannerInfo *root,
     524             :                                               RelOptInfo *rel);
     525             : static List *get_useful_ecs_for_relation(PlannerInfo *root, RelOptInfo *rel);
     526             : static void add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel,
     527             :                                             Path *epq_path, List *restrictlist);
     528             : static void add_foreign_grouping_paths(PlannerInfo *root,
     529             :                                        RelOptInfo *input_rel,
     530             :                                        RelOptInfo *grouped_rel,
     531             :                                        GroupPathExtraData *extra);
     532             : static void add_foreign_ordered_paths(PlannerInfo *root,
     533             :                                       RelOptInfo *input_rel,
     534             :                                       RelOptInfo *ordered_rel);
     535             : static void add_foreign_final_paths(PlannerInfo *root,
     536             :                                     RelOptInfo *input_rel,
     537             :                                     RelOptInfo *final_rel,
     538             :                                     FinalPathExtraData *extra);
     539             : static void apply_server_options(PgFdwRelationInfo *fpinfo);
     540             : static void apply_table_options(PgFdwRelationInfo *fpinfo);
     541             : static void merge_fdw_options(PgFdwRelationInfo *fpinfo,
     542             :                               const PgFdwRelationInfo *fpinfo_o,
     543             :                               const PgFdwRelationInfo *fpinfo_i);
     544             : static int  get_batch_size_option(Relation rel);
     545             : 
     546             : 
     547             : /*
     548             :  * Foreign-data wrapper handler function: return a struct with pointers
     549             :  * to my callback routines.
     550             :  */
     551             : Datum
     552        1280 : postgres_fdw_handler(PG_FUNCTION_ARGS)
     553             : {
     554        1280 :     FdwRoutine *routine = makeNode(FdwRoutine);
     555             : 
     556             :     /* Functions for scanning foreign tables */
     557        1280 :     routine->GetForeignRelSize = postgresGetForeignRelSize;
     558        1280 :     routine->GetForeignPaths = postgresGetForeignPaths;
     559        1280 :     routine->GetForeignPlan = postgresGetForeignPlan;
     560        1280 :     routine->BeginForeignScan = postgresBeginForeignScan;
     561        1280 :     routine->IterateForeignScan = postgresIterateForeignScan;
     562        1280 :     routine->ReScanForeignScan = postgresReScanForeignScan;
     563        1280 :     routine->EndForeignScan = postgresEndForeignScan;
     564             : 
     565             :     /* Functions for updating foreign tables */
     566        1280 :     routine->AddForeignUpdateTargets = postgresAddForeignUpdateTargets;
     567        1280 :     routine->PlanForeignModify = postgresPlanForeignModify;
     568        1280 :     routine->BeginForeignModify = postgresBeginForeignModify;
     569        1280 :     routine->ExecForeignInsert = postgresExecForeignInsert;
     570        1280 :     routine->ExecForeignBatchInsert = postgresExecForeignBatchInsert;
     571        1280 :     routine->GetForeignModifyBatchSize = postgresGetForeignModifyBatchSize;
     572        1280 :     routine->ExecForeignUpdate = postgresExecForeignUpdate;
     573        1280 :     routine->ExecForeignDelete = postgresExecForeignDelete;
     574        1280 :     routine->EndForeignModify = postgresEndForeignModify;
     575        1280 :     routine->BeginForeignInsert = postgresBeginForeignInsert;
     576        1280 :     routine->EndForeignInsert = postgresEndForeignInsert;
     577        1280 :     routine->IsForeignRelUpdatable = postgresIsForeignRelUpdatable;
     578        1280 :     routine->PlanDirectModify = postgresPlanDirectModify;
     579        1280 :     routine->BeginDirectModify = postgresBeginDirectModify;
     580        1280 :     routine->IterateDirectModify = postgresIterateDirectModify;
     581        1280 :     routine->EndDirectModify = postgresEndDirectModify;
     582             : 
     583             :     /* Function for EvalPlanQual rechecks */
     584        1280 :     routine->RecheckForeignScan = postgresRecheckForeignScan;
     585             :     /* Support functions for EXPLAIN */
     586        1280 :     routine->ExplainForeignScan = postgresExplainForeignScan;
     587        1280 :     routine->ExplainForeignModify = postgresExplainForeignModify;
     588        1280 :     routine->ExplainDirectModify = postgresExplainDirectModify;
     589             : 
     590             :     /* Support function for TRUNCATE */
     591        1280 :     routine->ExecForeignTruncate = postgresExecForeignTruncate;
     592             : 
     593             :     /* Support functions for ANALYZE */
     594        1280 :     routine->AnalyzeForeignTable = postgresAnalyzeForeignTable;
     595             : 
     596             :     /* Support functions for IMPORT FOREIGN SCHEMA */
     597        1280 :     routine->ImportForeignSchema = postgresImportForeignSchema;
     598             : 
     599             :     /* Support functions for join push-down */
     600        1280 :     routine->GetForeignJoinPaths = postgresGetForeignJoinPaths;
     601             : 
     602             :     /* Support functions for upper relation push-down */
     603        1280 :     routine->GetForeignUpperPaths = postgresGetForeignUpperPaths;
     604             : 
     605             :     /* Support functions for asynchronous execution */
     606        1280 :     routine->IsForeignPathAsyncCapable = postgresIsForeignPathAsyncCapable;
     607        1280 :     routine->ForeignAsyncRequest = postgresForeignAsyncRequest;
     608        1280 :     routine->ForeignAsyncConfigureWait = postgresForeignAsyncConfigureWait;
     609        1280 :     routine->ForeignAsyncNotify = postgresForeignAsyncNotify;
     610             : 
     611        1280 :     PG_RETURN_POINTER(routine);
     612             : }
     613             : 
     614             : /*
     615             :  * postgresGetForeignRelSize
     616             :  *      Estimate # of rows and width of the result of the scan
     617             :  *
     618             :  * We should consider the effect of all baserestrictinfo clauses here, but
     619             :  * not any join clauses.
     620             :  */
     621             : static void
     622        2276 : postgresGetForeignRelSize(PlannerInfo *root,
     623             :                           RelOptInfo *baserel,
     624             :                           Oid foreigntableid)
     625             : {
     626             :     PgFdwRelationInfo *fpinfo;
     627             :     ListCell   *lc;
     628             : 
     629             :     /*
     630             :      * We use PgFdwRelationInfo to pass various information to subsequent
     631             :      * functions.
     632             :      */
     633        2276 :     fpinfo = (PgFdwRelationInfo *) palloc0(sizeof(PgFdwRelationInfo));
     634        2276 :     baserel->fdw_private = (void *) fpinfo;
     635             : 
     636             :     /* Base foreign tables need to be pushed down always. */
     637        2276 :     fpinfo->pushdown_safe = true;
     638             : 
     639             :     /* Look up foreign-table catalog info. */
     640        2276 :     fpinfo->table = GetForeignTable(foreigntableid);
     641        2276 :     fpinfo->server = GetForeignServer(fpinfo->table->serverid);
     642             : 
     643             :     /*
     644             :      * Extract user-settable option values.  Note that per-table settings of
     645             :      * use_remote_estimate, fetch_size and async_capable override per-server
     646             :      * settings of them, respectively.
     647             :      */
     648        2276 :     fpinfo->use_remote_estimate = false;
     649        2276 :     fpinfo->fdw_startup_cost = DEFAULT_FDW_STARTUP_COST;
     650        2276 :     fpinfo->fdw_tuple_cost = DEFAULT_FDW_TUPLE_COST;
     651        2276 :     fpinfo->shippable_extensions = NIL;
     652        2276 :     fpinfo->fetch_size = 100;
     653        2276 :     fpinfo->async_capable = false;
     654             : 
     655        2276 :     apply_server_options(fpinfo);
     656        2276 :     apply_table_options(fpinfo);
     657             : 
     658             :     /*
     659             :      * If the table or the server is configured to use remote estimates,
     660             :      * identify which user to do remote access as during planning.  This
     661             :      * should match what ExecCheckPermissions() does.  If we fail due to lack
     662             :      * of permissions, the query would have failed at runtime anyway.
     663             :      */
     664        2276 :     if (fpinfo->use_remote_estimate)
     665             :     {
     666             :         Oid         userid;
     667             : 
     668         588 :         userid = OidIsValid(baserel->userid) ? baserel->userid : GetUserId();
     669         588 :         fpinfo->user = GetUserMapping(userid, fpinfo->server->serverid);
     670             :     }
     671             :     else
     672        1688 :         fpinfo->user = NULL;
     673             : 
     674             :     /*
     675             :      * Identify which baserestrictinfo clauses can be sent to the remote
     676             :      * server and which can't.
     677             :      */
     678        2272 :     classifyConditions(root, baserel, baserel->baserestrictinfo,
     679             :                        &fpinfo->remote_conds, &fpinfo->local_conds);
     680             : 
     681             :     /*
     682             :      * Identify which attributes will need to be retrieved from the remote
     683             :      * server.  These include all attrs needed for joins or final output, plus
     684             :      * all attrs used in the local_conds.  (Note: if we end up using a
     685             :      * parameterized scan, it's possible that some of the join clauses will be
     686             :      * sent to the remote and thus we wouldn't really need to retrieve the
     687             :      * columns used in them.  Doesn't seem worth detecting that case though.)
     688             :      */
     689        2272 :     fpinfo->attrs_used = NULL;
     690        2272 :     pull_varattnos((Node *) baserel->reltarget->exprs, baserel->relid,
     691             :                    &fpinfo->attrs_used);
     692        2422 :     foreach(lc, fpinfo->local_conds)
     693             :     {
     694         150 :         RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
     695             : 
     696         150 :         pull_varattnos((Node *) rinfo->clause, baserel->relid,
     697             :                        &fpinfo->attrs_used);
     698             :     }
     699             : 
     700             :     /*
     701             :      * Compute the selectivity and cost of the local_conds, so we don't have
     702             :      * to do it over again for each path.  The best we can do for these
     703             :      * conditions is to estimate selectivity on the basis of local statistics.
     704             :      */
     705        4544 :     fpinfo->local_conds_sel = clauselist_selectivity(root,
     706             :                                                      fpinfo->local_conds,
     707        2272 :                                                      baserel->relid,
     708             :                                                      JOIN_INNER,
     709             :                                                      NULL);
     710             : 
     711        2272 :     cost_qual_eval(&fpinfo->local_conds_cost, fpinfo->local_conds, root);
     712             : 
     713             :     /*
     714             :      * Set # of retrieved rows and cached relation costs to some negative
     715             :      * value, so that we can detect when they are set to some sensible values,
     716             :      * during one (usually the first) of the calls to estimate_path_cost_size.
     717             :      */
     718        2272 :     fpinfo->retrieved_rows = -1;
     719        2272 :     fpinfo->rel_startup_cost = -1;
     720        2272 :     fpinfo->rel_total_cost = -1;
     721             : 
     722             :     /*
     723             :      * If the table or the server is configured to use remote estimates,
     724             :      * connect to the foreign server and execute EXPLAIN to estimate the
     725             :      * number of rows selected by the restriction clauses, as well as the
     726             :      * average row width.  Otherwise, estimate using whatever statistics we
     727             :      * have locally, in a way similar to ordinary tables.
     728             :      */
     729        2272 :     if (fpinfo->use_remote_estimate)
     730             :     {
     731             :         /*
     732             :          * Get cost/size estimates with help of remote server.  Save the
     733             :          * values in fpinfo so we don't need to do it again to generate the
     734             :          * basic foreign path.
     735             :          */
     736         584 :         estimate_path_cost_size(root, baserel, NIL, NIL, NULL,
     737             :                                 &fpinfo->rows, &fpinfo->width,
     738             :                                 &fpinfo->startup_cost, &fpinfo->total_cost);
     739             : 
     740             :         /* Report estimated baserel size to planner. */
     741         584 :         baserel->rows = fpinfo->rows;
     742         584 :         baserel->reltarget->width = fpinfo->width;
     743             :     }
     744             :     else
     745             :     {
     746             :         /*
     747             :          * If the foreign table has never been ANALYZEd, it will have
     748             :          * reltuples < 0, meaning "unknown".  We can't do much if we're not
     749             :          * allowed to consult the remote server, but we can use a hack similar
     750             :          * to plancat.c's treatment of empty relations: use a minimum size
     751             :          * estimate of 10 pages, and divide by the column-datatype-based width
     752             :          * estimate to get the corresponding number of tuples.
     753             :          */
     754        1688 :         if (baserel->tuples < 0)
     755             :         {
     756         540 :             baserel->pages = 10;
     757         540 :             baserel->tuples =
     758         540 :                 (10 * BLCKSZ) / (baserel->reltarget->width +
     759             :                                  MAXALIGN(SizeofHeapTupleHeader));
     760             :         }
     761             : 
     762             :         /* Estimate baserel size as best we can with local statistics. */
     763        1688 :         set_baserel_size_estimates(root, baserel);
     764             : 
     765             :         /* Fill in basically-bogus cost estimates for use later. */
     766        1688 :         estimate_path_cost_size(root, baserel, NIL, NIL, NULL,
     767             :                                 &fpinfo->rows, &fpinfo->width,
     768             :                                 &fpinfo->startup_cost, &fpinfo->total_cost);
     769             :     }
     770             : 
     771             :     /*
     772             :      * fpinfo->relation_name gets the numeric rangetable index of the foreign
     773             :      * table RTE.  (If this query gets EXPLAIN'd, we'll convert that to a
     774             :      * human-readable string at that time.)
     775             :      */
     776        2272 :     fpinfo->relation_name = psprintf("%u", baserel->relid);
     777             : 
     778             :     /* No outer and inner relations. */
     779        2272 :     fpinfo->make_outerrel_subquery = false;
     780        2272 :     fpinfo->make_innerrel_subquery = false;
     781        2272 :     fpinfo->lower_subquery_rels = NULL;
     782        2272 :     fpinfo->hidden_subquery_rels = NULL;
     783             :     /* Set the relation index. */
     784        2272 :     fpinfo->relation_index = baserel->relid;
     785        2272 : }
     786             : 
     787             : /*
     788             :  * get_useful_ecs_for_relation
     789             :  *      Determine which EquivalenceClasses might be involved in useful
     790             :  *      orderings of this relation.
     791             :  *
     792             :  * This function is in some respects a mirror image of the core function
     793             :  * pathkeys_useful_for_merging: for a regular table, we know what indexes
     794             :  * we have and want to test whether any of them are useful.  For a foreign
     795             :  * table, we don't know what indexes are present on the remote side but
     796             :  * want to speculate about which ones we'd like to use if they existed.
     797             :  *
     798             :  * This function returns a list of potentially-useful equivalence classes,
     799             :  * but it does not guarantee that an EquivalenceMember exists which contains
     800             :  * Vars only from the given relation.  For example, given ft1 JOIN t1 ON
     801             :  * ft1.x + t1.x = 0, this function will say that the equivalence class
     802             :  * containing ft1.x + t1.x is potentially useful.  Supposing ft1 is remote and
     803             :  * t1 is local (or on a different server), it will turn out that no useful
     804             :  * ORDER BY clause can be generated.  It's not our job to figure that out
     805             :  * here; we're only interested in identifying relevant ECs.
     806             :  */
     807             : static List *
     808        1026 : get_useful_ecs_for_relation(PlannerInfo *root, RelOptInfo *rel)
     809             : {
     810        1026 :     List       *useful_eclass_list = NIL;
     811             :     ListCell   *lc;
     812             :     Relids      relids;
     813             : 
     814             :     /*
     815             :      * First, consider whether any active EC is potentially useful for a merge
     816             :      * join against this relation.
     817             :      */
     818        1026 :     if (rel->has_eclass_joins)
     819             :     {
     820        1268 :         foreach(lc, root->eq_classes)
     821             :         {
     822         878 :             EquivalenceClass *cur_ec = (EquivalenceClass *) lfirst(lc);
     823             : 
     824         878 :             if (eclass_useful_for_merging(root, cur_ec, rel))
     825         482 :                 useful_eclass_list = lappend(useful_eclass_list, cur_ec);
     826             :         }
     827             :     }
     828             : 
     829             :     /*
     830             :      * Next, consider whether there are any non-EC derivable join clauses that
     831             :      * are merge-joinable.  If the joininfo list is empty, we can exit
     832             :      * quickly.
     833             :      */
     834        1026 :     if (rel->joininfo == NIL)
     835         758 :         return useful_eclass_list;
     836             : 
     837             :     /* If this is a child rel, we must use the topmost parent rel to search. */
     838         268 :     if (IS_OTHER_REL(rel))
     839             :     {
     840             :         Assert(!bms_is_empty(rel->top_parent_relids));
     841          40 :         relids = rel->top_parent_relids;
     842             :     }
     843             :     else
     844         228 :         relids = rel->relids;
     845             : 
     846             :     /* Check each join clause in turn. */
     847         658 :     foreach(lc, rel->joininfo)
     848             :     {
     849         390 :         RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(lc);
     850             : 
     851             :         /* Consider only mergejoinable clauses */
     852         390 :         if (restrictinfo->mergeopfamilies == NIL)
     853          28 :             continue;
     854             : 
     855             :         /* Make sure we've got canonical ECs. */
     856         362 :         update_mergeclause_eclasses(root, restrictinfo);
     857             : 
     858             :         /*
     859             :          * restrictinfo->mergeopfamilies != NIL is sufficient to guarantee
     860             :          * that left_ec and right_ec will be initialized, per comments in
     861             :          * distribute_qual_to_rels.
     862             :          *
     863             :          * We want to identify which side of this merge-joinable clause
     864             :          * contains columns from the relation produced by this RelOptInfo. We
     865             :          * test for overlap, not containment, because there could be extra
     866             :          * relations on either side.  For example, suppose we've got something
     867             :          * like ((A JOIN B ON A.x = B.x) JOIN C ON A.y = C.y) LEFT JOIN D ON
     868             :          * A.y = D.y.  The input rel might be the joinrel between A and B, and
     869             :          * we'll consider the join clause A.y = D.y. relids contains a
     870             :          * relation not involved in the join class (B) and the equivalence
     871             :          * class for the left-hand side of the clause contains a relation not
     872             :          * involved in the input rel (C).  Despite the fact that we have only
     873             :          * overlap and not containment in either direction, A.y is potentially
     874             :          * useful as a sort column.
     875             :          *
     876             :          * Note that it's even possible that relids overlaps neither side of
     877             :          * the join clause.  For example, consider A LEFT JOIN B ON A.x = B.x
     878             :          * AND A.x = 1.  The clause A.x = 1 will appear in B's joininfo list,
     879             :          * but overlaps neither side of B.  In that case, we just skip this
     880             :          * join clause, since it doesn't suggest a useful sort order for this
     881             :          * relation.
     882             :          */
     883         362 :         if (bms_overlap(relids, restrictinfo->right_ec->ec_relids))
     884         164 :             useful_eclass_list = list_append_unique_ptr(useful_eclass_list,
     885         164 :                                                         restrictinfo->right_ec);
     886         198 :         else if (bms_overlap(relids, restrictinfo->left_ec->ec_relids))
     887         180 :             useful_eclass_list = list_append_unique_ptr(useful_eclass_list,
     888         180 :                                                         restrictinfo->left_ec);
     889             :     }
     890             : 
     891         268 :     return useful_eclass_list;
     892             : }
     893             : 
     894             : /*
     895             :  * get_useful_pathkeys_for_relation
     896             :  *      Determine which orderings of a relation might be useful.
     897             :  *
     898             :  * Getting data in sorted order can be useful either because the requested
     899             :  * order matches the final output ordering for the overall query we're
     900             :  * planning, or because it enables an efficient merge join.  Here, we try
     901             :  * to figure out which pathkeys to consider.
     902             :  */
     903             : static List *
     904        2890 : get_useful_pathkeys_for_relation(PlannerInfo *root, RelOptInfo *rel)
     905             : {
     906        2890 :     List       *useful_pathkeys_list = NIL;
     907             :     List       *useful_eclass_list;
     908        2890 :     PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) rel->fdw_private;
     909        2890 :     EquivalenceClass *query_ec = NULL;
     910             :     ListCell   *lc;
     911             : 
     912             :     /*
     913             :      * Pushing the query_pathkeys to the remote server is always worth
     914             :      * considering, because it might let us avoid a local sort.
     915             :      */
     916        2890 :     fpinfo->qp_is_pushdown_safe = false;
     917        2890 :     if (root->query_pathkeys)
     918             :     {
     919        1180 :         bool        query_pathkeys_ok = true;
     920             : 
     921        2248 :         foreach(lc, root->query_pathkeys)
     922             :         {
     923        1518 :             PathKey    *pathkey = (PathKey *) lfirst(lc);
     924             : 
     925             :             /*
     926             :              * The planner and executor don't have any clever strategy for
     927             :              * taking data sorted by a prefix of the query's pathkeys and
     928             :              * getting it to be sorted by all of those pathkeys. We'll just
     929             :              * end up resorting the entire data set.  So, unless we can push
     930             :              * down all of the query pathkeys, forget it.
     931             :              */
     932        1518 :             if (!is_foreign_pathkey(root, rel, pathkey))
     933             :             {
     934         450 :                 query_pathkeys_ok = false;
     935         450 :                 break;
     936             :             }
     937             :         }
     938             : 
     939        1180 :         if (query_pathkeys_ok)
     940             :         {
     941         730 :             useful_pathkeys_list = list_make1(list_copy(root->query_pathkeys));
     942         730 :             fpinfo->qp_is_pushdown_safe = true;
     943             :         }
     944             :     }
     945             : 
     946             :     /*
     947             :      * Even if we're not using remote estimates, having the remote side do the
     948             :      * sort generally won't be any worse than doing it locally, and it might
     949             :      * be much better if the remote side can generate data in the right order
     950             :      * without needing a sort at all.  However, what we're going to do next is
     951             :      * try to generate pathkeys that seem promising for possible merge joins,
     952             :      * and that's more speculative.  A wrong choice might hurt quite a bit, so
     953             :      * bail out if we can't use remote estimates.
     954             :      */
     955        2890 :     if (!fpinfo->use_remote_estimate)
     956        1864 :         return useful_pathkeys_list;
     957             : 
     958             :     /* Get the list of interesting EquivalenceClasses. */
     959        1026 :     useful_eclass_list = get_useful_ecs_for_relation(root, rel);
     960             : 
     961             :     /* Extract unique EC for query, if any, so we don't consider it again. */
     962        1026 :     if (list_length(root->query_pathkeys) == 1)
     963             :     {
     964         330 :         PathKey    *query_pathkey = linitial(root->query_pathkeys);
     965             : 
     966         330 :         query_ec = query_pathkey->pk_eclass;
     967             :     }
     968             : 
     969             :     /*
     970             :      * As a heuristic, the only pathkeys we consider here are those of length
     971             :      * one.  It's surely possible to consider more, but since each one we
     972             :      * choose to consider will generate a round-trip to the remote side, we
     973             :      * need to be a bit cautious here.  It would sure be nice to have a local
     974             :      * cache of information about remote index definitions...
     975             :      */
     976        1806 :     foreach(lc, useful_eclass_list)
     977             :     {
     978         780 :         EquivalenceClass *cur_ec = lfirst(lc);
     979             :         PathKey    *pathkey;
     980             : 
     981             :         /* If redundant with what we did above, skip it. */
     982         780 :         if (cur_ec == query_ec)
     983         174 :             continue;
     984             : 
     985             :         /* Can't push down the sort if the EC's opfamily is not shippable. */
     986         718 :         if (!is_shippable(linitial_oid(cur_ec->ec_opfamilies),
     987             :                           OperatorFamilyRelationId, fpinfo))
     988           0 :             continue;
     989             : 
     990             :         /* If no pushable expression for this rel, skip it. */
     991         718 :         if (find_em_for_rel(root, cur_ec, rel) == NULL)
     992         112 :             continue;
     993             : 
     994             :         /* Looks like we can generate a pathkey, so let's do it. */
     995         606 :         pathkey = make_canonical_pathkey(root, cur_ec,
     996         606 :                                          linitial_oid(cur_ec->ec_opfamilies),
     997             :                                          BTLessStrategyNumber,
     998             :                                          false);
     999         606 :         useful_pathkeys_list = lappend(useful_pathkeys_list,
    1000         606 :                                        list_make1(pathkey));
    1001             :     }
    1002             : 
    1003        1026 :     return useful_pathkeys_list;
    1004             : }
    1005             : 
    1006             : /*
    1007             :  * postgresGetForeignPaths
    1008             :  *      Create possible scan paths for a scan on the foreign table
    1009             :  */
    1010             : static void
    1011        2272 : postgresGetForeignPaths(PlannerInfo *root,
    1012             :                         RelOptInfo *baserel,
    1013             :                         Oid foreigntableid)
    1014             : {
    1015        2272 :     PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) baserel->fdw_private;
    1016             :     ForeignPath *path;
    1017             :     List       *ppi_list;
    1018             :     ListCell   *lc;
    1019             : 
    1020             :     /*
    1021             :      * Create simplest ForeignScan path node and add it to baserel.  This path
    1022             :      * corresponds to SeqScan path of regular tables (though depending on what
    1023             :      * baserestrict conditions we were able to send to remote, there might
    1024             :      * actually be an indexscan happening there).  We already did all the work
    1025             :      * to estimate cost and size of this path.
    1026             :      *
    1027             :      * Although this path uses no join clauses, it could still have required
    1028             :      * parameterization due to LATERAL refs in its tlist.
    1029             :      */
    1030        2272 :     path = create_foreignscan_path(root, baserel,
    1031             :                                    NULL,    /* default pathtarget */
    1032             :                                    fpinfo->rows,
    1033             :                                    fpinfo->startup_cost,
    1034             :                                    fpinfo->total_cost,
    1035             :                                    NIL, /* no pathkeys */
    1036             :                                    baserel->lateral_relids,
    1037             :                                    NULL,    /* no extra plan */
    1038             :                                    NIL, /* no fdw_restrictinfo list */
    1039             :                                    NIL);    /* no fdw_private list */
    1040        2272 :     add_path(baserel, (Path *) path);
    1041             : 
    1042             :     /* Add paths with pathkeys */
    1043        2272 :     add_paths_with_pathkeys_for_rel(root, baserel, NULL, NIL);
    1044             : 
    1045             :     /*
    1046             :      * If we're not using remote estimates, stop here.  We have no way to
    1047             :      * estimate whether any join clauses would be worth sending across, so
    1048             :      * don't bother building parameterized paths.
    1049             :      */
    1050        2272 :     if (!fpinfo->use_remote_estimate)
    1051        1688 :         return;
    1052             : 
    1053             :     /*
    1054             :      * Thumb through all join clauses for the rel to identify which outer
    1055             :      * relations could supply one or more safe-to-send-to-remote join clauses.
    1056             :      * We'll build a parameterized path for each such outer relation.
    1057             :      *
    1058             :      * It's convenient to manage this by representing each candidate outer
    1059             :      * relation by the ParamPathInfo node for it.  We can then use the
    1060             :      * ppi_clauses list in the ParamPathInfo node directly as a list of the
    1061             :      * interesting join clauses for that rel.  This takes care of the
    1062             :      * possibility that there are multiple safe join clauses for such a rel,
    1063             :      * and also ensures that we account for unsafe join clauses that we'll
    1064             :      * still have to enforce locally (since the parameterized-path machinery
    1065             :      * insists that we handle all movable clauses).
    1066             :      */
    1067         584 :     ppi_list = NIL;
    1068         858 :     foreach(lc, baserel->joininfo)
    1069             :     {
    1070         274 :         RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
    1071             :         Relids      required_outer;
    1072             :         ParamPathInfo *param_info;
    1073             : 
    1074             :         /* Check if clause can be moved to this rel */
    1075         274 :         if (!join_clause_is_movable_to(rinfo, baserel))
    1076         188 :             continue;
    1077             : 
    1078             :         /* See if it is safe to send to remote */
    1079          86 :         if (!is_foreign_expr(root, baserel, rinfo->clause))
    1080          14 :             continue;
    1081             : 
    1082             :         /* Calculate required outer rels for the resulting path */
    1083          72 :         required_outer = bms_union(rinfo->clause_relids,
    1084          72 :                                    baserel->lateral_relids);
    1085             :         /* We do not want the foreign rel itself listed in required_outer */
    1086          72 :         required_outer = bms_del_member(required_outer, baserel->relid);
    1087             : 
    1088             :         /*
    1089             :          * required_outer probably can't be empty here, but if it were, we
    1090             :          * couldn't make a parameterized path.
    1091             :          */
    1092          72 :         if (bms_is_empty(required_outer))
    1093           0 :             continue;
    1094             : 
    1095             :         /* Get the ParamPathInfo */
    1096          72 :         param_info = get_baserel_parampathinfo(root, baserel,
    1097             :                                                required_outer);
    1098             :         Assert(param_info != NULL);
    1099             : 
    1100             :         /*
    1101             :          * Add it to list unless we already have it.  Testing pointer equality
    1102             :          * is OK since get_baserel_parampathinfo won't make duplicates.
    1103             :          */
    1104          72 :         ppi_list = list_append_unique_ptr(ppi_list, param_info);
    1105             :     }
    1106             : 
    1107             :     /*
    1108             :      * The above scan examined only "generic" join clauses, not those that
    1109             :      * were absorbed into EquivalenceClauses.  See if we can make anything out
    1110             :      * of EquivalenceClauses.
    1111             :      */
    1112         584 :     if (baserel->has_eclass_joins)
    1113             :     {
    1114             :         /*
    1115             :          * We repeatedly scan the eclass list looking for column references
    1116             :          * (or expressions) belonging to the foreign rel.  Each time we find
    1117             :          * one, we generate a list of equivalence joinclauses for it, and then
    1118             :          * see if any are safe to send to the remote.  Repeat till there are
    1119             :          * no more candidate EC members.
    1120             :          */
    1121             :         ec_member_foreign_arg arg;
    1122             : 
    1123         254 :         arg.already_used = NIL;
    1124             :         for (;;)
    1125         278 :         {
    1126             :             List       *clauses;
    1127             : 
    1128             :             /* Make clauses, skipping any that join to lateral_referencers */
    1129         532 :             arg.current = NULL;
    1130         532 :             clauses = generate_implied_equalities_for_column(root,
    1131             :                                                              baserel,
    1132             :                                                              ec_member_matches_foreign,
    1133             :                                                              (void *) &arg,
    1134             :                                                              baserel->lateral_referencers);
    1135             : 
    1136             :             /* Done if there are no more expressions in the foreign rel */
    1137         532 :             if (arg.current == NULL)
    1138             :             {
    1139             :                 Assert(clauses == NIL);
    1140         254 :                 break;
    1141             :             }
    1142             : 
    1143             :             /* Scan the extracted join clauses */
    1144         608 :             foreach(lc, clauses)
    1145             :             {
    1146         330 :                 RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
    1147             :                 Relids      required_outer;
    1148             :                 ParamPathInfo *param_info;
    1149             : 
    1150             :                 /* Check if clause can be moved to this rel */
    1151         330 :                 if (!join_clause_is_movable_to(rinfo, baserel))
    1152           0 :                     continue;
    1153             : 
    1154             :                 /* See if it is safe to send to remote */
    1155         330 :                 if (!is_foreign_expr(root, baserel, rinfo->clause))
    1156          14 :                     continue;
    1157             : 
    1158             :                 /* Calculate required outer rels for the resulting path */
    1159         316 :                 required_outer = bms_union(rinfo->clause_relids,
    1160         316 :                                            baserel->lateral_relids);
    1161         316 :                 required_outer = bms_del_member(required_outer, baserel->relid);
    1162         316 :                 if (bms_is_empty(required_outer))
    1163           0 :                     continue;
    1164             : 
    1165             :                 /* Get the ParamPathInfo */
    1166         316 :                 param_info = get_baserel_parampathinfo(root, baserel,
    1167             :                                                        required_outer);
    1168             :                 Assert(param_info != NULL);
    1169             : 
    1170             :                 /* Add it to list unless we already have it */
    1171         316 :                 ppi_list = list_append_unique_ptr(ppi_list, param_info);
    1172             :             }
    1173             : 
    1174             :             /* Try again, now ignoring the expression we found this time */
    1175         278 :             arg.already_used = lappend(arg.already_used, arg.current);
    1176             :         }
    1177             :     }
    1178             : 
    1179             :     /*
    1180             :      * Now build a path for each useful outer relation.
    1181             :      */
    1182         952 :     foreach(lc, ppi_list)
    1183             :     {
    1184         368 :         ParamPathInfo *param_info = (ParamPathInfo *) lfirst(lc);
    1185             :         double      rows;
    1186             :         int         width;
    1187             :         Cost        startup_cost;
    1188             :         Cost        total_cost;
    1189             : 
    1190             :         /* Get a cost estimate from the remote */
    1191         368 :         estimate_path_cost_size(root, baserel,
    1192             :                                 param_info->ppi_clauses, NIL, NULL,
    1193             :                                 &rows, &width,
    1194             :                                 &startup_cost, &total_cost);
    1195             : 
    1196             :         /*
    1197             :          * ppi_rows currently won't get looked at by anything, but still we
    1198             :          * may as well ensure that it matches our idea of the rowcount.
    1199             :          */
    1200         368 :         param_info->ppi_rows = rows;
    1201             : 
    1202             :         /* Make the path */
    1203         368 :         path = create_foreignscan_path(root, baserel,
    1204             :                                        NULL,    /* default pathtarget */
    1205             :                                        rows,
    1206             :                                        startup_cost,
    1207             :                                        total_cost,
    1208             :                                        NIL, /* no pathkeys */
    1209             :                                        param_info->ppi_req_outer,
    1210             :                                        NULL,
    1211             :                                        NIL, /* no fdw_restrictinfo list */
    1212             :                                        NIL);    /* no fdw_private list */
    1213         368 :         add_path(baserel, (Path *) path);
    1214             :     }
    1215             : }
    1216             : 
    1217             : /*
    1218             :  * postgresGetForeignPlan
    1219             :  *      Create ForeignScan plan node which implements selected best path
    1220             :  */
    1221             : static ForeignScan *
    1222        1902 : postgresGetForeignPlan(PlannerInfo *root,
    1223             :                        RelOptInfo *foreignrel,
    1224             :                        Oid foreigntableid,
    1225             :                        ForeignPath *best_path,
    1226             :                        List *tlist,
    1227             :                        List *scan_clauses,
    1228             :                        Plan *outer_plan)
    1229             : {
    1230        1902 :     PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
    1231             :     Index       scan_relid;
    1232             :     List       *fdw_private;
    1233        1902 :     List       *remote_exprs = NIL;
    1234        1902 :     List       *local_exprs = NIL;
    1235        1902 :     List       *params_list = NIL;
    1236        1902 :     List       *fdw_scan_tlist = NIL;
    1237        1902 :     List       *fdw_recheck_quals = NIL;
    1238             :     List       *retrieved_attrs;
    1239             :     StringInfoData sql;
    1240        1902 :     bool        has_final_sort = false;
    1241        1902 :     bool        has_limit = false;
    1242             :     ListCell   *lc;
    1243             : 
    1244             :     /*
    1245             :      * Get FDW private data created by postgresGetForeignUpperPaths(), if any.
    1246             :      */
    1247        1902 :     if (best_path->fdw_private)
    1248             :     {
    1249         296 :         has_final_sort = boolVal(list_nth(best_path->fdw_private,
    1250             :                                           FdwPathPrivateHasFinalSort));
    1251         296 :         has_limit = boolVal(list_nth(best_path->fdw_private,
    1252             :                                      FdwPathPrivateHasLimit));
    1253             :     }
    1254             : 
    1255        1902 :     if (IS_SIMPLE_REL(foreignrel))
    1256             :     {
    1257             :         /*
    1258             :          * For base relations, set scan_relid as the relid of the relation.
    1259             :          */
    1260        1362 :         scan_relid = foreignrel->relid;
    1261             : 
    1262             :         /*
    1263             :          * In a base-relation scan, we must apply the given scan_clauses.
    1264             :          *
    1265             :          * Separate the scan_clauses into those that can be executed remotely
    1266             :          * and those that can't.  baserestrictinfo clauses that were
    1267             :          * previously determined to be safe or unsafe by classifyConditions
    1268             :          * are found in fpinfo->remote_conds and fpinfo->local_conds. Anything
    1269             :          * else in the scan_clauses list will be a join clause, which we have
    1270             :          * to check for remote-safety.
    1271             :          *
    1272             :          * Note: the join clauses we see here should be the exact same ones
    1273             :          * previously examined by postgresGetForeignPaths.  Possibly it'd be
    1274             :          * worth passing forward the classification work done then, rather
    1275             :          * than repeating it here.
    1276             :          *
    1277             :          * This code must match "extract_actual_clauses(scan_clauses, false)"
    1278             :          * except for the additional decision about remote versus local
    1279             :          * execution.
    1280             :          */
    1281        2044 :         foreach(lc, scan_clauses)
    1282             :         {
    1283         682 :             RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
    1284             : 
    1285             :             /* Ignore any pseudoconstants, they're dealt with elsewhere */
    1286         682 :             if (rinfo->pseudoconstant)
    1287           8 :                 continue;
    1288             : 
    1289         674 :             if (list_member_ptr(fpinfo->remote_conds, rinfo))
    1290         506 :                 remote_exprs = lappend(remote_exprs, rinfo->clause);
    1291         168 :             else if (list_member_ptr(fpinfo->local_conds, rinfo))
    1292         142 :                 local_exprs = lappend(local_exprs, rinfo->clause);
    1293          26 :             else if (is_foreign_expr(root, foreignrel, rinfo->clause))
    1294          22 :                 remote_exprs = lappend(remote_exprs, rinfo->clause);
    1295             :             else
    1296           4 :                 local_exprs = lappend(local_exprs, rinfo->clause);
    1297             :         }
    1298             : 
    1299             :         /*
    1300             :          * For a base-relation scan, we have to support EPQ recheck, which
    1301             :          * should recheck all the remote quals.
    1302             :          */
    1303        1362 :         fdw_recheck_quals = remote_exprs;
    1304             :     }
    1305             :     else
    1306             :     {
    1307             :         /*
    1308             :          * Join relation or upper relation - set scan_relid to 0.
    1309             :          */
    1310         540 :         scan_relid = 0;
    1311             : 
    1312             :         /*
    1313             :          * For a join rel, baserestrictinfo is NIL and we are not considering
    1314             :          * parameterization right now, so there should be no scan_clauses for
    1315             :          * a joinrel or an upper rel either.
    1316             :          */
    1317             :         Assert(!scan_clauses);
    1318             : 
    1319             :         /*
    1320             :          * Instead we get the conditions to apply from the fdw_private
    1321             :          * structure.
    1322             :          */
    1323         540 :         remote_exprs = extract_actual_clauses(fpinfo->remote_conds, false);
    1324         540 :         local_exprs = extract_actual_clauses(fpinfo->local_conds, false);
    1325             : 
    1326             :         /*
    1327             :          * We leave fdw_recheck_quals empty in this case, since we never need
    1328             :          * to apply EPQ recheck clauses.  In the case of a joinrel, EPQ
    1329             :          * recheck is handled elsewhere --- see postgresGetForeignJoinPaths().
    1330             :          * If we're planning an upperrel (ie, remote grouping or aggregation)
    1331             :          * then there's no EPQ to do because SELECT FOR UPDATE wouldn't be
    1332             :          * allowed, and indeed we *can't* put the remote clauses into
    1333             :          * fdw_recheck_quals because the unaggregated Vars won't be available
    1334             :          * locally.
    1335             :          */
    1336             : 
    1337             :         /* Build the list of columns to be fetched from the foreign server. */
    1338         540 :         fdw_scan_tlist = build_tlist_to_deparse(foreignrel);
    1339             : 
    1340             :         /*
    1341             :          * Ensure that the outer plan produces a tuple whose descriptor
    1342             :          * matches our scan tuple slot.  Also, remove the local conditions
    1343             :          * from outer plan's quals, lest they be evaluated twice, once by the
    1344             :          * local plan and once by the scan.
    1345             :          */
    1346         540 :         if (outer_plan)
    1347             :         {
    1348             :             /*
    1349             :              * Right now, we only consider grouping and aggregation beyond
    1350             :              * joins. Queries involving aggregates or grouping do not require
    1351             :              * EPQ mechanism, hence should not have an outer plan here.
    1352             :              */
    1353             :             Assert(!IS_UPPER_REL(foreignrel));
    1354             : 
    1355             :             /*
    1356             :              * First, update the plan's qual list if possible.  In some cases
    1357             :              * the quals might be enforced below the topmost plan level, in
    1358             :              * which case we'll fail to remove them; it's not worth working
    1359             :              * harder than this.
    1360             :              */
    1361          46 :             foreach(lc, local_exprs)
    1362             :             {
    1363           6 :                 Node       *qual = lfirst(lc);
    1364             : 
    1365           6 :                 outer_plan->qual = list_delete(outer_plan->qual, qual);
    1366             : 
    1367             :                 /*
    1368             :                  * For an inner join the local conditions of foreign scan plan
    1369             :                  * can be part of the joinquals as well.  (They might also be
    1370             :                  * in the mergequals or hashquals, but we can't touch those
    1371             :                  * without breaking the plan.)
    1372             :                  */
    1373           6 :                 if (IsA(outer_plan, NestLoop) ||
    1374           2 :                     IsA(outer_plan, MergeJoin) ||
    1375           2 :                     IsA(outer_plan, HashJoin))
    1376             :                 {
    1377           4 :                     Join       *join_plan = (Join *) outer_plan;
    1378             : 
    1379           4 :                     if (join_plan->jointype == JOIN_INNER)
    1380           4 :                         join_plan->joinqual = list_delete(join_plan->joinqual,
    1381             :                                                           qual);
    1382             :                 }
    1383             :             }
    1384             : 
    1385             :             /*
    1386             :              * Now fix the subplan's tlist --- this might result in inserting
    1387             :              * a Result node atop the plan tree.
    1388             :              */
    1389          40 :             outer_plan = change_plan_targetlist(outer_plan, fdw_scan_tlist,
    1390          40 :                                                 best_path->path.parallel_safe);
    1391             :         }
    1392             :     }
    1393             : 
    1394             :     /*
    1395             :      * Build the query string to be sent for execution, and identify
    1396             :      * expressions to be sent as parameters.
    1397             :      */
    1398        1902 :     initStringInfo(&sql);
    1399        1902 :     deparseSelectStmtForRel(&sql, root, foreignrel, fdw_scan_tlist,
    1400             :                             remote_exprs, best_path->path.pathkeys,
    1401             :                             has_final_sort, has_limit, false,
    1402             :                             &retrieved_attrs, &params_list);
    1403             : 
    1404             :     /* Remember remote_exprs for possible use by postgresPlanDirectModify */
    1405        1902 :     fpinfo->final_remote_exprs = remote_exprs;
    1406             : 
    1407             :     /*
    1408             :      * Build the fdw_private list that will be available to the executor.
    1409             :      * Items in the list must match order in enum FdwScanPrivateIndex.
    1410             :      */
    1411        1902 :     fdw_private = list_make3(makeString(sql.data),
    1412             :                              retrieved_attrs,
    1413             :                              makeInteger(fpinfo->fetch_size));
    1414        1902 :     if (IS_JOIN_REL(foreignrel) || IS_UPPER_REL(foreignrel))
    1415         540 :         fdw_private = lappend(fdw_private,
    1416         540 :                               makeString(fpinfo->relation_name));
    1417             : 
    1418             :     /*
    1419             :      * Create the ForeignScan node for the given relation.
    1420             :      *
    1421             :      * Note that the remote parameter expressions are stored in the fdw_exprs
    1422             :      * field of the finished plan node; we can't keep them in private state
    1423             :      * because then they wouldn't be subject to later planner processing.
    1424             :      */
    1425        1902 :     return make_foreignscan(tlist,
    1426             :                             local_exprs,
    1427             :                             scan_relid,
    1428             :                             params_list,
    1429             :                             fdw_private,
    1430             :                             fdw_scan_tlist,
    1431             :                             fdw_recheck_quals,
    1432             :                             outer_plan);
    1433             : }
    1434             : 
    1435             : /*
    1436             :  * Construct a tuple descriptor for the scan tuples handled by a foreign join.
    1437             :  */
    1438             : static TupleDesc
    1439         304 : get_tupdesc_for_join_scan_tuples(ForeignScanState *node)
    1440             : {
    1441         304 :     ForeignScan *fsplan = (ForeignScan *) node->ss.ps.plan;
    1442         304 :     EState     *estate = node->ss.ps.state;
    1443             :     TupleDesc   tupdesc;
    1444             : 
    1445             :     /*
    1446             :      * The core code has already set up a scan tuple slot based on
    1447             :      * fsplan->fdw_scan_tlist, and this slot's tupdesc is mostly good enough,
    1448             :      * but there's one case where it isn't.  If we have any whole-row row
    1449             :      * identifier Vars, they may have vartype RECORD, and we need to replace
    1450             :      * that with the associated table's actual composite type.  This ensures
    1451             :      * that when we read those ROW() expression values from the remote server,
    1452             :      * we can convert them to a composite type the local server knows.
    1453             :      */
    1454         304 :     tupdesc = CreateTupleDescCopy(node->ss.ss_ScanTupleSlot->tts_tupleDescriptor);
    1455        1270 :     for (int i = 0; i < tupdesc->natts; i++)
    1456             :     {
    1457         966 :         Form_pg_attribute att = TupleDescAttr(tupdesc, i);
    1458             :         Var        *var;
    1459             :         RangeTblEntry *rte;
    1460             :         Oid         reltype;
    1461             : 
    1462             :         /* Nothing to do if it's not a generic RECORD attribute */
    1463         966 :         if (att->atttypid != RECORDOID || att->atttypmod >= 0)
    1464         962 :             continue;
    1465             : 
    1466             :         /*
    1467             :          * If we can't identify the referenced table, do nothing.  This'll
    1468             :          * likely lead to failure later, but perhaps we can muddle through.
    1469             :          */
    1470           4 :         var = (Var *) list_nth_node(TargetEntry, fsplan->fdw_scan_tlist,
    1471             :                                     i)->expr;
    1472           4 :         if (!IsA(var, Var) || var->varattno != 0)
    1473           0 :             continue;
    1474           4 :         rte = list_nth(estate->es_range_table, var->varno - 1);
    1475           4 :         if (rte->rtekind != RTE_RELATION)
    1476           0 :             continue;
    1477           4 :         reltype = get_rel_type_id(rte->relid);
    1478           4 :         if (!OidIsValid(reltype))
    1479           0 :             continue;
    1480           4 :         att->atttypid = reltype;
    1481             :         /* shouldn't need to change anything else */
    1482             :     }
    1483         304 :     return tupdesc;
    1484             : }
    1485             : 
    1486             : /*
    1487             :  * postgresBeginForeignScan
    1488             :  *      Initiate an executor scan of a foreign PostgreSQL table.
    1489             :  */
    1490             : static void
    1491        1676 : postgresBeginForeignScan(ForeignScanState *node, int eflags)
    1492             : {
    1493        1676 :     ForeignScan *fsplan = (ForeignScan *) node->ss.ps.plan;
    1494        1676 :     EState     *estate = node->ss.ps.state;
    1495             :     PgFdwScanState *fsstate;
    1496             :     RangeTblEntry *rte;
    1497             :     Oid         userid;
    1498             :     ForeignTable *table;
    1499             :     UserMapping *user;
    1500             :     int         rtindex;
    1501             :     int         numParams;
    1502             : 
    1503             :     /*
    1504             :      * Do nothing in EXPLAIN (no ANALYZE) case.  node->fdw_state stays NULL.
    1505             :      */
    1506        1676 :     if (eflags & EXEC_FLAG_EXPLAIN_ONLY)
    1507         724 :         return;
    1508             : 
    1509             :     /*
    1510             :      * We'll save private state in node->fdw_state.
    1511             :      */
    1512         952 :     fsstate = (PgFdwScanState *) palloc0(sizeof(PgFdwScanState));
    1513         952 :     node->fdw_state = (void *) fsstate;
    1514             : 
    1515             :     /*
    1516             :      * Identify which user to do the remote access as.  This should match what
    1517             :      * ExecCheckPermissions() does.
    1518             :      */
    1519         952 :     userid = OidIsValid(fsplan->checkAsUser) ? fsplan->checkAsUser : GetUserId();
    1520         952 :     if (fsplan->scan.scanrelid > 0)
    1521         650 :         rtindex = fsplan->scan.scanrelid;
    1522             :     else
    1523         302 :         rtindex = bms_next_member(fsplan->fs_base_relids, -1);
    1524         952 :     rte = exec_rt_fetch(rtindex, estate);
    1525             : 
    1526             :     /* Get info about foreign table. */
    1527         952 :     table = GetForeignTable(rte->relid);
    1528         952 :     user = GetUserMapping(userid, table->serverid);
    1529             : 
    1530             :     /*
    1531             :      * Get connection to the foreign server.  Connection manager will
    1532             :      * establish new connection if necessary.
    1533             :      */
    1534         952 :     fsstate->conn = GetConnection(user, false, &fsstate->conn_state);
    1535             : 
    1536             :     /* Assign a unique ID for my cursor */
    1537         938 :     fsstate->cursor_number = GetCursorNumber(fsstate->conn);
    1538         938 :     fsstate->cursor_exists = false;
    1539             : 
    1540             :     /* Get private info created by planner functions. */
    1541         938 :     fsstate->query = strVal(list_nth(fsplan->fdw_private,
    1542             :                                      FdwScanPrivateSelectSql));
    1543         938 :     fsstate->retrieved_attrs = (List *) list_nth(fsplan->fdw_private,
    1544             :                                                  FdwScanPrivateRetrievedAttrs);
    1545         938 :     fsstate->fetch_size = intVal(list_nth(fsplan->fdw_private,
    1546             :                                           FdwScanPrivateFetchSize));
    1547             : 
    1548             :     /* Create contexts for batches of tuples and per-tuple temp workspace. */
    1549         938 :     fsstate->batch_cxt = AllocSetContextCreate(estate->es_query_cxt,
    1550             :                                                "postgres_fdw tuple data",
    1551             :                                                ALLOCSET_DEFAULT_SIZES);
    1552         938 :     fsstate->temp_cxt = AllocSetContextCreate(estate->es_query_cxt,
    1553             :                                               "postgres_fdw temporary data",
    1554             :                                               ALLOCSET_SMALL_SIZES);
    1555             : 
    1556             :     /*
    1557             :      * Get info we'll need for converting data fetched from the foreign server
    1558             :      * into local representation and error reporting during that process.
    1559             :      */
    1560         938 :     if (fsplan->scan.scanrelid > 0)
    1561             :     {
    1562         636 :         fsstate->rel = node->ss.ss_currentRelation;
    1563         636 :         fsstate->tupdesc = RelationGetDescr(fsstate->rel);
    1564             :     }
    1565             :     else
    1566             :     {
    1567         302 :         fsstate->rel = NULL;
    1568         302 :         fsstate->tupdesc = get_tupdesc_for_join_scan_tuples(node);
    1569             :     }
    1570             : 
    1571         938 :     fsstate->attinmeta = TupleDescGetAttInMetadata(fsstate->tupdesc);
    1572             : 
    1573             :     /*
    1574             :      * Prepare for processing of parameters used in remote query, if any.
    1575             :      */
    1576         938 :     numParams = list_length(fsplan->fdw_exprs);
    1577         938 :     fsstate->numParams = numParams;
    1578         938 :     if (numParams > 0)
    1579          36 :         prepare_query_params((PlanState *) node,
    1580             :                              fsplan->fdw_exprs,
    1581             :                              numParams,
    1582             :                              &fsstate->param_flinfo,
    1583             :                              &fsstate->param_exprs,
    1584             :                              &fsstate->param_values);
    1585             : 
    1586             :     /* Set the async-capable flag */
    1587         938 :     fsstate->async_capable = node->ss.ps.async_capable;
    1588             : }
    1589             : 
    1590             : /*
    1591             :  * postgresIterateForeignScan
    1592             :  *      Retrieve next row from the result set, or clear tuple slot to indicate
    1593             :  *      EOF.
    1594             :  */
    1595             : static TupleTableSlot *
    1596      137602 : postgresIterateForeignScan(ForeignScanState *node)
    1597             : {
    1598      137602 :     PgFdwScanState *fsstate = (PgFdwScanState *) node->fdw_state;
    1599      137602 :     TupleTableSlot *slot = node->ss.ss_ScanTupleSlot;
    1600             : 
    1601             :     /*
    1602             :      * In sync mode, if this is the first call after Begin or ReScan, we need
    1603             :      * to create the cursor on the remote side.  In async mode, we would have
    1604             :      * already created the cursor before we get here, even if this is the
    1605             :      * first call after Begin or ReScan.
    1606             :      */
    1607      137602 :     if (!fsstate->cursor_exists)
    1608        1482 :         create_cursor(node);
    1609             : 
    1610             :     /*
    1611             :      * Get some more tuples, if we've run out.
    1612             :      */
    1613      137598 :     if (fsstate->next_tuple >= fsstate->num_tuples)
    1614             :     {
    1615             :         /* In async mode, just clear tuple slot. */
    1616        3976 :         if (fsstate->async_capable)
    1617          64 :             return ExecClearTuple(slot);
    1618             :         /* No point in another fetch if we already detected EOF, though. */
    1619        3912 :         if (!fsstate->eof_reached)
    1620        2598 :             fetch_more_data(node);
    1621             :         /* If we didn't get any tuples, must be end of data. */
    1622        3902 :         if (fsstate->next_tuple >= fsstate->num_tuples)
    1623        1454 :             return ExecClearTuple(slot);
    1624             :     }
    1625             : 
    1626             :     /*
    1627             :      * Return the next tuple.
    1628             :      */
    1629      136070 :     ExecStoreHeapTuple(fsstate->tuples[fsstate->next_tuple++],
    1630             :                        slot,
    1631             :                        false);
    1632             : 
    1633      136070 :     return slot;
    1634             : }
    1635             : 
    1636             : /*
    1637             :  * postgresReScanForeignScan
    1638             :  *      Restart the scan.
    1639             :  */
    1640             : static void
    1641         798 : postgresReScanForeignScan(ForeignScanState *node)
    1642             : {
    1643         798 :     PgFdwScanState *fsstate = (PgFdwScanState *) node->fdw_state;
    1644             :     char        sql[64];
    1645             :     PGresult   *res;
    1646             : 
    1647             :     /* If we haven't created the cursor yet, nothing to do. */
    1648         798 :     if (!fsstate->cursor_exists)
    1649          86 :         return;
    1650             : 
    1651             :     /*
    1652             :      * If the node is async-capable, and an asynchronous fetch for it has
    1653             :      * begun, the asynchronous fetch might not have yet completed.  Check if
    1654             :      * the node is async-capable, and an asynchronous fetch for it is still in
    1655             :      * progress; if so, complete the asynchronous fetch before restarting the
    1656             :      * scan.
    1657             :      */
    1658         736 :     if (fsstate->async_capable &&
    1659          42 :         fsstate->conn_state->pendingAreq &&
    1660           4 :         fsstate->conn_state->pendingAreq->requestee == (PlanState *) node)
    1661           2 :         fetch_more_data(node);
    1662             : 
    1663             :     /*
    1664             :      * If any internal parameters affecting this node have changed, we'd
    1665             :      * better destroy and recreate the cursor.  Otherwise, rewinding it should
    1666             :      * be good enough.  If we've only fetched zero or one batch, we needn't
    1667             :      * even rewind the cursor, just rescan what we have.
    1668             :      */
    1669         736 :     if (node->ss.ps.chgParam != NULL)
    1670             :     {
    1671         676 :         fsstate->cursor_exists = false;
    1672         676 :         snprintf(sql, sizeof(sql), "CLOSE c%u",
    1673             :                  fsstate->cursor_number);
    1674             :     }
    1675          60 :     else if (fsstate->fetch_ct_2 > 1)
    1676             :     {
    1677          36 :         snprintf(sql, sizeof(sql), "MOVE BACKWARD ALL IN c%u",
    1678             :                  fsstate->cursor_number);
    1679             :     }
    1680             :     else
    1681             :     {
    1682             :         /* Easy: just rescan what we already have in memory, if anything */
    1683          24 :         fsstate->next_tuple = 0;
    1684          24 :         return;
    1685             :     }
    1686             : 
    1687             :     /*
    1688             :      * We don't use a PG_TRY block here, so be careful not to throw error
    1689             :      * without releasing the PGresult.
    1690             :      */
    1691         712 :     res = pgfdw_exec_query(fsstate->conn, sql, fsstate->conn_state);
    1692         712 :     if (PQresultStatus(res) != PGRES_COMMAND_OK)
    1693           0 :         pgfdw_report_error(ERROR, res, fsstate->conn, true, sql);
    1694         712 :     PQclear(res);
    1695             : 
    1696             :     /* Now force a fresh FETCH. */
    1697         712 :     fsstate->tuples = NULL;
    1698         712 :     fsstate->num_tuples = 0;
    1699         712 :     fsstate->next_tuple = 0;
    1700         712 :     fsstate->fetch_ct_2 = 0;
    1701         712 :     fsstate->eof_reached = false;
    1702             : }
    1703             : 
    1704             : /*
    1705             :  * postgresEndForeignScan
    1706             :  *      Finish scanning foreign table and dispose objects used for this scan
    1707             :  */
    1708             : static void
    1709        1630 : postgresEndForeignScan(ForeignScanState *node)
    1710             : {
    1711        1630 :     PgFdwScanState *fsstate = (PgFdwScanState *) node->fdw_state;
    1712             : 
    1713             :     /* if fsstate is NULL, we are in EXPLAIN; nothing to do */
    1714        1630 :     if (fsstate == NULL)
    1715         724 :         return;
    1716             : 
    1717             :     /* Close the cursor if open, to prevent accumulation of cursors */
    1718         906 :     if (fsstate->cursor_exists)
    1719         876 :         close_cursor(fsstate->conn, fsstate->cursor_number,
    1720             :                      fsstate->conn_state);
    1721             : 
    1722             :     /* Release remote connection */
    1723         906 :     ReleaseConnection(fsstate->conn);
    1724         906 :     fsstate->conn = NULL;
    1725             : 
    1726             :     /* MemoryContexts will be deleted automatically. */
    1727             : }
    1728             : 
    1729             : /*
    1730             :  * postgresAddForeignUpdateTargets
    1731             :  *      Add resjunk column(s) needed for update/delete on a foreign table
    1732             :  */
    1733             : static void
    1734         344 : postgresAddForeignUpdateTargets(PlannerInfo *root,
    1735             :                                 Index rtindex,
    1736             :                                 RangeTblEntry *target_rte,
    1737             :                                 Relation target_relation)
    1738             : {
    1739             :     Var        *var;
    1740             : 
    1741             :     /*
    1742             :      * In postgres_fdw, what we need is the ctid, same as for a regular table.
    1743             :      */
    1744             : 
    1745             :     /* Make a Var representing the desired value */
    1746         344 :     var = makeVar(rtindex,
    1747             :                   SelfItemPointerAttributeNumber,
    1748             :                   TIDOID,
    1749             :                   -1,
    1750             :                   InvalidOid,
    1751             :                   0);
    1752             : 
    1753             :     /* Register it as a row-identity column needed by this target rel */
    1754         344 :     add_row_identity_var(root, var, rtindex, "ctid");
    1755         344 : }
    1756             : 
    1757             : /*
    1758             :  * postgresPlanForeignModify
    1759             :  *      Plan an insert/update/delete operation on a foreign table
    1760             :  */
    1761             : static List *
    1762         306 : postgresPlanForeignModify(PlannerInfo *root,
    1763             :                           ModifyTable *plan,
    1764             :                           Index resultRelation,
    1765             :                           int subplan_index)
    1766             : {
    1767         306 :     CmdType     operation = plan->operation;
    1768         306 :     RangeTblEntry *rte = planner_rt_fetch(resultRelation, root);
    1769             :     Relation    rel;
    1770             :     StringInfoData sql;
    1771         306 :     List       *targetAttrs = NIL;
    1772         306 :     List       *withCheckOptionList = NIL;
    1773         306 :     List       *returningList = NIL;
    1774         306 :     List       *retrieved_attrs = NIL;
    1775         306 :     bool        doNothing = false;
    1776         306 :     int         values_end_len = -1;
    1777             : 
    1778         306 :     initStringInfo(&sql);
    1779             : 
    1780             :     /*
    1781             :      * Core code already has some lock on each rel being planned, so we can
    1782             :      * use NoLock here.
    1783             :      */
    1784         306 :     rel = table_open(rte->relid, NoLock);
    1785             : 
    1786             :     /*
    1787             :      * In an INSERT, we transmit all columns that are defined in the foreign
    1788             :      * table.  In an UPDATE, if there are BEFORE ROW UPDATE triggers on the
    1789             :      * foreign table, we transmit all columns like INSERT; else we transmit
    1790             :      * only columns that were explicitly targets of the UPDATE, so as to avoid
    1791             :      * unnecessary data transmission.  (We can't do that for INSERT since we
    1792             :      * would miss sending default values for columns not listed in the source
    1793             :      * statement, and for UPDATE if there are BEFORE ROW UPDATE triggers since
    1794             :      * those triggers might change values for non-target columns, in which
    1795             :      * case we would miss sending changed values for those columns.)
    1796             :      */
    1797         306 :     if (operation == CMD_INSERT ||
    1798         100 :         (operation == CMD_UPDATE &&
    1799         100 :          rel->trigdesc &&
    1800          36 :          rel->trigdesc->trig_update_before_row))
    1801         204 :     {
    1802         204 :         TupleDesc   tupdesc = RelationGetDescr(rel);
    1803             :         int         attnum;
    1804             : 
    1805         854 :         for (attnum = 1; attnum <= tupdesc->natts; attnum++)
    1806             :         {
    1807         650 :             Form_pg_attribute attr = TupleDescAttr(tupdesc, attnum - 1);
    1808             : 
    1809         650 :             if (!attr->attisdropped)
    1810         616 :                 targetAttrs = lappend_int(targetAttrs, attnum);
    1811             :         }
    1812             :     }
    1813         102 :     else if (operation == CMD_UPDATE)
    1814             :     {
    1815             :         int         col;
    1816          70 :         RelOptInfo *rel = find_base_rel(root, resultRelation);
    1817          70 :         Bitmapset  *allUpdatedCols = get_rel_all_updated_cols(root, rel);
    1818             : 
    1819          70 :         col = -1;
    1820         152 :         while ((col = bms_next_member(allUpdatedCols, col)) >= 0)
    1821             :         {
    1822             :             /* bit numbers are offset by FirstLowInvalidHeapAttributeNumber */
    1823          82 :             AttrNumber  attno = col + FirstLowInvalidHeapAttributeNumber;
    1824             : 
    1825          82 :             if (attno <= InvalidAttrNumber) /* shouldn't happen */
    1826           0 :                 elog(ERROR, "system-column update is not supported");
    1827          82 :             targetAttrs = lappend_int(targetAttrs, attno);
    1828             :         }
    1829             :     }
    1830             : 
    1831             :     /*
    1832             :      * Extract the relevant WITH CHECK OPTION list if any.
    1833             :      */
    1834         306 :     if (plan->withCheckOptionLists)
    1835          32 :         withCheckOptionList = (List *) list_nth(plan->withCheckOptionLists,
    1836             :                                                 subplan_index);
    1837             : 
    1838             :     /*
    1839             :      * Extract the relevant RETURNING list if any.
    1840             :      */
    1841         306 :     if (plan->returningLists)
    1842          48 :         returningList = (List *) list_nth(plan->returningLists, subplan_index);
    1843             : 
    1844             :     /*
    1845             :      * ON CONFLICT DO UPDATE and DO NOTHING case with inference specification
    1846             :      * should have already been rejected in the optimizer, as presently there
    1847             :      * is no way to recognize an arbiter index on a foreign table.  Only DO
    1848             :      * NOTHING is supported without an inference specification.
    1849             :      */
    1850         306 :     if (plan->onConflictAction == ONCONFLICT_NOTHING)
    1851           2 :         doNothing = true;
    1852         304 :     else if (plan->onConflictAction != ONCONFLICT_NONE)
    1853           0 :         elog(ERROR, "unexpected ON CONFLICT specification: %d",
    1854             :              (int) plan->onConflictAction);
    1855             : 
    1856             :     /*
    1857             :      * Construct the SQL command string.
    1858             :      */
    1859         306 :     switch (operation)
    1860             :     {
    1861         174 :         case CMD_INSERT:
    1862         174 :             deparseInsertSql(&sql, rte, resultRelation, rel,
    1863             :                              targetAttrs, doNothing,
    1864             :                              withCheckOptionList, returningList,
    1865             :                              &retrieved_attrs, &values_end_len);
    1866         174 :             break;
    1867         100 :         case CMD_UPDATE:
    1868         100 :             deparseUpdateSql(&sql, rte, resultRelation, rel,
    1869             :                              targetAttrs,
    1870             :                              withCheckOptionList, returningList,
    1871             :                              &retrieved_attrs);
    1872         100 :             break;
    1873          32 :         case CMD_DELETE:
    1874          32 :             deparseDeleteSql(&sql, rte, resultRelation, rel,
    1875             :                              returningList,
    1876             :                              &retrieved_attrs);
    1877          32 :             break;
    1878           0 :         default:
    1879           0 :             elog(ERROR, "unexpected operation: %d", (int) operation);
    1880             :             break;
    1881             :     }
    1882             : 
    1883         306 :     table_close(rel, NoLock);
    1884             : 
    1885             :     /*
    1886             :      * Build the fdw_private list that will be available to the executor.
    1887             :      * Items in the list must match enum FdwModifyPrivateIndex, above.
    1888             :      */
    1889         306 :     return list_make5(makeString(sql.data),
    1890             :                       targetAttrs,
    1891             :                       makeInteger(values_end_len),
    1892             :                       makeBoolean((retrieved_attrs != NIL)),
    1893             :                       retrieved_attrs);
    1894             : }
    1895             : 
    1896             : /*
    1897             :  * postgresBeginForeignModify
    1898             :  *      Begin an insert/update/delete operation on a foreign table
    1899             :  */
    1900             : static void
    1901         306 : postgresBeginForeignModify(ModifyTableState *mtstate,
    1902             :                            ResultRelInfo *resultRelInfo,
    1903             :                            List *fdw_private,
    1904             :                            int subplan_index,
    1905             :                            int eflags)
    1906             : {
    1907             :     PgFdwModifyState *fmstate;
    1908             :     char       *query;
    1909             :     List       *target_attrs;
    1910             :     bool        has_returning;
    1911             :     int         values_end_len;
    1912             :     List       *retrieved_attrs;
    1913             :     RangeTblEntry *rte;
    1914             : 
    1915             :     /*
    1916             :      * Do nothing in EXPLAIN (no ANALYZE) case.  resultRelInfo->ri_FdwState
    1917             :      * stays NULL.
    1918             :      */
    1919         306 :     if (eflags & EXEC_FLAG_EXPLAIN_ONLY)
    1920          76 :         return;
    1921             : 
    1922             :     /* Deconstruct fdw_private data. */
    1923         230 :     query = strVal(list_nth(fdw_private,
    1924             :                             FdwModifyPrivateUpdateSql));
    1925         230 :     target_attrs = (List *) list_nth(fdw_private,
    1926             :                                      FdwModifyPrivateTargetAttnums);
    1927         230 :     values_end_len = intVal(list_nth(fdw_private,
    1928             :                                      FdwModifyPrivateLen));
    1929         230 :     has_returning = boolVal(list_nth(fdw_private,
    1930             :                                      FdwModifyPrivateHasReturning));
    1931         230 :     retrieved_attrs = (List *) list_nth(fdw_private,
    1932             :                                         FdwModifyPrivateRetrievedAttrs);
    1933             : 
    1934             :     /* Find RTE. */
    1935         230 :     rte = exec_rt_fetch(resultRelInfo->ri_RangeTableIndex,
    1936             :                         mtstate->ps.state);
    1937             : 
    1938             :     /* Construct an execution state. */
    1939         230 :     fmstate = create_foreign_modify(mtstate->ps.state,
    1940             :                                     rte,
    1941             :                                     resultRelInfo,
    1942             :                                     mtstate->operation,
    1943         230 :                                     outerPlanState(mtstate)->plan,
    1944             :                                     query,
    1945             :                                     target_attrs,
    1946             :                                     values_end_len,
    1947             :                                     has_returning,
    1948             :                                     retrieved_attrs);
    1949             : 
    1950         230 :     resultRelInfo->ri_FdwState = fmstate;
    1951             : }
    1952             : 
    1953             : /*
    1954             :  * postgresExecForeignInsert
    1955             :  *      Insert one row into a foreign table
    1956             :  */
    1957             : static TupleTableSlot *
    1958        1776 : postgresExecForeignInsert(EState *estate,
    1959             :                           ResultRelInfo *resultRelInfo,
    1960             :                           TupleTableSlot *slot,
    1961             :                           TupleTableSlot *planSlot)
    1962             : {
    1963        1776 :     PgFdwModifyState *fmstate = (PgFdwModifyState *) resultRelInfo->ri_FdwState;
    1964             :     TupleTableSlot **rslot;
    1965        1776 :     int         numSlots = 1;
    1966             : 
    1967             :     /*
    1968             :      * If the fmstate has aux_fmstate set, use the aux_fmstate (see
    1969             :      * postgresBeginForeignInsert())
    1970             :      */
    1971        1776 :     if (fmstate->aux_fmstate)
    1972           0 :         resultRelInfo->ri_FdwState = fmstate->aux_fmstate;
    1973        1776 :     rslot = execute_foreign_modify(estate, resultRelInfo, CMD_INSERT,
    1974             :                                    &slot, &planSlot, &numSlots);
    1975             :     /* Revert that change */
    1976        1768 :     if (fmstate->aux_fmstate)
    1977           0 :         resultRelInfo->ri_FdwState = fmstate;
    1978             : 
    1979        1768 :     return rslot ? *rslot : NULL;
    1980             : }
    1981             : 
    1982             : /*
    1983             :  * postgresExecForeignBatchInsert
    1984             :  *      Insert multiple rows into a foreign table
    1985             :  */
    1986             : static TupleTableSlot **
    1987          82 : postgresExecForeignBatchInsert(EState *estate,
    1988             :                                ResultRelInfo *resultRelInfo,
    1989             :                                TupleTableSlot **slots,
    1990             :                                TupleTableSlot **planSlots,
    1991             :                                int *numSlots)
    1992             : {
    1993          82 :     PgFdwModifyState *fmstate = (PgFdwModifyState *) resultRelInfo->ri_FdwState;
    1994             :     TupleTableSlot **rslot;
    1995             : 
    1996             :     /*
    1997             :      * If the fmstate has aux_fmstate set, use the aux_fmstate (see
    1998             :      * postgresBeginForeignInsert())
    1999             :      */
    2000          82 :     if (fmstate->aux_fmstate)
    2001           0 :         resultRelInfo->ri_FdwState = fmstate->aux_fmstate;
    2002          82 :     rslot = execute_foreign_modify(estate, resultRelInfo, CMD_INSERT,
    2003             :                                    slots, planSlots, numSlots);
    2004             :     /* Revert that change */
    2005          80 :     if (fmstate->aux_fmstate)
    2006           0 :         resultRelInfo->ri_FdwState = fmstate;
    2007             : 
    2008          80 :     return rslot;
    2009             : }
    2010             : 
    2011             : /*
    2012             :  * postgresGetForeignModifyBatchSize
    2013             :  *      Determine the maximum number of tuples that can be inserted in bulk
    2014             :  *
    2015             :  * Returns the batch size specified for server or table. When batching is not
    2016             :  * allowed (e.g. for tables with BEFORE/AFTER ROW triggers or with RETURNING
    2017             :  * clause), returns 1.
    2018             :  */
    2019             : static int
    2020         282 : postgresGetForeignModifyBatchSize(ResultRelInfo *resultRelInfo)
    2021             : {
    2022             :     int         batch_size;
    2023         282 :     PgFdwModifyState *fmstate = (PgFdwModifyState *) resultRelInfo->ri_FdwState;
    2024             : 
    2025             :     /* should be called only once */
    2026             :     Assert(resultRelInfo->ri_BatchSize == 0);
    2027             : 
    2028             :     /*
    2029             :      * Should never get called when the insert is being performed on a table
    2030             :      * that is also among the target relations of an UPDATE operation, because
    2031             :      * postgresBeginForeignInsert() currently rejects such insert attempts.
    2032             :      */
    2033             :     Assert(fmstate == NULL || fmstate->aux_fmstate == NULL);
    2034             : 
    2035             :     /*
    2036             :      * In EXPLAIN without ANALYZE, ri_FdwState is NULL, so we have to lookup
    2037             :      * the option directly in server/table options. Otherwise just use the
    2038             :      * value we determined earlier.
    2039             :      */
    2040         282 :     if (fmstate)
    2041         256 :         batch_size = fmstate->batch_size;
    2042             :     else
    2043          26 :         batch_size = get_batch_size_option(resultRelInfo->ri_RelationDesc);
    2044             : 
    2045             :     /*
    2046             :      * Disable batching when we have to use RETURNING, there are any
    2047             :      * BEFORE/AFTER ROW INSERT triggers on the foreign table, or there are any
    2048             :      * WITH CHECK OPTION constraints from parent views.
    2049             :      *
    2050             :      * When there are any BEFORE ROW INSERT triggers on the table, we can't
    2051             :      * support it, because such triggers might query the table we're inserting
    2052             :      * into and act differently if the tuples that have already been processed
    2053             :      * and prepared for insertion are not there.
    2054             :      */
    2055         282 :     if (resultRelInfo->ri_projectReturning != NULL ||
    2056         240 :         resultRelInfo->ri_WithCheckOptions != NIL ||
    2057         222 :         (resultRelInfo->ri_TrigDesc &&
    2058          28 :          (resultRelInfo->ri_TrigDesc->trig_insert_before_row ||
    2059           2 :           resultRelInfo->ri_TrigDesc->trig_insert_after_row)))
    2060          88 :         return 1;
    2061             : 
    2062             :     /*
    2063             :      * If the foreign table has no columns, disable batching as the INSERT
    2064             :      * syntax doesn't allow batching multiple empty rows into a zero-column
    2065             :      * table in a single statement.  This is needed for COPY FROM, in which
    2066             :      * case fmstate must be non-NULL.
    2067             :      */
    2068         194 :     if (fmstate && list_length(fmstate->target_attrs) == 0)
    2069           2 :         return 1;
    2070             : 
    2071             :     /*
    2072             :      * Otherwise use the batch size specified for server/table. The number of
    2073             :      * parameters in a batch is limited to 65535 (uint16), so make sure we
    2074             :      * don't exceed this limit by using the maximum batch_size possible.
    2075             :      */
    2076         192 :     if (fmstate && fmstate->p_nums > 0)
    2077         176 :         batch_size = Min(batch_size, PQ_QUERY_PARAM_MAX_LIMIT / fmstate->p_nums);
    2078             : 
    2079         192 :     return batch_size;
    2080             : }
    2081             : 
    2082             : /*
    2083             :  * postgresExecForeignUpdate
    2084             :  *      Update one row in a foreign table
    2085             :  */
    2086             : static TupleTableSlot *
    2087         142 : postgresExecForeignUpdate(EState *estate,
    2088             :                           ResultRelInfo *resultRelInfo,
    2089             :                           TupleTableSlot *slot,
    2090             :                           TupleTableSlot *planSlot)
    2091             : {
    2092             :     TupleTableSlot **rslot;
    2093         142 :     int         numSlots = 1;
    2094             : 
    2095         142 :     rslot = execute_foreign_modify(estate, resultRelInfo, CMD_UPDATE,
    2096             :                                    &slot, &planSlot, &numSlots);
    2097             : 
    2098         142 :     return rslot ? rslot[0] : NULL;
    2099             : }
    2100             : 
    2101             : /*
    2102             :  * postgresExecForeignDelete
    2103             :  *      Delete one row from a foreign table
    2104             :  */
    2105             : static TupleTableSlot *
    2106          34 : postgresExecForeignDelete(EState *estate,
    2107             :                           ResultRelInfo *resultRelInfo,
    2108             :                           TupleTableSlot *slot,
    2109             :                           TupleTableSlot *planSlot)
    2110             : {
    2111             :     TupleTableSlot **rslot;
    2112          34 :     int         numSlots = 1;
    2113             : 
    2114          34 :     rslot = execute_foreign_modify(estate, resultRelInfo, CMD_DELETE,
    2115             :                                    &slot, &planSlot, &numSlots);
    2116             : 
    2117          34 :     return rslot ? rslot[0] : NULL;
    2118             : }
    2119             : 
    2120             : /*
    2121             :  * postgresEndForeignModify
    2122             :  *      Finish an insert/update/delete operation on a foreign table
    2123             :  */
    2124             : static void
    2125         286 : postgresEndForeignModify(EState *estate,
    2126             :                          ResultRelInfo *resultRelInfo)
    2127             : {
    2128         286 :     PgFdwModifyState *fmstate = (PgFdwModifyState *) resultRelInfo->ri_FdwState;
    2129             : 
    2130             :     /* If fmstate is NULL, we are in EXPLAIN; nothing to do */
    2131         286 :     if (fmstate == NULL)
    2132          76 :         return;
    2133             : 
    2134             :     /* Destroy the execution state */
    2135         210 :     finish_foreign_modify(fmstate);
    2136             : }
    2137             : 
    2138             : /*
    2139             :  * postgresBeginForeignInsert
    2140             :  *      Begin an insert operation on a foreign table
    2141             :  */
    2142             : static void
    2143         120 : postgresBeginForeignInsert(ModifyTableState *mtstate,
    2144             :                            ResultRelInfo *resultRelInfo)
    2145             : {
    2146             :     PgFdwModifyState *fmstate;
    2147         120 :     ModifyTable *plan = castNode(ModifyTable, mtstate->ps.plan);
    2148         120 :     EState     *estate = mtstate->ps.state;
    2149             :     Index       resultRelation;
    2150         120 :     Relation    rel = resultRelInfo->ri_RelationDesc;
    2151             :     RangeTblEntry *rte;
    2152         120 :     TupleDesc   tupdesc = RelationGetDescr(rel);
    2153             :     int         attnum;
    2154             :     int         values_end_len;
    2155             :     StringInfoData sql;
    2156         120 :     List       *targetAttrs = NIL;
    2157         120 :     List       *retrieved_attrs = NIL;
    2158         120 :     bool        doNothing = false;
    2159             : 
    2160             :     /*
    2161             :      * If the foreign table we are about to insert routed rows into is also an
    2162             :      * UPDATE subplan result rel that will be updated later, proceeding with
    2163             :      * the INSERT will result in the later UPDATE incorrectly modifying those
    2164             :      * routed rows, so prevent the INSERT --- it would be nice if we could
    2165             :      * handle this case; but for now, throw an error for safety.
    2166             :      */
    2167         120 :     if (plan && plan->operation == CMD_UPDATE &&
    2168          18 :         (resultRelInfo->ri_usesFdwDirectModify ||
    2169          10 :          resultRelInfo->ri_FdwState))
    2170          12 :         ereport(ERROR,
    2171             :                 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
    2172             :                  errmsg("cannot route tuples into foreign table to be updated \"%s\"",
    2173             :                         RelationGetRelationName(rel))));
    2174             : 
    2175         108 :     initStringInfo(&sql);
    2176             : 
    2177             :     /* We transmit all columns that are defined in the foreign table. */
    2178         320 :     for (attnum = 1; attnum <= tupdesc->natts; attnum++)
    2179             :     {
    2180         212 :         Form_pg_attribute attr = TupleDescAttr(tupdesc, attnum - 1);
    2181             : 
    2182         212 :         if (!attr->attisdropped)
    2183         208 :             targetAttrs = lappend_int(targetAttrs, attnum);
    2184             :     }
    2185             : 
    2186             :     /* Check if we add the ON CONFLICT clause to the remote query. */
    2187         108 :     if (plan)
    2188             :     {
    2189          64 :         OnConflictAction onConflictAction = plan->onConflictAction;
    2190             : 
    2191             :         /* We only support DO NOTHING without an inference specification. */
    2192          64 :         if (onConflictAction == ONCONFLICT_NOTHING)
    2193           4 :             doNothing = true;
    2194          60 :         else if (onConflictAction != ONCONFLICT_NONE)
    2195           0 :             elog(ERROR, "unexpected ON CONFLICT specification: %d",
    2196             :                  (int) onConflictAction);
    2197             :     }
    2198             : 
    2199             :     /*
    2200             :      * If the foreign table is a partition that doesn't have a corresponding
    2201             :      * RTE entry, we need to create a new RTE describing the foreign table for
    2202             :      * use by deparseInsertSql and create_foreign_modify() below, after first
    2203             :      * copying the parent's RTE and modifying some fields to describe the
    2204             :      * foreign partition to work on. However, if this is invoked by UPDATE,
    2205             :      * the existing RTE may already correspond to this partition if it is one
    2206             :      * of the UPDATE subplan target rels; in that case, we can just use the
    2207             :      * existing RTE as-is.
    2208             :      */
    2209         108 :     if (resultRelInfo->ri_RangeTableIndex == 0)
    2210             :     {
    2211          72 :         ResultRelInfo *rootResultRelInfo = resultRelInfo->ri_RootResultRelInfo;
    2212             : 
    2213          72 :         rte = exec_rt_fetch(rootResultRelInfo->ri_RangeTableIndex, estate);
    2214          72 :         rte = copyObject(rte);
    2215          72 :         rte->relid = RelationGetRelid(rel);
    2216          72 :         rte->relkind = RELKIND_FOREIGN_TABLE;
    2217             : 
    2218             :         /*
    2219             :          * For UPDATE, we must use the RT index of the first subplan target
    2220             :          * rel's RTE, because the core code would have built expressions for
    2221             :          * the partition, such as RETURNING, using that RT index as varno of
    2222             :          * Vars contained in those expressions.
    2223             :          */
    2224          72 :         if (plan && plan->operation == CMD_UPDATE &&
    2225           6 :             rootResultRelInfo->ri_RangeTableIndex == plan->rootRelation)
    2226           6 :             resultRelation = mtstate->resultRelInfo[0].ri_RangeTableIndex;
    2227             :         else
    2228          66 :             resultRelation = rootResultRelInfo->ri_RangeTableIndex;
    2229             :     }
    2230             :     else
    2231             :     {
    2232          36 :         resultRelation = resultRelInfo->ri_RangeTableIndex;
    2233          36 :         rte = exec_rt_fetch(resultRelation, estate);
    2234             :     }
    2235             : 
    2236             :     /* Construct the SQL command string. */
    2237         108 :     deparseInsertSql(&sql, rte, resultRelation, rel, targetAttrs, doNothing,
    2238             :                      resultRelInfo->ri_WithCheckOptions,
    2239             :                      resultRelInfo->ri_returningList,
    2240             :                      &retrieved_attrs, &values_end_len);
    2241             : 
    2242             :     /* Construct an execution state. */
    2243         108 :     fmstate = create_foreign_modify(mtstate->ps.state,
    2244             :                                     rte,
    2245             :                                     resultRelInfo,
    2246             :                                     CMD_INSERT,
    2247             :                                     NULL,
    2248             :                                     sql.data,
    2249             :                                     targetAttrs,
    2250             :                                     values_end_len,
    2251             :                                     retrieved_attrs != NIL,
    2252             :                                     retrieved_attrs);
    2253             : 
    2254             :     /*
    2255             :      * If the given resultRelInfo already has PgFdwModifyState set, it means
    2256             :      * the foreign table is an UPDATE subplan result rel; in which case, store
    2257             :      * the resulting state into the aux_fmstate of the PgFdwModifyState.
    2258             :      */
    2259         108 :     if (resultRelInfo->ri_FdwState)
    2260             :     {
    2261             :         Assert(plan && plan->operation == CMD_UPDATE);
    2262             :         Assert(resultRelInfo->ri_usesFdwDirectModify == false);
    2263           0 :         ((PgFdwModifyState *) resultRelInfo->ri_FdwState)->aux_fmstate = fmstate;
    2264             :     }
    2265             :     else
    2266         108 :         resultRelInfo->ri_FdwState = fmstate;
    2267         108 : }
    2268             : 
    2269             : /*
    2270             :  * postgresEndForeignInsert
    2271             :  *      Finish an insert operation on a foreign table
    2272             :  */
    2273             : static void
    2274         100 : postgresEndForeignInsert(EState *estate,
    2275             :                          ResultRelInfo *resultRelInfo)
    2276             : {
    2277         100 :     PgFdwModifyState *fmstate = (PgFdwModifyState *) resultRelInfo->ri_FdwState;
    2278             : 
    2279             :     Assert(fmstate != NULL);
    2280             : 
    2281             :     /*
    2282             :      * If the fmstate has aux_fmstate set, get the aux_fmstate (see
    2283             :      * postgresBeginForeignInsert())
    2284             :      */
    2285         100 :     if (fmstate->aux_fmstate)
    2286           0 :         fmstate = fmstate->aux_fmstate;
    2287             : 
    2288             :     /* Destroy the execution state */
    2289         100 :     finish_foreign_modify(fmstate);
    2290         100 : }
    2291             : 
    2292             : /*
    2293             :  * postgresIsForeignRelUpdatable
    2294             :  *      Determine whether a foreign table supports INSERT, UPDATE and/or
    2295             :  *      DELETE.
    2296             :  */
    2297             : static int
    2298         634 : postgresIsForeignRelUpdatable(Relation rel)
    2299             : {
    2300             :     bool        updatable;
    2301             :     ForeignTable *table;
    2302             :     ForeignServer *server;
    2303             :     ListCell   *lc;
    2304             : 
    2305             :     /*
    2306             :      * By default, all postgres_fdw foreign tables are assumed updatable. This
    2307             :      * can be overridden by a per-server setting, which in turn can be
    2308             :      * overridden by a per-table setting.
    2309             :      */
    2310         634 :     updatable = true;
    2311             : 
    2312         634 :     table = GetForeignTable(RelationGetRelid(rel));
    2313         634 :     server = GetForeignServer(table->serverid);
    2314             : 
    2315        2850 :     foreach(lc, server->options)
    2316             :     {
    2317        2216 :         DefElem    *def = (DefElem *) lfirst(lc);
    2318             : 
    2319        2216 :         if (strcmp(def->defname, "updatable") == 0)
    2320           0 :             updatable = defGetBoolean(def);
    2321             :     }
    2322        1520 :     foreach(lc, table->options)
    2323             :     {
    2324         886 :         DefElem    *def = (DefElem *) lfirst(lc);
    2325             : 
    2326         886 :         if (strcmp(def->defname, "updatable") == 0)
    2327           0 :             updatable = defGetBoolean(def);
    2328             :     }
    2329             : 
    2330             :     /*
    2331             :      * Currently "updatable" means support for INSERT, UPDATE and DELETE.
    2332             :      */
    2333             :     return updatable ?
    2334         634 :         (1 << CMD_INSERT) | (1 << CMD_UPDATE) | (1 << CMD_DELETE) : 0;
    2335             : }
    2336             : 
    2337             : /*
    2338             :  * postgresRecheckForeignScan
    2339             :  *      Execute a local join execution plan for a foreign join
    2340             :  */
    2341             : static bool
    2342           0 : postgresRecheckForeignScan(ForeignScanState *node, TupleTableSlot *slot)
    2343             : {
    2344           0 :     Index       scanrelid = ((Scan *) node->ss.ps.plan)->scanrelid;
    2345           0 :     PlanState  *outerPlan = outerPlanState(node);
    2346             :     TupleTableSlot *result;
    2347             : 
    2348             :     /* For base foreign relations, it suffices to set fdw_recheck_quals */
    2349           0 :     if (scanrelid > 0)
    2350           0 :         return true;
    2351             : 
    2352             :     Assert(outerPlan != NULL);
    2353             : 
    2354             :     /* Execute a local join execution plan */
    2355           0 :     result = ExecProcNode(outerPlan);
    2356           0 :     if (TupIsNull(result))
    2357           0 :         return false;
    2358             : 
    2359             :     /* Store result in the given slot */
    2360           0 :     ExecCopySlot(slot, result);
    2361             : 
    2362           0 :     return true;
    2363             : }
    2364             : 
    2365             : /*
    2366             :  * find_modifytable_subplan
    2367             :  *      Helper routine for postgresPlanDirectModify to find the
    2368             :  *      ModifyTable subplan node that scans the specified RTI.
    2369             :  *
    2370             :  * Returns NULL if the subplan couldn't be identified.  That's not a fatal
    2371             :  * error condition, we just abandon trying to do the update directly.
    2372             :  */
    2373             : static ForeignScan *
    2374         258 : find_modifytable_subplan(PlannerInfo *root,
    2375             :                          ModifyTable *plan,
    2376             :                          Index rtindex,
    2377             :                          int subplan_index)
    2378             : {
    2379         258 :     Plan       *subplan = outerPlan(plan);
    2380             : 
    2381             :     /*
    2382             :      * The cases we support are (1) the desired ForeignScan is the immediate
    2383             :      * child of ModifyTable, or (2) it is the subplan_index'th child of an
    2384             :      * Append node that is the immediate child of ModifyTable.  There is no
    2385             :      * point in looking further down, as that would mean that local joins are
    2386             :      * involved, so we can't do the update directly.
    2387             :      *
    2388             :      * There could be a Result atop the Append too, acting to compute the
    2389             :      * UPDATE targetlist values.  We ignore that here; the tlist will be
    2390             :      * checked by our caller.
    2391             :      *
    2392             :      * In principle we could examine all the children of the Append, but it's
    2393             :      * currently unlikely that the core planner would generate such a plan
    2394             :      * with the children out-of-order.  Moreover, such a search risks costing
    2395             :      * O(N^2) time when there are a lot of children.
    2396             :      */
    2397         258 :     if (IsA(subplan, Append))
    2398             :     {
    2399          66 :         Append     *appendplan = (Append *) subplan;
    2400             : 
    2401          66 :         if (subplan_index < list_length(appendplan->appendplans))
    2402          66 :             subplan = (Plan *) list_nth(appendplan->appendplans, subplan_index);
    2403             :     }
    2404         192 :     else if (IsA(subplan, Result) &&
    2405          12 :              outerPlan(subplan) != NULL &&
    2406          10 :              IsA(outerPlan(subplan), Append))
    2407             :     {
    2408          10 :         Append     *appendplan = (Append *) outerPlan(subplan);
    2409             : 
    2410          10 :         if (subplan_index < list_length(appendplan->appendplans))
    2411          10 :             subplan = (Plan *) list_nth(appendplan->appendplans, subplan_index);
    2412             :     }
    2413             : 
    2414             :     /* Now, have we got a ForeignScan on the desired rel? */
    2415         258 :     if (IsA(subplan, ForeignScan))
    2416             :     {
    2417         228 :         ForeignScan *fscan = (ForeignScan *) subplan;
    2418             : 
    2419         228 :         if (bms_is_member(rtindex, fscan->fs_base_relids))
    2420         228 :             return fscan;
    2421             :     }
    2422             : 
    2423          30 :     return NULL;
    2424             : }
    2425             : 
    2426             : /*
    2427             :  * postgresPlanDirectModify
    2428             :  *      Consider a direct foreign table modification
    2429             :  *
    2430             :  * Decide whether it is safe to modify a foreign table directly, and if so,
    2431             :  * rewrite subplan accordingly.
    2432             :  */
    2433             : static bool
    2434         386 : postgresPlanDirectModify(PlannerInfo *root,
    2435             :                          ModifyTable *plan,
    2436             :                          Index resultRelation,
    2437             :                          int subplan_index)
    2438             : {
    2439         386 :     CmdType     operation = plan->operation;
    2440             :     RelOptInfo *foreignrel;
    2441             :     RangeTblEntry *rte;
    2442             :     PgFdwRelationInfo *fpinfo;
    2443             :     Relation    rel;
    2444             :     StringInfoData sql;
    2445             :     ForeignScan *fscan;
    2446         386 :     List       *processed_tlist = NIL;
    2447         386 :     List       *targetAttrs = NIL;
    2448             :     List       *remote_exprs;
    2449         386 :     List       *params_list = NIL;
    2450         386 :     List       *returningList = NIL;
    2451         386 :     List       *retrieved_attrs = NIL;
    2452             : 
    2453             :     /*
    2454             :      * Decide whether it is safe to modify a foreign table directly.
    2455             :      */
    2456             : 
    2457             :     /*
    2458             :      * The table modification must be an UPDATE or DELETE.
    2459             :      */
    2460         386 :     if (operation != CMD_UPDATE && operation != CMD_DELETE)
    2461         128 :         return false;
    2462             : 
    2463             :     /*
    2464             :      * Try to locate the ForeignScan subplan that's scanning resultRelation.
    2465             :      */
    2466         258 :     fscan = find_modifytable_subplan(root, plan, resultRelation, subplan_index);
    2467         258 :     if (!fscan)
    2468          30 :         return false;
    2469             : 
    2470             :     /*
    2471             :      * It's unsafe to modify a foreign table directly if there are any quals
    2472             :      * that should be evaluated locally.
    2473             :      */
    2474         228 :     if (fscan->scan.plan.qual != NIL)
    2475          10 :         return false;
    2476             : 
    2477             :     /* Safe to fetch data about the target foreign rel */
    2478         218 :     if (fscan->scan.scanrelid == 0)
    2479             :     {
    2480          20 :         foreignrel = find_join_rel(root, fscan->fs_relids);
    2481             :         /* We should have a rel for this foreign join. */
    2482             :         Assert(foreignrel);
    2483             :     }
    2484             :     else
    2485         198 :         foreignrel = root->simple_rel_array[resultRelation];
    2486         218 :     rte = root->simple_rte_array[resultRelation];
    2487         218 :     fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
    2488             : 
    2489             :     /*
    2490             :      * It's unsafe to update a foreign table directly, if any expressions to
    2491             :      * assign to the target columns are unsafe to evaluate remotely.
    2492             :      */
    2493         218 :     if (operation == CMD_UPDATE)
    2494             :     {
    2495             :         ListCell   *lc,
    2496             :                    *lc2;
    2497             : 
    2498             :         /*
    2499             :          * The expressions of concern are the first N columns of the processed
    2500             :          * targetlist, where N is the length of the rel's update_colnos.
    2501             :          */
    2502         100 :         get_translated_update_targetlist(root, resultRelation,
    2503             :                                          &processed_tlist, &targetAttrs);
    2504         206 :         forboth(lc, processed_tlist, lc2, targetAttrs)
    2505             :         {
    2506         116 :             TargetEntry *tle = lfirst_node(TargetEntry, lc);
    2507         116 :             AttrNumber  attno = lfirst_int(lc2);
    2508             : 
    2509             :             /* update's new-value expressions shouldn't be resjunk */
    2510             :             Assert(!tle->resjunk);
    2511             : 
    2512         116 :             if (attno <= InvalidAttrNumber) /* shouldn't happen */
    2513           0 :                 elog(ERROR, "system-column update is not supported");
    2514             : 
    2515         116 :             if (!is_foreign_expr(root, foreignrel, (Expr *) tle->expr))
    2516          10 :                 return false;
    2517             :         }
    2518             :     }
    2519             : 
    2520             :     /*
    2521             :      * Ok, rewrite subplan so as to modify the foreign table directly.
    2522             :      */
    2523         208 :     initStringInfo(&sql);
    2524             : 
    2525             :     /*
    2526             :      * Core code already has some lock on each rel being planned, so we can
    2527             :      * use NoLock here.
    2528             :      */
    2529         208 :     rel = table_open(rte->relid, NoLock);
    2530             : 
    2531             :     /*
    2532             :      * Recall the qual clauses that must be evaluated remotely.  (These are
    2533             :      * bare clauses not RestrictInfos, but deparse.c's appendConditions()
    2534             :      * doesn't care.)
    2535             :      */
    2536         208 :     remote_exprs = fpinfo->final_remote_exprs;
    2537             : 
    2538             :     /*
    2539             :      * Extract the relevant RETURNING list if any.
    2540             :      */
    2541         208 :     if (plan->returningLists)
    2542             :     {
    2543          70 :         returningList = (List *) list_nth(plan->returningLists, subplan_index);
    2544             : 
    2545             :         /*
    2546             :          * When performing an UPDATE/DELETE .. RETURNING on a join directly,
    2547             :          * we fetch from the foreign server any Vars specified in RETURNING
    2548             :          * that refer not only to the target relation but to non-target
    2549             :          * relations.  So we'll deparse them into the RETURNING clause of the
    2550             :          * remote query; use a targetlist consisting of them instead, which
    2551             :          * will be adjusted to be new fdw_scan_tlist of the foreign-scan plan
    2552             :          * node below.
    2553             :          */
    2554          70 :         if (fscan->scan.scanrelid == 0)
    2555           8 :             returningList = build_remote_returning(resultRelation, rel,
    2556             :                                                    returningList);
    2557             :     }
    2558             : 
    2559             :     /*
    2560             :      * Construct the SQL command string.
    2561             :      */
    2562         208 :     switch (operation)
    2563             :     {
    2564          90 :         case CMD_UPDATE:
    2565          90 :             deparseDirectUpdateSql(&sql, root, resultRelation, rel,
    2566             :                                    foreignrel,
    2567             :                                    processed_tlist,
    2568             :                                    targetAttrs,
    2569             :                                    remote_exprs, &params_list,
    2570             :                                    returningList, &retrieved_attrs);
    2571          90 :             break;
    2572         118 :         case CMD_DELETE:
    2573         118 :             deparseDirectDeleteSql(&sql, root, resultRelation, rel,
    2574             :                                    foreignrel,
    2575             :                                    remote_exprs, &params_list,
    2576             :                                    returningList, &retrieved_attrs);
    2577         118 :             break;
    2578           0 :         default:
    2579           0 :             elog(ERROR, "unexpected operation: %d", (int) operation);
    2580             :             break;
    2581             :     }
    2582             : 
    2583             :     /*
    2584             :      * Update the operation and target relation info.
    2585             :      */
    2586         208 :     fscan->operation = operation;
    2587         208 :     fscan->resultRelation = resultRelation;
    2588             : 
    2589             :     /*
    2590             :      * Update the fdw_exprs list that will be available to the executor.
    2591             :      */
    2592         208 :     fscan->fdw_exprs = params_list;
    2593             : 
    2594             :     /*
    2595             :      * Update the fdw_private list that will be available to the executor.
    2596             :      * Items in the list must match enum FdwDirectModifyPrivateIndex, above.
    2597             :      */
    2598         208 :     fscan->fdw_private = list_make4(makeString(sql.data),
    2599             :                                     makeBoolean((retrieved_attrs != NIL)),
    2600             :                                     retrieved_attrs,
    2601             :                                     makeBoolean(plan->canSetTag));
    2602             : 
    2603             :     /*
    2604             :      * Update the foreign-join-related fields.
    2605             :      */
    2606         208 :     if (fscan->scan.scanrelid == 0)
    2607             :     {
    2608             :         /* No need for the outer subplan. */
    2609          16 :         fscan->scan.plan.lefttree = NULL;
    2610             : 
    2611             :         /* Build new fdw_scan_tlist if UPDATE/DELETE .. RETURNING. */
    2612          16 :         if (returningList)
    2613           4 :             rebuild_fdw_scan_tlist(fscan, returningList);
    2614             :     }
    2615             : 
    2616             :     /*
    2617             :      * Finally, unset the async-capable flag if it is set, as we currently
    2618             :      * don't support asynchronous execution of direct modifications.
    2619             :      */
    2620         208 :     if (fscan->scan.plan.async_capable)
    2621          16 :         fscan->scan.plan.async_capable = false;
    2622             : 
    2623         208 :     table_close(rel, NoLock);
    2624         208 :     return true;
    2625             : }
    2626             : 
    2627             : /*
    2628             :  * postgresBeginDirectModify
    2629             :  *      Prepare a direct foreign table modification
    2630             :  */
    2631             : static void
    2632         208 : postgresBeginDirectModify(ForeignScanState *node, int eflags)
    2633             : {
    2634         208 :     ForeignScan *fsplan = (ForeignScan *) node->ss.ps.plan;
    2635         208 :     EState     *estate = node->ss.ps.state;
    2636             :     PgFdwDirectModifyState *dmstate;
    2637             :     Index       rtindex;
    2638             :     Oid         userid;
    2639             :     ForeignTable *table;
    2640             :     UserMapping *user;
    2641             :     int         numParams;
    2642             : 
    2643             :     /*
    2644             :      * Do nothing in EXPLAIN (no ANALYZE) case.  node->fdw_state stays NULL.
    2645             :      */
    2646         208 :     if (eflags & EXEC_FLAG_EXPLAIN_ONLY)
    2647          64 :         return;
    2648             : 
    2649             :     /*
    2650             :      * We'll save private state in node->fdw_state.
    2651             :      */
    2652         144 :     dmstate = (PgFdwDirectModifyState *) palloc0(sizeof(PgFdwDirectModifyState));
    2653         144 :     node->fdw_state = (void *) dmstate;
    2654             : 
    2655             :     /*
    2656             :      * Identify which user to do the remote access as.  This should match what
    2657             :      * ExecCheckPermissions() does.
    2658             :      */
    2659         144 :     userid = OidIsValid(fsplan->checkAsUser) ? fsplan->checkAsUser : GetUserId();
    2660             : 
    2661             :     /* Get info about foreign table. */
    2662         144 :     rtindex = node->resultRelInfo->ri_RangeTableIndex;
    2663         144 :     if (fsplan->scan.scanrelid == 0)
    2664           8 :         dmstate->rel = ExecOpenScanRelation(estate, rtindex, eflags);
    2665             :     else
    2666         136 :         dmstate->rel = node->ss.ss_currentRelation;
    2667         144 :     table = GetForeignTable(RelationGetRelid(dmstate->rel));
    2668         144 :     user = GetUserMapping(userid, table->serverid);
    2669             : 
    2670             :     /*
    2671             :      * Get connection to the foreign server.  Connection manager will
    2672             :      * establish new connection if necessary.
    2673             :      */
    2674         144 :     dmstate->conn = GetConnection(user, false, &dmstate->conn_state);
    2675             : 
    2676             :     /* Update the foreign-join-related fields. */
    2677         144 :     if (fsplan->scan.scanrelid == 0)
    2678             :     {
    2679             :         /* Save info about foreign table. */
    2680           8 :         dmstate->resultRel = dmstate->rel;
    2681             : 
    2682             :         /*
    2683             :          * Set dmstate->rel to NULL to teach get_returning_data() and
    2684             :          * make_tuple_from_result_row() that columns fetched from the remote
    2685             :          * server are described by fdw_scan_tlist of the foreign-scan plan
    2686             :          * node, not the tuple descriptor for the target relation.
    2687             :          */
    2688           8 :         dmstate->rel = NULL;
    2689             :     }
    2690             : 
    2691             :     /* Initialize state variable */
    2692         144 :     dmstate->num_tuples = -1;    /* -1 means not set yet */
    2693             : 
    2694             :     /* Get private info created by planner functions. */
    2695         144 :     dmstate->query = strVal(list_nth(fsplan->fdw_private,
    2696             :                                      FdwDirectModifyPrivateUpdateSql));
    2697         144 :     dmstate->has_returning = boolVal(list_nth(fsplan->fdw_private,
    2698             :                                               FdwDirectModifyPrivateHasReturning));
    2699         144 :     dmstate->retrieved_attrs = (List *) list_nth(fsplan->fdw_private,
    2700             :                                                  FdwDirectModifyPrivateRetrievedAttrs);
    2701         144 :     dmstate->set_processed = boolVal(list_nth(fsplan->fdw_private,
    2702             :                                               FdwDirectModifyPrivateSetProcessed));
    2703             : 
    2704             :     /* Create context for per-tuple temp workspace. */
    2705         144 :     dmstate->temp_cxt = AllocSetContextCreate(estate->es_query_cxt,
    2706             :                                               "postgres_fdw temporary data",
    2707             :                                               ALLOCSET_SMALL_SIZES);
    2708             : 
    2709             :     /* Prepare for input conversion of RETURNING results. */
    2710         144 :     if (dmstate->has_returning)
    2711             :     {
    2712             :         TupleDesc   tupdesc;
    2713             : 
    2714          32 :         if (fsplan->scan.scanrelid == 0)
    2715           2 :             tupdesc = get_tupdesc_for_join_scan_tuples(node);
    2716             :         else
    2717          30 :             tupdesc = RelationGetDescr(dmstate->rel);
    2718             : 
    2719          32 :         dmstate->attinmeta = TupleDescGetAttInMetadata(tupdesc);
    2720             : 
    2721             :         /*
    2722             :          * When performing an UPDATE/DELETE .. RETURNING on a join directly,
    2723             :          * initialize a filter to extract an updated/deleted tuple from a scan
    2724             :          * tuple.
    2725             :          */
    2726          32 :         if (fsplan->scan.scanrelid == 0)
    2727           2 :             init_returning_filter(dmstate, fsplan->fdw_scan_tlist, rtindex);
    2728             :     }
    2729             : 
    2730             :     /*
    2731             :      * Prepare for processing of parameters used in remote query, if any.
    2732             :      */
    2733         144 :     numParams = list_length(fsplan->fdw_exprs);
    2734         144 :     dmstate->numParams = numParams;
    2735         144 :     if (numParams > 0)
    2736           0 :         prepare_query_params((PlanState *) node,
    2737             :                              fsplan->fdw_exprs,
    2738             :                              numParams,
    2739             :                              &dmstate->param_flinfo,
    2740             :                              &dmstate->param_exprs,
    2741             :                              &dmstate->param_values);
    2742             : }
    2743             : 
    2744             : /*
    2745             :  * postgresIterateDirectModify
    2746             :  *      Execute a direct foreign table modification
    2747             :  */
    2748             : static TupleTableSlot *
    2749         836 : postgresIterateDirectModify(ForeignScanState *node)
    2750             : {
    2751         836 :     PgFdwDirectModifyState *dmstate = (PgFdwDirectModifyState *) node->fdw_state;
    2752         836 :     EState     *estate = node->ss.ps.state;
    2753         836 :     ResultRelInfo *resultRelInfo = node->resultRelInfo;
    2754             : 
    2755             :     /*
    2756             :      * If this is the first call after Begin, execute the statement.
    2757             :      */
    2758         836 :     if (dmstate->num_tuples == -1)
    2759         142 :         execute_dml_stmt(node);
    2760             : 
    2761             :     /*
    2762             :      * If the local query doesn't specify RETURNING, just clear tuple slot.
    2763             :      */
    2764         828 :     if (!resultRelInfo->ri_projectReturning)
    2765             :     {
    2766         100 :         TupleTableSlot *slot = node->ss.ss_ScanTupleSlot;
    2767         100 :         Instrumentation *instr = node->ss.ps.instrument;
    2768             : 
    2769             :         Assert(!dmstate->has_returning);
    2770             : 
    2771             :         /* Increment the command es_processed count if necessary. */
    2772         100 :         if (dmstate->set_processed)
    2773         100 :             estate->es_processed += dmstate->num_tuples;
    2774             : 
    2775             :         /* Increment the tuple count for EXPLAIN ANALYZE if necessary. */
    2776         100 :         if (instr)
    2777           0 :             instr->tuplecount += dmstate->num_tuples;
    2778             : 
    2779         100 :         return ExecClearTuple(slot);
    2780             :     }
    2781             : 
    2782             :     /*
    2783             :      * Get the next RETURNING tuple.
    2784             :      */
    2785         728 :     return get_returning_data(node);
    2786             : }
    2787             : 
    2788             : /*
    2789             :  * postgresEndDirectModify
    2790             :  *      Finish a direct foreign table modification
    2791             :  */
    2792             : static void
    2793         192 : postgresEndDirectModify(ForeignScanState *node)
    2794             : {
    2795         192 :     PgFdwDirectModifyState *dmstate = (PgFdwDirectModifyState *) node->fdw_state;
    2796             : 
    2797             :     /* if dmstate is NULL, we are in EXPLAIN; nothing to do */
    2798         192 :     if (dmstate == NULL)
    2799          64 :         return;
    2800             : 
    2801             :     /* Release PGresult */
    2802         128 :     PQclear(dmstate->result);
    2803             : 
    2804             :     /* Release remote connection */
    2805         128 :     ReleaseConnection(dmstate->conn);
    2806         128 :     dmstate->conn = NULL;
    2807             : 
    2808             :     /* MemoryContext will be deleted automatically. */
    2809             : }
    2810             : 
    2811             : /*
    2812             :  * postgresExplainForeignScan
    2813             :  *      Produce extra output for EXPLAIN of a ForeignScan on a foreign table
    2814             :  */
    2815             : static void
    2816         744 : postgresExplainForeignScan(ForeignScanState *node, ExplainState *es)
    2817             : {
    2818         744 :     ForeignScan *plan = castNode(ForeignScan, node->ss.ps.plan);
    2819         744 :     List       *fdw_private = plan->fdw_private;
    2820             : 
    2821             :     /*
    2822             :      * Identify foreign scans that are really joins or upper relations.  The
    2823             :      * input looks something like "(1) LEFT JOIN (2)", and we must replace the
    2824             :      * digit string(s), which are RT indexes, with the correct relation names.
    2825             :      * We do that here, not when the plan is created, because we can't know
    2826             :      * what aliases ruleutils.c will assign at plan creation time.
    2827             :      */
    2828         744 :     if (list_length(fdw_private) > FdwScanPrivateRelations)
    2829             :     {
    2830             :         StringInfo  relations;
    2831             :         char       *rawrelations;
    2832             :         char       *ptr;
    2833             :         int         minrti,
    2834             :                     rtoffset;
    2835             : 
    2836         234 :         rawrelations = strVal(list_nth(fdw_private, FdwScanPrivateRelations));
    2837             : 
    2838             :         /*
    2839             :          * A difficulty with using a string representation of RT indexes is
    2840             :          * that setrefs.c won't update the string when flattening the
    2841             :          * rangetable.  To find out what rtoffset was applied, identify the
    2842             :          * minimum RT index appearing in the string and compare it to the
    2843             :          * minimum member of plan->fs_base_relids.  (We expect all the relids
    2844             :          * in the join will have been offset by the same amount; the Asserts
    2845             :          * below should catch it if that ever changes.)
    2846             :          */
    2847         234 :         minrti = INT_MAX;
    2848         234 :         ptr = rawrelations;
    2849        5476 :         while (*ptr)
    2850             :         {
    2851        5242 :             if (isdigit((unsigned char) *ptr))
    2852             :             {
    2853         456 :                 int         rti = strtol(ptr, &ptr, 10);
    2854             : 
    2855         456 :                 if (rti < minrti)
    2856         256 :                     minrti = rti;
    2857             :             }
    2858             :             else
    2859        4786 :                 ptr++;
    2860             :         }
    2861         234 :         rtoffset = bms_next_member(plan->fs_base_relids, -1) - minrti;
    2862             : 
    2863             :         /* Now we can translate the string */
    2864         234 :         relations = makeStringInfo();
    2865         234 :         ptr = rawrelations;
    2866        5476 :         while (*ptr)
    2867             :         {
    2868        5242 :             if (isdigit((unsigned char) *ptr))
    2869             :             {
    2870         456 :                 int         rti = strtol(ptr, &ptr, 10);
    2871             :                 RangeTblEntry *rte;
    2872             :                 char       *relname;
    2873             :                 char       *refname;
    2874             : 
    2875         456 :                 rti += rtoffset;
    2876             :                 Assert(bms_is_member(rti, plan->fs_base_relids));
    2877         456 :                 rte = rt_fetch(rti, es->rtable);
    2878             :                 Assert(rte->rtekind == RTE_RELATION);
    2879             :                 /* This logic should agree with explain.c's ExplainTargetRel */
    2880         456 :                 relname = get_rel_name(rte->relid);
    2881         456 :                 if (es->verbose)
    2882             :                 {
    2883             :                     char       *namespace;
    2884             : 
    2885         430 :                     namespace = get_namespace_name_or_temp(get_rel_namespace(rte->relid));
    2886         430 :                     appendStringInfo(relations, "%s.%s",
    2887             :                                      quote_identifier(namespace),
    2888             :                                      quote_identifier(relname));
    2889             :                 }
    2890             :                 else
    2891          26 :                     appendStringInfoString(relations,
    2892             :                                            quote_identifier(relname));
    2893         456 :                 refname = (char *) list_nth(es->rtable_names, rti - 1);
    2894         456 :                 if (refname == NULL)
    2895           0 :                     refname = rte->eref->aliasname;
    2896         456 :                 if (strcmp(refname, relname) != 0)
    2897         286 :                     appendStringInfo(relations, " %s",
    2898             :                                      quote_identifier(refname));
    2899             :             }
    2900             :             else
    2901        4786 :                 appendStringInfoChar(relations, *ptr++);
    2902             :         }
    2903         234 :         ExplainPropertyText("Relations", relations->data, es);
    2904             :     }
    2905             : 
    2906             :     /*
    2907             :      * Add remote query, when VERBOSE option is specified.
    2908             :      */
    2909         744 :     if (es->verbose)
    2910             :     {
    2911             :         char       *sql;
    2912             : 
    2913         672 :         sql = strVal(list_nth(fdw_private, FdwScanPrivateSelectSql));
    2914         672 :         ExplainPropertyText("Remote SQL", sql, es);
    2915             :     }
    2916         744 : }
    2917             : 
    2918             : /*
    2919             :  * postgresExplainForeignModify
    2920             :  *      Produce extra output for EXPLAIN of a ModifyTable on a foreign table
    2921             :  */
    2922             : static void
    2923          76 : postgresExplainForeignModify(ModifyTableState *mtstate,
    2924             :                              ResultRelInfo *rinfo,
    2925             :                              List *fdw_private,
    2926             :                              int subplan_index,
    2927             :                              ExplainState *es)
    2928             : {
    2929          76 :     if (es->verbose)
    2930             :     {
    2931          76 :         char       *sql = strVal(list_nth(fdw_private,
    2932             :                                           FdwModifyPrivateUpdateSql));
    2933             : 
    2934          76 :         ExplainPropertyText("Remote SQL", sql, es);
    2935             : 
    2936             :         /*
    2937             :          * For INSERT we should always have batch size >= 1, but UPDATE and
    2938             :          * DELETE don't support batching so don't show the property.
    2939             :          */
    2940          76 :         if (rinfo->ri_BatchSize > 0)
    2941          26 :             ExplainPropertyInteger("Batch Size", NULL, rinfo->ri_BatchSize, es);
    2942             :     }
    2943          76 : }
    2944             : 
    2945             : /*
    2946             :  * postgresExplainDirectModify
    2947             :  *      Produce extra output for EXPLAIN of a ForeignScan that modifies a
    2948             :  *      foreign table directly
    2949             :  */
    2950             : static void
    2951          64 : postgresExplainDirectModify(ForeignScanState *node, ExplainState *es)
    2952             : {
    2953             :     List       *fdw_private;
    2954             :     char       *sql;
    2955             : 
    2956          64 :     if (es->verbose)
    2957             :     {
    2958          64 :         fdw_private = ((ForeignScan *) node->ss.ps.plan)->fdw_private;
    2959          64 :         sql = strVal(list_nth(fdw_private, FdwDirectModifyPrivateUpdateSql));
    2960          64 :         ExplainPropertyText("Remote SQL", sql, es);
    2961             :     }
    2962          64 : }
    2963             : 
    2964             : /*
    2965             :  * postgresExecForeignTruncate
    2966             :  *      Truncate one or more foreign tables
    2967             :  */
    2968             : static void
    2969          30 : postgresExecForeignTruncate(List *rels,
    2970             :                             DropBehavior behavior,
    2971             :                             bool restart_seqs)
    2972             : {
    2973          30 :     Oid         serverid = InvalidOid;
    2974          30 :     UserMapping *user = NULL;
    2975          30 :     PGconn     *conn = NULL;
    2976             :     StringInfoData sql;
    2977             :     ListCell   *lc;
    2978          30 :     bool        server_truncatable = true;
    2979             : 
    2980             :     /*
    2981             :      * By default, all postgres_fdw foreign tables are assumed truncatable.
    2982             :      * This can be overridden by a per-server setting, which in turn can be
    2983             :      * overridden by a per-table setting.
    2984             :      */
    2985          58 :     foreach(lc, rels)
    2986             :     {
    2987          34 :         ForeignServer *server = NULL;
    2988          34 :         Relation    rel = lfirst(lc);
    2989          34 :         ForeignTable *table = GetForeignTable(RelationGetRelid(rel));
    2990             :         ListCell   *cell;
    2991             :         bool        truncatable;
    2992             : 
    2993             :         /*
    2994             :          * First time through, determine whether the foreign server allows
    2995             :          * truncates. Since all specified foreign tables are assumed to belong
    2996             :          * to the same foreign server, this result can be used for other
    2997             :          * foreign tables.
    2998             :          */
    2999          34 :         if (!OidIsValid(serverid))
    3000             :         {
    3001          30 :             serverid = table->serverid;
    3002          30 :             server = GetForeignServer(serverid);
    3003             : 
    3004         120 :             foreach(cell, server->options)
    3005             :             {
    3006          96 :                 DefElem    *defel = (DefElem *) lfirst(cell);
    3007             : 
    3008          96 :                 if (strcmp(defel->defname, "truncatable") == 0)
    3009             :                 {
    3010           6 :                     server_truncatable = defGetBoolean(defel);
    3011           6 :                     break;
    3012             :                 }
    3013             :             }
    3014             :         }
    3015             : 
    3016             :         /*
    3017             :          * Confirm that all specified foreign tables belong to the same
    3018             :          * foreign server.
    3019             :          */
    3020             :         Assert(table->serverid == serverid);
    3021             : 
    3022             :         /* Determine whether this foreign table allows truncations */
    3023          34 :         truncatable = server_truncatable;
    3024          68 :         foreach(cell, table->options)
    3025             :         {
    3026          48 :             DefElem    *defel = (DefElem *) lfirst(cell);
    3027             : 
    3028          48 :             if (strcmp(defel->defname, "truncatable") == 0)
    3029             :             {
    3030          14 :                 truncatable = defGetBoolean(defel);
    3031          14 :                 break;
    3032             :             }
    3033             :         }
    3034             : 
    3035          34 :         if (!truncatable)
    3036           6 :             ereport(ERROR,
    3037             :                     (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
    3038             :                      errmsg("foreign table \"%s\" does not allow truncates",
    3039             :                             RelationGetRelationName(rel))));
    3040             :     }
    3041             :     Assert(OidIsValid(serverid));
    3042             : 
    3043             :     /*
    3044             :      * Get connection to the foreign server.  Connection manager will
    3045             :      * establish new connection if necessary.
    3046             :      */
    3047          24 :     user = GetUserMapping(GetUserId(), serverid);
    3048          24 :     conn = GetConnection(user, false, NULL);
    3049             : 
    3050             :     /* Construct the TRUNCATE command string */
    3051          24 :     initStringInfo(&sql);
    3052          24 :     deparseTruncateSql(&sql, rels, behavior, restart_seqs);
    3053             : 
    3054             :     /* Issue the TRUNCATE command to remote server */
    3055          24 :     do_sql_command(conn, sql.data);
    3056             : 
    3057          22 :     pfree(sql.data);
    3058          22 : }
    3059             : 
    3060             : /*
    3061             :  * estimate_path_cost_size
    3062             :  *      Get cost and size estimates for a foreign scan on given foreign relation
    3063             :  *      either a base relation or a join between foreign relations or an upper
    3064             :  *      relation containing foreign relations.
    3065             :  *
    3066             :  * param_join_conds are the parameterization clauses with outer relations.
    3067             :  * pathkeys specify the expected sort order if any for given path being costed.
    3068             :  * fpextra specifies additional post-scan/join-processing steps such as the
    3069             :  * final sort and the LIMIT restriction.
    3070             :  *
    3071             :  * The function returns the cost and size estimates in p_rows, p_width,
    3072             :  * p_startup_cost and p_total_cost variables.
    3073             :  */
    3074             : static void
    3075        5158 : estimate_path_cost_size(PlannerInfo *root,
    3076             :                         RelOptInfo *foreignrel,
    3077             :                         List *param_join_conds,
    3078             :                         List *pathkeys,
    3079             :                         PgFdwPathExtraData *fpextra,
    3080             :                         double *p_rows, int *p_width,
    3081             :                         Cost *p_startup_cost, Cost *p_total_cost)
    3082             : {
    3083        5158 :     PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
    3084             :     double      rows;
    3085             :     double      retrieved_rows;
    3086             :     int         width;
    3087             :     Cost        startup_cost;
    3088             :     Cost        total_cost;
    3089             : 
    3090             :     /* Make sure the core code has set up the relation's reltarget */
    3091             :     Assert(foreignrel->reltarget);
    3092             : 
    3093             :     /*
    3094             :      * If the table or the server is configured to use remote estimates,
    3095             :      * connect to the foreign server and execute EXPLAIN to estimate the
    3096             :      * number of rows selected by the restriction+join clauses.  Otherwise,
    3097             :      * estimate rows using whatever statistics we have locally, in a way
    3098             :      * similar to ordinary tables.
    3099             :      */
    3100        5158 :     if (fpinfo->use_remote_estimate)
    3101             :     {
    3102             :         List       *remote_param_join_conds;
    3103             :         List       *local_param_join_conds;
    3104             :         StringInfoData sql;
    3105             :         PGconn     *conn;
    3106             :         Selectivity local_sel;
    3107             :         QualCost    local_cost;
    3108        2490 :         List       *fdw_scan_tlist = NIL;
    3109             :         List       *remote_conds;
    3110             : 
    3111             :         /* Required only to be passed to deparseSelectStmtForRel */
    3112             :         List       *retrieved_attrs;
    3113             : 
    3114             :         /*
    3115             :          * param_join_conds might contain both clauses that are safe to send
    3116             :          * across, and clauses that aren't.
    3117             :          */
    3118        2490 :         classifyConditions(root, foreignrel, param_join_conds,
    3119             :                            &remote_param_join_conds, &local_param_join_conds);
    3120             : 
    3121             :         /* Build the list of columns to be fetched from the foreign server. */
    3122        2490 :         if (IS_JOIN_REL(foreignrel) || IS_UPPER_REL(foreignrel))
    3123        1012 :             fdw_scan_tlist = build_tlist_to_deparse(foreignrel);
    3124             :         else
    3125        1478 :             fdw_scan_tlist = NIL;
    3126             : 
    3127             :         /*
    3128             :          * The complete list of remote conditions includes everything from
    3129             :          * baserestrictinfo plus any extra join_conds relevant to this
    3130             :          * particular path.
    3131             :          */
    3132        2490 :         remote_conds = list_concat(remote_param_join_conds,
    3133        2490 :                                    fpinfo->remote_conds);
    3134             : 
    3135             :         /*
    3136             :          * Construct EXPLAIN query including the desired SELECT, FROM, and
    3137             :          * WHERE clauses. Params and other-relation Vars are replaced by dummy
    3138             :          * values, so don't request params_list.
    3139             :          */
    3140        2490 :         initStringInfo(&sql);
    3141        2490 :         appendStringInfoString(&sql, "EXPLAIN ");
    3142        2490 :         deparseSelectStmtForRel(&sql, root, foreignrel, fdw_scan_tlist,
    3143             :                                 remote_conds, pathkeys,
    3144        2490 :                                 fpextra ? fpextra->has_final_sort : false,
    3145        2490 :                                 fpextra ? fpextra->has_limit : false,
    3146             :                                 false, &retrieved_attrs, NULL);
    3147             : 
    3148             :         /* Get the remote estimate */
    3149        2490 :         conn = GetConnection(fpinfo->user, false, NULL);
    3150        2490 :         get_remote_estimate(sql.data, conn, &rows, &width,
    3151             :                             &startup_cost, &total_cost);
    3152        2488 :         ReleaseConnection(conn);
    3153             : 
    3154        2488 :         retrieved_rows = rows;
    3155             : 
    3156             :         /* Factor in the selectivity of the locally-checked quals */
    3157        2488 :         local_sel = clauselist_selectivity(root,
    3158             :                                            local_param_join_conds,
    3159        2488 :                                            foreignrel->relid,
    3160             :                                            JOIN_INNER,
    3161             :                                            NULL);
    3162        2488 :         local_sel *= fpinfo->local_conds_sel;
    3163             : 
    3164        2488 :         rows = clamp_row_est(rows * local_sel);
    3165             : 
    3166             :         /* Add in the eval cost of the locally-checked quals */
    3167        2488 :         startup_cost += fpinfo->local_conds_cost.startup;
    3168        2488 :         total_cost += fpinfo->local_conds_cost.per_tuple * retrieved_rows;
    3169        2488 :         cost_qual_eval(&local_cost, local_param_join_conds, root);
    3170        2488 :         startup_cost += local_cost.startup;
    3171        2488 :         total_cost += local_cost.per_tuple * retrieved_rows;
    3172             : 
    3173             :         /*
    3174             :          * Add in tlist eval cost for each output row.  In case of an
    3175             :          * aggregate, some of the tlist expressions such as grouping
    3176             :          * expressions will be evaluated remotely, so adjust the costs.
    3177             :          */
    3178        2488 :         startup_cost += foreignrel->reltarget->cost.startup;
    3179        2488 :         total_cost += foreignrel->reltarget->cost.startup;
    3180        2488 :         total_cost += foreignrel->reltarget->cost.per_tuple * rows;
    3181        2488 :         if (IS_UPPER_REL(foreignrel))
    3182             :         {
    3183             :             QualCost    tlist_cost;
    3184             : 
    3185          80 :             cost_qual_eval(&tlist_cost, fdw_scan_tlist, root);
    3186          80 :             startup_cost -= tlist_cost.startup;
    3187          80 :             total_cost -= tlist_cost.startup;
    3188          80 :             total_cost -= tlist_cost.per_tuple * rows;
    3189             :         }
    3190             :     }
    3191             :     else
    3192             :     {
    3193        2668 :         Cost        run_cost = 0;
    3194             : 
    3195             :         /*
    3196             :          * We don't support join conditions in this mode (hence, no
    3197             :          * parameterized paths can be made).
    3198             :          */
    3199             :         Assert(param_join_conds == NIL);
    3200             : 
    3201             :         /*
    3202             :          * We will come here again and again with different set of pathkeys or
    3203             :          * additional post-scan/join-processing steps that caller wants to
    3204             :          * cost.  We don't need to calculate the cost/size estimates for the
    3205             :          * underlying scan, join, or grouping each time.  Instead, use those
    3206             :          * estimates if we have cached them already.
    3207             :          */
    3208        2668 :         if (fpinfo->rel_startup_cost >= 0 && fpinfo->rel_total_cost >= 0)
    3209             :         {
    3210             :             Assert(fpinfo->retrieved_rows >= 0);
    3211             : 
    3212         618 :             rows = fpinfo->rows;
    3213         618 :             retrieved_rows = fpinfo->retrieved_rows;
    3214         618 :             width = fpinfo->width;
    3215         618 :             startup_cost = fpinfo->rel_startup_cost;
    3216         618 :             run_cost = fpinfo->rel_total_cost - fpinfo->rel_startup_cost;
    3217             : 
    3218             :             /*
    3219             :              * If we estimate the costs of a foreign scan or a foreign join
    3220             :              * with additional post-scan/join-processing steps, the scan or
    3221             :              * join costs obtained from the cache wouldn't yet contain the
    3222             :              * eval costs for the final scan/join target, which would've been
    3223             :              * updated by apply_scanjoin_target_to_paths(); add the eval costs
    3224             :              * now.
    3225             :              */
    3226         618 :             if (fpextra && !IS_UPPER_REL(foreignrel))
    3227             :             {
    3228             :                 /* Shouldn't get here unless we have LIMIT */
    3229             :                 Assert(fpextra->has_limit);
    3230             :                 Assert(foreignrel->reloptkind == RELOPT_BASEREL ||
    3231             :                        foreignrel->reloptkind == RELOPT_JOINREL);
    3232         178 :                 startup_cost += foreignrel->reltarget->cost.startup;
    3233         178 :                 run_cost += foreignrel->reltarget->cost.per_tuple * rows;
    3234             :             }
    3235             :         }
    3236        2050 :         else if (IS_JOIN_REL(foreignrel))
    3237         176 :         {
    3238             :             PgFdwRelationInfo *fpinfo_i;
    3239             :             PgFdwRelationInfo *fpinfo_o;
    3240             :             QualCost    join_cost;
    3241             :             QualCost    remote_conds_cost;
    3242             :             double      nrows;
    3243             : 
    3244             :             /* Use rows/width estimates made by the core code. */
    3245         176 :             rows = foreignrel->rows;
    3246         176 :             width = foreignrel->reltarget->width;
    3247             : 
    3248             :             /* For join we expect inner and outer relations set */
    3249             :             Assert(fpinfo->innerrel && fpinfo->outerrel);
    3250             : 
    3251         176 :             fpinfo_i = (PgFdwRelationInfo *) fpinfo->innerrel->fdw_private;
    3252         176 :             fpinfo_o = (PgFdwRelationInfo *) fpinfo->outerrel->fdw_private;
    3253             : 
    3254             :             /* Estimate of number of rows in cross product */
    3255         176 :             nrows = fpinfo_i->rows * fpinfo_o->rows;
    3256             : 
    3257             :             /*
    3258             :              * Back into an estimate of the number of retrieved rows.  Just in
    3259             :              * case this is nuts, clamp to at most nrows.
    3260             :              */
    3261         176 :             retrieved_rows = clamp_row_est(rows / fpinfo->local_conds_sel);
    3262         176 :             retrieved_rows = Min(retrieved_rows, nrows);
    3263             : 
    3264             :             /*
    3265             :              * The cost of foreign join is estimated as cost of generating
    3266             :              * rows for the joining relations + cost for applying quals on the
    3267             :              * rows.
    3268             :              */
    3269             : 
    3270             :             /*
    3271             :              * Calculate the cost of clauses pushed down to the foreign server
    3272             :              */
    3273         176 :             cost_qual_eval(&remote_conds_cost, fpinfo->remote_conds, root);
    3274             :             /* Calculate the cost of applying join clauses */
    3275         176 :             cost_qual_eval(&join_cost, fpinfo->joinclauses, root);
    3276             : 
    3277             :             /*
    3278             :              * Startup cost includes startup cost of joining relations and the
    3279             :              * startup cost for join and other clauses. We do not include the
    3280             :              * startup cost specific to join strategy (e.g. setting up hash
    3281             :              * tables) since we do not know what strategy the foreign server
    3282             :              * is going to use.
    3283             :              */
    3284         176 :             startup_cost = fpinfo_i->rel_startup_cost + fpinfo_o->rel_startup_cost;
    3285         176 :             startup_cost += join_cost.startup;
    3286         176 :             startup_cost += remote_conds_cost.startup;
    3287         176 :             startup_cost += fpinfo->local_conds_cost.startup;
    3288             : 
    3289             :             /*
    3290             :              * Run time cost includes:
    3291             :              *
    3292             :              * 1. Run time cost (total_cost - startup_cost) of relations being
    3293             :              * joined
    3294             :              *
    3295             :              * 2. Run time cost of applying join clauses on the cross product
    3296             :              * of the joining relations.
    3297             :              *
    3298             :              * 3. Run time cost of applying pushed down other clauses on the
    3299             :              * result of join
    3300             :              *
    3301             :              * 4. Run time cost of applying nonpushable other clauses locally
    3302             :              * on the result fetched from the foreign server.
    3303             :              */
    3304         176 :             run_cost = fpinfo_i->rel_total_cost - fpinfo_i->rel_startup_cost;
    3305         176 :             run_cost += fpinfo_o->rel_total_cost - fpinfo_o->rel_startup_cost;
    3306         176 :             run_cost += nrows * join_cost.per_tuple;
    3307         176 :             nrows = clamp_row_est(nrows * fpinfo->joinclause_sel);
    3308         176 :             run_cost += nrows * remote_conds_cost.per_tuple;
    3309         176 :             run_cost += fpinfo->local_conds_cost.per_tuple * retrieved_rows;
    3310             : 
    3311             :             /* Add in tlist eval cost for each output row */
    3312         176 :             startup_cost += foreignrel->reltarget->cost.startup;
    3313         176 :             run_cost += foreignrel->reltarget->cost.per_tuple * rows;
    3314             :         }
    3315        1874 :         else if (IS_UPPER_REL(foreignrel))
    3316         186 :         {
    3317         186 :             RelOptInfo *outerrel = fpinfo->outerrel;
    3318             :             PgFdwRelationInfo *ofpinfo;
    3319             :             AggClauseCosts aggcosts;
    3320             :             double      input_rows;
    3321             :             int         numGroupCols;
    3322         186 :             double      numGroups = 1;
    3323             : 
    3324             :             /* The upper relation should have its outer relation set */
    3325             :             Assert(outerrel);
    3326             :             /* and that outer relation should have its reltarget set */
    3327             :             Assert(outerrel->reltarget);
    3328             : 
    3329             :             /*
    3330             :              * This cost model is mixture of costing done for sorted and
    3331             :              * hashed aggregates in cost_agg().  We are not sure which
    3332             :              * strategy will be considered at remote side, thus for
    3333             :              * simplicity, we put all startup related costs in startup_cost
    3334             :              * and all finalization and run cost are added in total_cost.
    3335             :              */
    3336             : 
    3337         186 :             ofpinfo = (PgFdwRelationInfo *) outerrel->fdw_private;
    3338             : 
    3339             :             /* Get rows from input rel */
    3340         186 :             input_rows = ofpinfo->rows;
    3341             : 
    3342             :             /* Collect statistics about aggregates for estimating costs. */
    3343        1116 :             MemSet(&aggcosts, 0, sizeof(AggClauseCosts));
    3344         186 :             if (root->parse->hasAggs)
    3345             :             {
    3346         178 :                 get_agg_clause_costs(root, AGGSPLIT_SIMPLE, &aggcosts);
    3347             :             }
    3348             : 
    3349             :             /* Get number of grouping columns and possible number of groups */
    3350         186 :             numGroupCols = list_length(root->processed_groupClause);
    3351         186 :             numGroups = estimate_num_groups(root,
    3352             :                                             get_sortgrouplist_exprs(root->processed_groupClause,
    3353             :                                                                     fpinfo->grouped_tlist),
    3354             :                                             input_rows, NULL, NULL);
    3355             : 
    3356             :             /*
    3357             :              * Get the retrieved_rows and rows estimates.  If there are HAVING
    3358             :              * quals, account for their selectivity.
    3359             :              */
    3360         186 :             if (root->hasHavingQual)
    3361             :             {
    3362             :                 /* Factor in the selectivity of the remotely-checked quals */
    3363             :                 retrieved_rows =
    3364          28 :                     clamp_row_est(numGroups *
    3365          28 :                                   clauselist_selectivity(root,
    3366             :                                                          fpinfo->remote_conds,
    3367             :                                                          0,
    3368             :                                                          JOIN_INNER,
    3369             :                                                          NULL));
    3370             :                 /* Factor in the selectivity of the locally-checked quals */
    3371          28 :                 rows = clamp_row_est(retrieved_rows * fpinfo->local_conds_sel);
    3372             :             }
    3373             :             else
    3374             :             {
    3375         158 :                 rows = retrieved_rows = numGroups;
    3376             :             }
    3377             : 
    3378             :             /* Use width estimate made by the core code. */
    3379         186 :             width = foreignrel->reltarget->width;
    3380             : 
    3381             :             /*-----
    3382             :              * Startup cost includes:
    3383             :              *    1. Startup cost for underneath input relation, adjusted for
    3384             :              *       tlist replacement by apply_scanjoin_target_to_paths()
    3385             :              *    2. Cost of performing aggregation, per cost_agg()
    3386             :              *-----
    3387             :              */
    3388         186 :             startup_cost = ofpinfo->rel_startup_cost;
    3389         186 :             startup_cost += outerrel->reltarget->cost.startup;
    3390         186 :             startup_cost += aggcosts.transCost.startup;
    3391         186 :             startup_cost += aggcosts.transCost.per_tuple * input_rows;
    3392         186 :             startup_cost += aggcosts.finalCost.startup;
    3393         186 :             startup_cost += (cpu_operator_cost * numGroupCols) * input_rows;
    3394             : 
    3395             :             /*-----
    3396             :              * Run time cost includes:
    3397             :              *    1. Run time cost of underneath input relation, adjusted for
    3398             :              *       tlist replacement by apply_scanjoin_target_to_paths()
    3399             :              *    2. Run time cost of performing aggregation, per cost_agg()
    3400             :              *-----
    3401             :              */
    3402         186 :             run_cost = ofpinfo->rel_total_cost - ofpinfo->rel_startup_cost;
    3403         186 :             run_cost += outerrel->reltarget->cost.per_tuple * input_rows;
    3404         186 :             run_cost += aggcosts.finalCost.per_tuple * numGroups;
    3405         186 :             run_cost += cpu_tuple_cost * numGroups;
    3406             : 
    3407             :             /* Account for the eval cost of HAVING quals, if any */
    3408         186 :             if (root->hasHavingQual)
    3409             :             {
    3410             :                 QualCost    remote_cost;
    3411             : 
    3412             :                 /* Add in the eval cost of the remotely-checked quals */
    3413          28 :                 cost_qual_eval(&remote_cost, fpinfo->remote_conds, root);
    3414          28 :                 startup_cost += remote_cost.startup;
    3415          28 :                 run_cost += remote_cost.per_tuple * numGroups;
    3416             :                 /* Add in the eval cost of the locally-checked quals */
    3417          28 :                 startup_cost += fpinfo->local_conds_cost.startup;
    3418          28 :                 run_cost += fpinfo->local_conds_cost.per_tuple * retrieved_rows;
    3419             :             }
    3420             : 
    3421             :             /* Add in tlist eval cost for each output row */
    3422         186 :             startup_cost += foreignrel->reltarget->cost.startup;
    3423         186 :             run_cost += foreignrel->reltarget->cost.per_tuple * rows;
    3424             :         }
    3425             :         else
    3426             :         {
    3427             :             Cost        cpu_per_tuple;
    3428             : 
    3429             :             /* Use rows/width estimates made by set_baserel_size_estimates. */
    3430        1688 :             rows = foreignrel->rows;
    3431        1688 :             width = foreignrel->reltarget->width;
    3432             : 
    3433             :             /*
    3434             :              * Back into an estimate of the number of retrieved rows.  Just in
    3435             :              * case this is nuts, clamp to at most foreignrel->tuples.
    3436             :              */
    3437        1688 :             retrieved_rows = clamp_row_est(rows / fpinfo->local_conds_sel);
    3438        1688 :             retrieved_rows = Min(retrieved_rows, foreignrel->tuples);
    3439             : 
    3440             :             /*
    3441             :              * Cost as though this were a seqscan, which is pessimistic.  We
    3442             :              * effectively imagine the local_conds are being evaluated
    3443             :              * remotely, too.
    3444             :              */
    3445        1688 :             startup_cost = 0;
    3446        1688 :             run_cost = 0;
    3447        1688 :             run_cost += seq_page_cost * foreignrel->pages;
    3448             : 
    3449        1688 :             startup_cost += foreignrel->baserestrictcost.startup;
    3450        1688 :             cpu_per_tuple = cpu_tuple_cost + foreignrel->baserestrictcost.per_tuple;
    3451        1688 :             run_cost += cpu_per_tuple * foreignrel->tuples;
    3452             : 
    3453             :             /* Add in tlist eval cost for each output row */
    3454        1688 :             startup_cost += foreignrel->reltarget->cost.startup;
    3455        1688 :             run_cost += foreignrel->reltarget->cost.per_tuple * rows;
    3456             :         }
    3457             : 
    3458             :         /*
    3459             :          * Without remote estimates, we have no real way to estimate the cost
    3460             :          * of generating sorted output.  It could be free if the query plan
    3461             :          * the remote side would have chosen generates properly-sorted output
    3462             :          * anyway, but in most cases it will cost something.  Estimate a value
    3463             :          * high enough that we won't pick the sorted path when the ordering
    3464             :          * isn't locally useful, but low enough that we'll err on the side of
    3465             :          * pushing down the ORDER BY clause when it's useful to do so.
    3466             :          */
    3467        2668 :         if (pathkeys != NIL)
    3468             :         {
    3469         508 :             if (IS_UPPER_REL(foreignrel))
    3470             :             {
    3471             :                 Assert(foreignrel->reloptkind == RELOPT_UPPER_REL &&
    3472             :                        fpinfo->stage == UPPERREL_GROUP_AGG);
    3473          60 :                 adjust_foreign_grouping_path_cost(root, pathkeys,
    3474             :                                                   retrieved_rows, width,
    3475             :                                                   fpextra->limit_tuples,
    3476             :                                                   &startup_cost, &run_cost);
    3477             :             }
    3478             :             else
    3479             :             {
    3480         448 :                 startup_cost *= DEFAULT_FDW_SORT_MULTIPLIER;
    3481         448 :                 run_cost *= DEFAULT_FDW_SORT_MULTIPLIER;
    3482             :             }
    3483             :         }
    3484             : 
    3485        2668 :         total_cost = startup_cost + run_cost;
    3486             : 
    3487             :         /* Adjust the cost estimates if we have LIMIT */
    3488        2668 :         if (fpextra && fpextra->has_limit)
    3489             :         {
    3490         182 :             adjust_limit_rows_costs(&rows, &startup_cost, &total_cost,
    3491             :                                     fpextra->offset_est, fpextra->count_est);
    3492         182 :             retrieved_rows = rows;
    3493             :         }
    3494             :     }
    3495             : 
    3496             :     /*
    3497             :      * If this includes the final sort step, the given target, which will be
    3498             :      * applied to the resulting path, might have different expressions from
    3499             :      * the foreignrel's reltarget (see make_sort_input_target()); adjust tlist
    3500             :      * eval costs.
    3501             :      */
    3502        5156 :     if (fpextra && fpextra->has_final_sort &&
    3503         214 :         fpextra->target != foreignrel->reltarget)
    3504             :     {
    3505          12 :         QualCost    oldcost = foreignrel->reltarget->cost;
    3506          12 :         QualCost    newcost = fpextra->target->cost;
    3507             : 
    3508          12 :         startup_cost += newcost.startup - oldcost.startup;
    3509          12 :         total_cost += newcost.startup - oldcost.startup;
    3510          12 :         total_cost += (newcost.per_tuple - oldcost.per_tuple) * rows;
    3511             :     }
    3512             : 
    3513             :     /*
    3514             :      * Cache the retrieved rows and cost estimates for scans, joins, or
    3515             :      * groupings without any parameterization, pathkeys, or additional
    3516             :      * post-scan/join-processing steps, before adding the costs for
    3517             :      * transferring data from the foreign server.  These estimates are useful
    3518             :      * for costing remote joins involving this relation or costing other
    3519             :      * remote operations on this relation such as remote sorts and remote
    3520             :      * LIMIT restrictions, when the costs can not be obtained from the foreign
    3521             :      * server.  This function will be called at least once for every foreign
    3522             :      * relation without any parameterization, pathkeys, or additional
    3523             :      * post-scan/join-processing steps.
    3524             :      */
    3525        5156 :     if (pathkeys == NIL && param_join_conds == NIL && fpextra == NULL)
    3526             :     {
    3527        3132 :         fpinfo->retrieved_rows = retrieved_rows;
    3528        3132 :         fpinfo->rel_startup_cost = startup_cost;
    3529        3132 :         fpinfo->rel_total_cost = total_cost;
    3530             :     }
    3531             : 
    3532             :     /*
    3533             :      * Add some additional cost factors to account for connection overhead
    3534             :      * (fdw_startup_cost), transferring data across the network
    3535             :      * (fdw_tuple_cost per retrieved row), and local manipulation of the data
    3536             :      * (cpu_tuple_cost per retrieved row).
    3537             :      */
    3538        5156 :     startup_cost += fpinfo->fdw_startup_cost;
    3539        5156 :     total_cost += fpinfo->fdw_startup_cost;
    3540        5156 :     total_cost += fpinfo->fdw_tuple_cost * retrieved_rows;
    3541        5156 :     total_cost += cpu_tuple_cost * retrieved_rows;
    3542             : 
    3543             :     /*
    3544             :      * If we have LIMIT, we should prefer performing the restriction remotely
    3545             :      * rather than locally, as the former avoids extra row fetches from the
    3546             :      * remote that the latter might cause.  But since the core code doesn't
    3547             :      * account for such fetches when estimating the costs of the local
    3548             :      * restriction (see create_limit_path()), there would be no difference
    3549             :      * between the costs of the local restriction and the costs of the remote
    3550             :      * restriction estimated above if we don't use remote estimates (except
    3551             :      * for the case where the foreignrel is a grouping relation, the given
    3552             :      * pathkeys is not NIL, and the effects of a bounded sort for that rel is
    3553             :      * accounted for in costing the remote restriction).  Tweak the costs of
    3554             :      * the remote restriction to ensure we'll prefer it if LIMIT is a useful
    3555             :      * one.
    3556             :      */
    3557        5156 :     if (!fpinfo->use_remote_estimate &&
    3558         242 :         fpextra && fpextra->has_limit &&
    3559         182 :         fpextra->limit_tuples > 0 &&
    3560         182 :         fpextra->limit_tuples < fpinfo->rows)
    3561             :     {
    3562             :         Assert(fpinfo->rows > 0);
    3563         170 :         total_cost -= (total_cost - startup_cost) * 0.05 *
    3564         170 :             (fpinfo->rows - fpextra->limit_tuples) / fpinfo->rows;
    3565             :     }
    3566             : 
    3567             :     /* Return results. */
    3568        5156 :     *p_rows = rows;
    3569        5156 :     *p_width = width;
    3570        5156 :     *p_startup_cost = startup_cost;
    3571        5156 :     *p_total_cost = total_cost;
    3572        5156 : }
    3573             : 
    3574             : /*
    3575             :  * Estimate costs of executing a SQL statement remotely.
    3576             :  * The given "sql" must be an EXPLAIN command.
    3577             :  */
    3578             : static void
    3579        2490 : get_remote_estimate(const char *sql, PGconn *conn,
    3580             :                     double *rows, int *width,
    3581             :                     Cost *startup_cost, Cost *total_cost)
    3582             : {
    3583        2490 :     PGresult   *volatile res = NULL;
    3584             : 
    3585             :     /* PGresult must be released before leaving this function. */
    3586        2490 :     PG_TRY();
    3587             :     {
    3588             :         char       *line;
    3589             :         char       *p;
    3590             :         int         n;
    3591             : 
    3592             :         /*
    3593             :          * Execute EXPLAIN remotely.
    3594             :          */
    3595        2490 :         res = pgfdw_exec_query(conn, sql, NULL);
    3596        2488 :         if (PQresultStatus(res) != PGRES_TUPLES_OK)
    3597           0 :             pgfdw_report_error(ERROR, res, conn, false, sql);
    3598             : 
    3599             :         /*
    3600             :          * Extract cost numbers for topmost plan node.  Note we search for a
    3601             :          * left paren from the end of the line to avoid being confused by
    3602             :          * other uses of parentheses.
    3603             :          */
    3604        2488 :         line = PQgetvalue(res, 0, 0);
    3605        2488 :         p = strrchr(line, '(');
    3606        2488 :         if (p == NULL)
    3607           0 :             elog(ERROR, "could not interpret EXPLAIN output: \"%s\"", line);
    3608        2488 :         n = sscanf(p, "(cost=%lf..%lf rows=%lf width=%d)",
    3609             :                    startup_cost, total_cost, rows, width);
    3610        2488 :         if (n != 4)
    3611           0 :             elog(ERROR, "could not interpret EXPLAIN output: \"%s\"", line);
    3612             :     }
    3613           2 :     PG_FINALLY();
    3614             :     {
    3615        2490 :         PQclear(res);
    3616             :     }
    3617        2490 :     PG_END_TRY();
    3618        2488 : }
    3619             : 
    3620             : /*
    3621             :  * Adjust the cost estimates of a foreign grouping path to include the cost of
    3622             :  * generating properly-sorted output.
    3623             :  */
    3624             : static void
    3625          60 : adjust_foreign_grouping_path_cost(PlannerInfo *root,
    3626             :                                   List *pathkeys,
    3627             :                                   double retrieved_rows,
    3628             :                                   double width,
    3629             :                                   double limit_tuples,
    3630             :                                   Cost *p_startup_cost,
    3631             :                                   Cost *p_run_cost)
    3632             : {
    3633             :     /*
    3634             :      * If the GROUP BY clause isn't sort-able, the plan chosen by the remote
    3635             :      * side is unlikely to generate properly-sorted output, so it would need
    3636             :      * an explicit sort; adjust the given costs with cost_sort().  Likewise,
    3637             :      * if the GROUP BY clause is sort-able but isn't a superset of the given
    3638             :      * pathkeys, adjust the costs with that function.  Otherwise, adjust the
    3639             :      * costs by applying the same heuristic as for the scan or join case.
    3640             :      */
    3641          60 :     if (!grouping_is_sortable(root->processed_groupClause) ||
    3642          60 :         !pathkeys_contained_in(pathkeys, root->group_pathkeys))
    3643          44 :     {
    3644             :         Path        sort_path;  /* dummy for result of cost_sort */
    3645             : 
    3646          44 :         cost_sort(&sort_path,
    3647             :                   root,
    3648             :                   pathkeys,
    3649          44 :                   *p_startup_cost + *p_run_cost,
    3650             :                   retrieved_rows,
    3651             :                   width,
    3652             :                   0.0,
    3653             :                   work_mem,
    3654             :                   limit_tuples);
    3655             : 
    3656          44 :         *p_startup_cost = sort_path.startup_cost;
    3657          44 :         *p_run_cost = sort_path.total_cost - sort_path.startup_cost;
    3658             :     }
    3659             :     else
    3660             :     {
    3661             :         /*
    3662             :          * The default extra cost seems too large for foreign-grouping cases;
    3663             :          * add 1/4th of that default.
    3664             :          */
    3665          16 :         double      sort_multiplier = 1.0 + (DEFAULT_FDW_SORT_MULTIPLIER
    3666             :                                              - 1.0) * 0.25;
    3667             : 
    3668          16 :         *p_startup_cost *= sort_multiplier;
    3669          16 :         *p_run_cost *= sort_multiplier;
    3670             :     }
    3671          60 : }
    3672             : 
    3673             : /*
    3674             :  * Detect whether we want to process an EquivalenceClass member.
    3675             :  *
    3676             :  * This is a callback for use by generate_implied_equalities_for_column.
    3677             :  */
    3678             : static bool
    3679         596 : ec_member_matches_foreign(PlannerInfo *root, RelOptInfo *rel,
    3680             :                           EquivalenceClass *ec, EquivalenceMember *em,
    3681             :                           void *arg)
    3682             : {
    3683         596 :     ec_member_foreign_arg *state = (ec_member_foreign_arg *) arg;
    3684         596 :     Expr       *expr = em->em_expr;
    3685             : 
    3686             :     /*
    3687             :      * If we've identified what we're processing in the current scan, we only
    3688             :      * want to match that expression.
    3689             :      */
    3690         596 :     if (state->current != NULL)
    3691           0 :         return equal(expr, state->current);
    3692             : 
    3693             :     /*
    3694             :      * Otherwise, ignore anything we've already processed.
    3695             :      */
    3696         596 :     if (list_member(state->already_used, expr))
    3697         318 :         return false;
    3698             : 
    3699             :     /* This is the new target to process. */
    3700         278 :     state->current = expr;
    3701         278 :     return true;
    3702             : }
    3703             : 
    3704             : /*
    3705             :  * Create cursor for node's query with current parameter values.
    3706             :  */
    3707             : static void
    3708        1582 : create_cursor(ForeignScanState *node)
    3709             : {
    3710        1582 :     PgFdwScanState *fsstate = (PgFdwScanState *) node->fdw_state;
    3711        1582 :     ExprContext *econtext = node->ss.ps.ps_ExprContext;
    3712        1582 :     int         numParams = fsstate->numParams;
    3713        1582 :     const char **values = fsstate->param_values;
    3714        1582 :     PGconn     *conn = fsstate->conn;
    3715             :     StringInfoData buf;
    3716             :     PGresult   *res;
    3717             : 
    3718             :     /* First, process a pending asynchronous request, if any. */
    3719        1582 :     if (fsstate->conn_state->pendingAreq)
    3720           2 :         process_pending_request(fsstate->conn_state->pendingAreq);
    3721             : 
    3722             :     /*
    3723             :      * Construct array of query parameter values in text format.  We do the
    3724             :      * conversions in the short-lived per-tuple context, so as not to cause a
    3725             :      * memory leak over repeated scans.
    3726             :      */
    3727        1582 :     if (numParams > 0)
    3728             :     {
    3729             :         MemoryContext oldcontext;
    3730             : 
    3731         692 :         oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
    3732             : 
    3733         692 :         process_query_params(econtext,
    3734             :                              fsstate->param_flinfo,
    3735             :                              fsstate->param_exprs,
    3736             :                              values);
    3737             : 
    3738         692 :         MemoryContextSwitchTo(oldcontext);
    3739             :     }
    3740             : 
    3741             :     /* Construct the DECLARE CURSOR command */
    3742        1582 :     initStringInfo(&buf);
    3743        1582 :     appendStringInfo(&buf, "DECLARE c%u CURSOR FOR\n%s",
    3744             :                      fsstate->cursor_number, fsstate->query);
    3745             : 
    3746             :     /*
    3747             :      * Notice that we pass NULL for paramTypes, thus forcing the remote server
    3748             :      * to infer types for all parameters.  Since we explicitly cast every
    3749             :      * parameter (see deparse.c), the "inference" is trivial and will produce
    3750             :      * the desired result.  This allows us to avoid assuming that the remote
    3751             :      * server has the same OIDs we do for the parameters' types.
    3752             :      */
    3753        1582 :     if (!PQsendQueryParams(conn, buf.data, numParams,
    3754             :                            NULL, values, NULL, NULL, 0))
    3755           0 :         pgfdw_report_error(ERROR, NULL, conn, false, buf.data);
    3756             : 
    3757             :     /*
    3758             :      * Get the result, and check for success.
    3759             :      *
    3760             :      * We don't use a PG_TRY block here, so be careful not to throw error
    3761             :      * without releasing the PGresult.
    3762             :      */
    3763        1582 :     res = pgfdw_get_result(conn);
    3764        1582 :     if (PQresultStatus(res) != PGRES_COMMAND_OK)
    3765           6 :         pgfdw_report_error(ERROR, res, conn, true, fsstate->query);
    3766        1576 :     PQclear(res);
    3767             : 
    3768             :     /* Mark the cursor as created, and show no tuples have been retrieved */
    3769        1576 :     fsstate->cursor_exists = true;
    3770        1576 :     fsstate->tuples = NULL;
    3771        1576 :     fsstate->num_tuples = 0;
    3772        1576 :     fsstate->next_tuple = 0;
    3773        1576 :     fsstate->fetch_ct_2 = 0;
    3774        1576 :     fsstate->eof_reached = false;
    3775             : 
    3776             :     /* Clean up */
    3777        1576 :     pfree(buf.data);
    3778        1576 : }
    3779             : 
    3780             : /*
    3781             :  * Fetch some more rows from the node's cursor.
    3782             :  */
    3783             : static void
    3784        2914 : fetch_more_data(ForeignScanState *node)
    3785             : {
    3786        2914 :     PgFdwScanState *fsstate = (PgFdwScanState *) node->fdw_state;
    3787        2914 :     PGresult   *volatile res = NULL;
    3788             :     MemoryContext oldcontext;
    3789             : 
    3790             :     /*
    3791             :      * We'll store the tuples in the batch_cxt.  First, flush the previous
    3792             :      * batch.
    3793             :      */
    3794        2914 :     fsstate->tuples = NULL;
    3795        2914 :     MemoryContextReset(fsstate->batch_cxt);
    3796        2914 :     oldcontext = MemoryContextSwitchTo(fsstate->batch_cxt);
    3797             : 
    3798             :     /* PGresult must be released before leaving this function. */
    3799        2914 :     PG_TRY();
    3800             :     {
    3801        2914 :         PGconn     *conn = fsstate->conn;
    3802             :         int         numrows;
    3803             :         int         i;
    3804             : 
    3805        2914 :         if (fsstate->async_capable)
    3806             :         {
    3807             :             Assert(fsstate->conn_state->pendingAreq);
    3808             : 
    3809             :             /*
    3810             :              * The query was already sent by an earlier call to
    3811             :              * fetch_more_data_begin.  So now we just fetch the result.
    3812             :              */
    3813         316 :             res = pgfdw_get_result(conn);
    3814             :             /* On error, report the original query, not the FETCH. */
    3815         316 :             if (PQresultStatus(res) != PGRES_TUPLES_OK)
    3816           0 :                 pgfdw_report_error(ERROR, res, conn, false, fsstate->query);
    3817             : 
    3818             :             /* Reset per-connection state */
    3819         316 :             fsstate->conn_state->pendingAreq = NULL;
    3820             :         }
    3821             :         else
    3822             :         {
    3823             :             char        sql[64];
    3824             : 
    3825             :             /* This is a regular synchronous fetch. */
    3826        2598 :             snprintf(sql, sizeof(sql), "FETCH %d FROM c%u",
    3827             :                      fsstate->fetch_size, fsstate->cursor_number);
    3828             : 
    3829        2598 :             res = pgfdw_exec_query(conn, sql, fsstate->conn_state);
    3830             :             /* On error, report the original query, not the FETCH. */
    3831        2598 :             if (PQresultStatus(res) != PGRES_TUPLES_OK)
    3832           2 :                 pgfdw_report_error(ERROR, res, conn, false, fsstate->query);
    3833             :         }
    3834             : 
    3835             :         /* Convert the data into HeapTuples */
    3836        2912 :         numrows = PQntuples(res);
    3837        2912 :         fsstate->tuples = (HeapTuple *) palloc0(numrows * sizeof(HeapTuple));
    3838        2912 :         fsstate->num_tuples = numrows;
    3839        2912 :         fsstate->next_tuple = 0;
    3840             : 
    3841      141154 :         for (i = 0; i < numrows; i++)
    3842             :         {
    3843             :             Assert(IsA(node->ss.ps.plan, ForeignScan));
    3844             : 
    3845      276492 :             fsstate->tuples[i] =
    3846      138250 :                 make_tuple_from_result_row(res, i,
    3847             :                                            fsstate->rel,
    3848             :                                            fsstate->attinmeta,
    3849             :                                            fsstate->retrieved_attrs,
    3850             :                                            node,
    3851             :                                            fsstate->temp_cxt);
    3852             :         }
    3853             : 
    3854             :         /* Update fetch_ct_2 */
    3855        2904 :         if (fsstate->fetch_ct_2 < 2)
    3856        1836 :             fsstate->fetch_ct_2++;
    3857             : 
    3858             :         /* Must be EOF if we didn't get as many tuples as we asked for. */
    3859        2904 :         fsstate->eof_reached = (numrows < fsstate->fetch_size);
    3860             :     }
    3861          10 :     PG_FINALLY();
    3862             :     {
    3863        2914 :         PQclear(res);
    3864             :     }
    3865        2914 :     PG_END_TRY();
    3866             : 
    3867        2904 :     MemoryContextSwitchTo(oldcontext);
    3868        2904 : }
    3869             : 
    3870             : /*
    3871             :  * Force assorted GUC parameters to settings that ensure that we'll output
    3872             :  * data values in a form that is unambiguous to the remote server.
    3873             :  *
    3874             :  * This is rather expensive and annoying to do once per row, but there's
    3875             :  * little choice if we want to be sure values are transmitted accurately;
    3876             :  * we can't leave the settings in place between rows for fear of affecting
    3877             :  * user-visible computations.
    3878             :  *
    3879             :  * We use the equivalent of a function SET option to allow the settings to
    3880             :  * persist only until the caller calls reset_transmission_modes().  If an
    3881             :  * error is thrown in between, guc.c will take care of undoing the settings.
    3882             :  *
    3883             :  * The return value is the nestlevel that must be passed to
    3884             :  * reset_transmission_modes() to undo things.
    3885             :  */
    3886             : int
    3887        8004 : set_transmission_modes(void)
    3888             : {
    3889        8004 :     int         nestlevel = NewGUCNestLevel();
    3890             : 
    3891             :     /*
    3892             :      * The values set here should match what pg_dump does.  See also
    3893             :      * configure_remote_session in connection.c.
    3894             :      */
    3895        8004 :     if (DateStyle != USE_ISO_DATES)
    3896        8000 :         (void) set_config_option("datestyle", "ISO",
    3897             :                                  PGC_USERSET, PGC_S_SESSION,
    3898             :                                  GUC_ACTION_SAVE, true, 0, false);
    3899        8004 :     if (IntervalStyle != INTSTYLE_POSTGRES)
    3900        8000 :         (void) set_config_option("intervalstyle", "postgres",
    3901             :                                  PGC_USERSET, PGC_S_SESSION,
    3902             :                                  GUC_ACTION_SAVE, true, 0, false);
    3903        8004 :     if (extra_float_digits < 3)
    3904        8000 :         (void) set_config_option("extra_float_digits", "3",
    3905             :                                  PGC_USERSET, PGC_S_SESSION,
    3906             :                                  GUC_ACTION_SAVE, true, 0, false);
    3907             : 
    3908             :     /*
    3909             :      * In addition force restrictive search_path, in case there are any
    3910             :      * regproc or similar constants to be printed.
    3911             :      */
    3912        8004 :     (void) set_config_option("search_path", "pg_catalog",
    3913             :                              PGC_USERSET, PGC_S_SESSION,
    3914             :                              GUC_ACTION_SAVE, true, 0, false);
    3915             : 
    3916        8004 :     return nestlevel;
    3917             : }
    3918             : 
    3919             : /*
    3920             :  * Undo the effects of set_transmission_modes().
    3921             :  */
    3922             : void
    3923        8004 : reset_transmission_modes(int nestlevel)
    3924             : {
    3925        8004 :     AtEOXact_GUC(true, nestlevel);
    3926        8004 : }
    3927             : 
    3928             : /*
    3929             :  * Utility routine to close a cursor.
    3930             :  */
    3931             : static void
    3932         954 : close_cursor(PGconn *conn, unsigned int cursor_number,
    3933             :              PgFdwConnState *conn_state)
    3934             : {
    3935             :     char        sql[64];
    3936             :     PGresult   *res;
    3937             : 
    3938         954 :     snprintf(sql, sizeof(sql), "CLOSE c%u", cursor_number);
    3939             : 
    3940             :     /*
    3941             :      * We don't use a PG_TRY block here, so be careful not to throw error
    3942             :      * without releasing the PGresult.
    3943             :      */
    3944         954 :     res = pgfdw_exec_query(conn, sql, conn_state);
    3945         954 :     if (PQresultStatus(res) != PGRES_COMMAND_OK)
    3946           0 :         pgfdw_report_error(ERROR, res, conn, true, sql);
    3947         954 :     PQclear(res);
    3948         954 : }
    3949             : 
    3950             : /*
    3951             :  * create_foreign_modify
    3952             :  *      Construct an execution state of a foreign insert/update/delete
    3953             :  *      operation
    3954             :  */
    3955             : static PgFdwModifyState *
    3956         338 : create_foreign_modify(EState *estate,
    3957             :                       RangeTblEntry *rte,
    3958             :                       ResultRelInfo *resultRelInfo,
    3959             :                       CmdType operation,
    3960             :                       Plan *subplan,
    3961             :                       char *query,
    3962             :                       List *target_attrs,
    3963             :                       int values_end,
    3964             :                       bool has_returning,
    3965             :                       List *retrieved_attrs)
    3966             : {
    3967             :     PgFdwModifyState *fmstate;
    3968         338 :     Relation    rel = resultRelInfo->ri_RelationDesc;
    3969         338 :     TupleDesc   tupdesc = RelationGetDescr(rel);
    3970             :     Oid         userid;
    3971             :     ForeignTable *table;
    3972             :     UserMapping *user;
    3973             :     AttrNumber  n_params;
    3974             :     Oid         typefnoid;
    3975             :     bool        isvarlena;
    3976             :     ListCell   *lc;
    3977             : 
    3978             :     /* Begin constructing PgFdwModifyState. */
    3979         338 :     fmstate = (PgFdwModifyState *) palloc0(sizeof(PgFdwModifyState));
    3980         338 :     fmstate->rel = rel;
    3981             : 
    3982             :     /* Identify which user to do the remote access as. */
    3983         338 :     userid = ExecGetResultRelCheckAsUser(resultRelInfo, estate);
    3984             : 
    3985             :     /* Get info about foreign table. */
    3986         338 :     table = GetForeignTable(RelationGetRelid(rel));
    3987         338 :     user = GetUserMapping(userid, table->serverid);
    3988             : 
    3989             :     /* Open connection; report that we'll create a prepared statement. */
    3990         338 :     fmstate->conn = GetConnection(user, true, &fmstate->conn_state);
    3991         338 :     fmstate->p_name = NULL;      /* prepared statement not made yet */
    3992             : 
    3993             :     /* Set up remote query information. */
    3994         338 :     fmstate->query = query;
    3995         338 :     if (operation == CMD_INSERT)
    3996             :     {
    3997         256 :         fmstate->query = pstrdup(fmstate->query);
    3998         256 :         fmstate->orig_query = pstrdup(fmstate->query);
    3999             :     }
    4000         338 :     fmstate->target_attrs = target_attrs;
    4001         338 :     fmstate->values_end = values_end;
    4002         338 :     fmstate->has_returning = has_returning;
    4003         338 :     fmstate->retrieved_attrs = retrieved_attrs;
    4004             : 
    4005             :     /* Create context for per-tuple temp workspace. */
    4006         338 :     fmstate->temp_cxt = AllocSetContextCreate(estate->es_query_cxt,
    4007             :                                               "postgres_fdw temporary data",
    4008             :                                               ALLOCSET_SMALL_SIZES);
    4009             : 
    4010             :     /* Prepare for input conversion of RETURNING results. */
    4011         338 :     if (fmstate->has_returning)
    4012         116 :         fmstate->attinmeta = TupleDescGetAttInMetadata(tupdesc);
    4013             : 
    4014             :     /* Prepare for output conversion of parameters used in prepared stmt. */
    4015         338 :     n_params = list_length(fmstate->target_attrs) + 1;
    4016         338 :     fmstate->p_flinfo = (FmgrInfo *) palloc0(sizeof(FmgrInfo) * n_params);
    4017         338 :     fmstate->p_nums = 0;
    4018             : 
    4019         338 :     if (operation == CMD_UPDATE || operation == CMD_DELETE)
    4020             :     {
    4021             :         Assert(subplan != NULL);
    4022             : 
    4023             :         /* Find the ctid resjunk column in the subplan's result */
    4024          82 :         fmstate->ctidAttno = ExecFindJunkAttributeInTlist(subplan->targetlist,
    4025             :                                                           "ctid");
    4026          82 :         if (!AttributeNumberIsValid(fmstate->ctidAttno))
    4027           0 :             elog(ERROR, "could not find junk ctid column");
    4028             : 
    4029             :         /* First transmittable parameter will be ctid */
    4030          82 :         getTypeOutputInfo(TIDOID, &typefnoid, &isvarlena);
    4031          82 :         fmgr_info(typefnoid, &fmstate->p_flinfo[fmstate->p_nums]);
    4032          82 :         fmstate->p_nums++;
    4033             :     }
    4034             : 
    4035         338 :     if (operation == CMD_INSERT || operation == CMD_UPDATE)
    4036             :     {
    4037             :         /* Set up for remaining transmittable parameters */
    4038        1076 :         foreach(lc, fmstate->target_attrs)
    4039             :         {
    4040         758 :             int         attnum = lfirst_int(lc);
    4041         758 :             Form_pg_attribute attr = TupleDescAttr(tupdesc, attnum - 1);
    4042             : 
    4043             :             Assert(!attr->attisdropped);
    4044             : 
    4045             :             /* Ignore generated columns; they are set to DEFAULT */
    4046         758 :             if (attr->attgenerated)
    4047           8 :                 continue;
    4048         750 :             getTypeOutputInfo(attr->atttypid, &typefnoid, &isvarlena);
    4049         750 :             fmgr_info(typefnoid, &fmstate->p_flinfo[fmstate->p_nums]);
    4050         750 :             fmstate->p_nums++;
    4051             :         }
    4052             :     }
    4053             : 
    4054             :     Assert(fmstate->p_nums <= n_params);
    4055             : 
    4056             :     /* Set batch_size from foreign server/table options. */
    4057         338 :     if (operation == CMD_INSERT)
    4058         256 :         fmstate->batch_size = get_batch_size_option(rel);
    4059             : 
    4060         338 :     fmstate->num_slots = 1;
    4061             : 
    4062             :     /* Initialize auxiliary state */
    4063         338 :     fmstate->aux_fmstate = NULL;
    4064             : 
    4065         338 :     return fmstate;
    4066             : }
    4067             : 
    4068             : /*
    4069             :  * execute_foreign_modify
    4070             :  *      Perform foreign-table modification as required, and fetch RETURNING
    4071             :  *      result if any.  (This is the shared guts of postgresExecForeignInsert,
    4072             :  *      postgresExecForeignBatchInsert, postgresExecForeignUpdate, and
    4073             :  *      postgresExecForeignDelete.)
    4074             :  */
    4075             : static TupleTableSlot **
    4076        2034 : execute_foreign_modify(EState *estate,
    4077             :                        ResultRelInfo *resultRelInfo,
    4078             :                        CmdType operation,
    4079             :                        TupleTableSlot **slots,
    4080             :                        TupleTableSlot **planSlots,
    4081             :                        int *numSlots)
    4082             : {
    4083        2034 :     PgFdwModifyState *fmstate = (PgFdwModifyState *) resultRelInfo->ri_FdwState;
    4084        2034 :     ItemPointer ctid = NULL;
    4085             :     const char **p_values;
    4086             :     PGresult   *res;
    4087             :     int         n_rows;
    4088             :     StringInfoData sql;
    4089             : 
    4090             :     /* The operation should be INSERT, UPDATE, or DELETE */
    4091             :     Assert(operation == CMD_INSERT ||
    4092             :            operation == CMD_UPDATE ||
    4093             :            operation == CMD_DELETE);
    4094             : 
    4095             :     /* First, process a pending asynchronous request, if any. */
    4096        2034 :     if (fmstate->conn_state->pendingAreq)
    4097           2 :         process_pending_request(fmstate->conn_state->pendingAreq);
    4098             : 
    4099             :     /*
    4100             :      * If the existing query was deparsed and prepared for a different number
    4101             :      * of rows, rebuild it for the proper number.
    4102             :      */
    4103        2034 :     if (operation == CMD_INSERT && fmstate->num_slots != *numSlots)
    4104             :     {
    4105             :         /* Destroy the prepared statement created previously */
    4106          52 :         if (fmstate->p_name)
    4107          22 :             deallocate_query(fmstate);
    4108             : 
    4109             :         /* Build INSERT string with numSlots records in its VALUES clause. */
    4110          52 :         initStringInfo(&sql);
    4111          52 :         rebuildInsertSql(&sql, fmstate->rel,
    4112             :                          fmstate->orig_query, fmstate->target_attrs,
    4113             :                          fmstate->values_end, fmstate->p_nums,
    4114          52 :                          *numSlots - 1);
    4115          52 :         pfree(fmstate->query);
    4116          52 :         fmstate->query = sql.data;
    4117          52 :         fmstate->num_slots = *numSlots;
    4118             :     }
    4119             : 
    4120             :     /* Set up the prepared statement on the remote server, if we didn't yet */
    4121        2034 :     if (!fmstate->p_name)
    4122         348 :         prepare_foreign_modify(fmstate);
    4123             : 
    4124             :     /*
    4125             :      * For UPDATE/DELETE, get the ctid that was passed up as a resjunk column
    4126             :      */
    4127        2034 :     if (operation == CMD_UPDATE || operation == CMD_DELETE)
    4128             :     {
    4129             :         Datum       datum;
    4130             :         bool        isNull;
    4131             : 
    4132         176 :         datum = ExecGetJunkAttribute(planSlots[0],
    4133         176 :                                      fmstate->ctidAttno,
    4134             :                                      &isNull);
    4135             :         /* shouldn't ever get a null result... */
    4136         176 :         if (isNull)
    4137           0 :             elog(ERROR, "ctid is NULL");
    4138         176 :         ctid = (ItemPointer) DatumGetPointer(datum);
    4139             :     }
    4140             : 
    4141             :     /* Convert parameters needed by prepared statement to text form */
    4142        2034 :     p_values = convert_prep_stmt_params(fmstate, ctid, slots, *numSlots);
    4143             : 
    4144             :     /*
    4145             :      * Execute the prepared statement.
    4146             :      */
    4147        2034 :     if (!PQsendQueryPrepared(fmstate->conn,
    4148        2034 :                              fmstate->p_name,
    4149        2034 :                              fmstate->p_nums * (*numSlots),
    4150             :                              p_values,
    4151             :                              NULL,
    4152             :                              NULL,
    4153             :                              0))
    4154           0 :         pgfdw_report_error(ERROR, NULL, fmstate->conn, false, fmstate->query);
    4155             : 
    4156             :     /*
    4157             :      * Get the result, and check for success.
    4158             :      *
    4159             :      * We don't use a PG_TRY block here, so be careful not to throw error
    4160             :      * without releasing the PGresult.
    4161             :      */
    4162        2034 :     res = pgfdw_get_result(fmstate->conn);
    4163        4068 :     if (PQresultStatus(res) !=
    4164        2034 :         (fmstate->has_returning ? PGRES_TUPLES_OK : PGRES_COMMAND_OK))
    4165          10 :         pgfdw_report_error(ERROR, res, fmstate->conn, true, fmstate->query);
    4166             : 
    4167             :     /* Check number of rows affected, and fetch RETURNING tuple if any */
    4168        2024 :     if (fmstate->has_returning)
    4169             :     {
    4170             :         Assert(*numSlots == 1);
    4171         164 :         n_rows = PQntuples(res);
    4172         164 :         if (n_rows > 0)
    4173         162 :             store_returning_result(fmstate, slots[0], res);
    4174             :     }
    4175             :     else
    4176        1860 :         n_rows = atoi(PQcmdTuples(res));
    4177             : 
    4178             :     /* And clean up */
    4179        2024 :     PQclear(res);
    4180             : 
    4181        2024 :     MemoryContextReset(fmstate->temp_cxt);
    4182             : 
    4183        2024 :     *numSlots = n_rows;
    4184             : 
    4185             :     /*
    4186             :      * Return NULL if nothing was inserted/updated/deleted on the remote end
    4187             :      */
    4188        2024 :     return (n_rows > 0) ? slots : NULL;
    4189             : }
    4190             : 
    4191             : /*
    4192             :  * prepare_foreign_modify
    4193             :  *      Establish a prepared statement for execution of INSERT/UPDATE/DELETE
    4194             :  */
    4195             : static void
    4196         348 : prepare_foreign_modify(PgFdwModifyState *fmstate)
    4197             : {
    4198             :     char        prep_name[NAMEDATALEN];
    4199             :     char       *p_name;
    4200             :     PGresult   *res;
    4201             : 
    4202             :     /*
    4203             :      * The caller would already have processed a pending asynchronous request
    4204             :      * if any, so no need to do it here.
    4205             :      */
    4206             : 
    4207             :     /* Construct name we'll use for the prepared statement. */
    4208         348 :     snprintf(prep_name, sizeof(prep_name), "pgsql_fdw_prep_%u",
    4209             :              GetPrepStmtNumber(fmstate->conn));
    4210         348 :     p_name = pstrdup(prep_name);
    4211             : 
    4212             :     /*
    4213             :      * We intentionally do not specify parameter types here, but leave the
    4214             :      * remote server to derive them by default.  This avoids possible problems
    4215             :      * with the remote server using different type OIDs than we do.  All of
    4216             :      * the prepared statements we use in this module are simple enough that
    4217             :      * the remote server will make the right choices.
    4218             :      */
    4219         348 :     if (!PQsendPrepare(fmstate->conn,
    4220             :                        p_name,
    4221         348 :                        fmstate->query,
    4222             :                        0,
    4223             :                        NULL))
    4224           0 :         pgfdw_report_error(ERROR, NULL, fmstate->conn, false, fmstate->query);
    4225             : 
    4226             :     /*
    4227             :      * Get the result, and check for success.
    4228             :      *
    4229             :      * We don't use a PG_TRY block here, so be careful not to throw error
    4230             :      * without releasing the PGresult.
    4231             :      */
    4232         348 :     res = pgfdw_get_result(fmstate->conn);
    4233         348 :     if (PQresultStatus(res) != PGRES_COMMAND_OK)
    4234           0 :         pgfdw_report_error(ERROR, res, fmstate->conn, true, fmstate->query);
    4235         348 :     PQclear(res);
    4236             : 
    4237             :     /* This action shows that the prepare has been done. */
    4238         348 :     fmstate->p_name = p_name;
    4239         348 : }
    4240             : 
    4241             : /*
    4242             :  * convert_prep_stmt_params
    4243             :  *      Create array of text strings representing parameter values
    4244             :  *
    4245             :  * tupleid is ctid to send, or NULL if none
    4246             :  * slot is slot to get remaining parameters from, or NULL if none
    4247             :  *
    4248             :  * Data is constructed in temp_cxt; caller should reset that after use.
    4249             :  */
    4250             : static const char **
    4251        2034 : convert_prep_stmt_params(PgFdwModifyState *fmstate,
    4252             :                          ItemPointer tupleid,
    4253             :                          TupleTableSlot **slots,
    4254             :                          int numSlots)
    4255             : {
    4256             :     const char **p_values;
    4257             :     int         i;
    4258             :     int         j;
    4259        2034 :     int         pindex = 0;
    4260             :     MemoryContext oldcontext;
    4261             : 
    4262        2034 :     oldcontext = MemoryContextSwitchTo(fmstate->temp_cxt);
    4263             : 
    4264        2034 :     p_values = (const char **) palloc(sizeof(char *) * fmstate->p_nums * numSlots);
    4265             : 
    4266             :     /* ctid is provided only for UPDATE/DELETE, which don't allow batching */
    4267             :     Assert(!(tupleid != NULL && numSlots > 1));
    4268             : 
    4269             :     /* 1st parameter should be ctid, if it's in use */
    4270        2034 :     if (tupleid != NULL)
    4271             :     {
    4272             :         Assert(numSlots == 1);
    4273             :         /* don't need set_transmission_modes for TID output */
    4274         176 :         p_values[pindex] = OutputFunctionCall(&fmstate->p_flinfo[pindex],
    4275             :                                               PointerGetDatum(tupleid));
    4276         176 :         pindex++;
    4277             :     }
    4278             : 
    4279             :     /* get following parameters from slots */
    4280        2034 :     if (slots != NULL && fmstate->target_attrs != NIL)
    4281             :     {
    4282        1994 :         TupleDesc   tupdesc = RelationGetDescr(fmstate->rel);
    4283             :         int         nestlevel;
    4284             :         ListCell   *lc;
    4285             : 
    4286        1994 :         nestlevel = set_transmission_modes();
    4287             : 
    4288        4232 :         for (i = 0; i < numSlots; i++)
    4289             :         {
    4290        2238 :             j = (tupleid != NULL) ? 1 : 0;
    4291        9446 :             foreach(lc, fmstate->target_attrs)
    4292             :             {
    4293        7208 :                 int         attnum = lfirst_int(lc);
    4294        7208 :                 Form_pg_attribute attr = TupleDescAttr(tupdesc, attnum - 1);
    4295             :                 Datum       value;
    4296             :                 bool        isnull;
    4297             : 
    4298             :                 /* Ignore generated columns; they are set to DEFAULT */
    4299        7208 :                 if (attr->attgenerated)
    4300          14 :                     continue;
    4301        7194 :                 value = slot_getattr(slots[i], attnum, &isnull);
    4302        7194 :                 if (isnull)
    4303        1166 :                     p_values[pindex] = NULL;
    4304             :                 else
    4305        6028 :                     p_values[pindex] = OutputFunctionCall(&fmstate->p_flinfo[j],
    4306             :                                                           value);
    4307        7194 :                 pindex++;
    4308        7194 :                 j++;
    4309             :             }
    4310             :         }
    4311             : 
    4312        1994 :         reset_transmission_modes(nestlevel);
    4313             :     }
    4314             : 
    4315             :     Assert(pindex == fmstate->p_nums * numSlots);
    4316             : 
    4317        2034 :     MemoryContextSwitchTo(oldcontext);
    4318             : 
    4319        2034 :     return p_values;
    4320             : }
    4321             : 
    4322             : /*
    4323             :  * store_returning_result
    4324             :  *      Store the result of a RETURNING clause
    4325             :  *
    4326             :  * On error, be sure to release the PGresult on the way out.  Callers do not
    4327             :  * have PG_TRY blocks to ensure this happens.
    4328             :  */
    4329             : static void
    4330         162 : store_returning_result(PgFdwModifyState *fmstate,
    4331             :                        TupleTableSlot *slot, PGresult *res)
    4332             : {
    4333         162 :     PG_TRY();
    4334             :     {
    4335             :         HeapTuple   newtup;
    4336             : 
    4337         162 :         newtup = make_tuple_from_result_row(res, 0,
    4338             :                                             fmstate->rel,
    4339             :                                             fmstate->attinmeta,
    4340             :                                             fmstate->retrieved_attrs,
    4341             :                                             NULL,
    4342             :                                             fmstate->temp_cxt);
    4343             : 
    4344             :         /*
    4345             :          * The returning slot will not necessarily be suitable to store
    4346             :          * heaptuples directly, so allow for conversion.
    4347             :          */
    4348         162 :         ExecForceStoreHeapTuple(newtup, slot, true);
    4349             :     }
    4350           0 :     PG_CATCH();
    4351             :     {
    4352           0 :         PQclear(res);
    4353           0 :         PG_RE_THROW();
    4354             :     }
    4355         162 :     PG_END_TRY();
    4356         162 : }
    4357             : 
    4358             : /*
    4359             :  * finish_foreign_modify
    4360             :  *      Release resources for a foreign insert/update/delete operation
    4361             :  */
    4362             : static void
    4363         310 : finish_foreign_modify(PgFdwModifyState *fmstate)
    4364             : {
    4365             :     Assert(fmstate != NULL);
    4366             : 
    4367             :     /* If we created a prepared statement, destroy it */
    4368         310 :     deallocate_query(fmstate);
    4369             : 
    4370             :     /* Release remote connection */
    4371         310 :     ReleaseConnection(fmstate->conn);
    4372         310 :     fmstate->conn = NULL;
    4373         310 : }
    4374             : 
    4375             : /*
    4376             :  * deallocate_query
    4377             :  *      Deallocate a prepared statement for a foreign insert/update/delete
    4378             :  *      operation
    4379             :  */
    4380             : static void
    4381         332 : deallocate_query(PgFdwModifyState *fmstate)
    4382             : {
    4383             :     char        sql[64];
    4384             :     PGresult   *res;
    4385             : 
    4386             :     /* do nothing if the query is not allocated */
    4387         332 :     if (!fmstate->p_name)
    4388           8 :         return;
    4389             : 
    4390         324 :     snprintf(sql, sizeof(sql), "DEALLOCATE %s", fmstate->p_name);
    4391             : 
    4392             :     /*
    4393             :      * We don't use a PG_TRY block here, so be careful not to throw error
    4394             :      * without releasing the PGresult.
    4395             :      */
    4396         324 :     res = pgfdw_exec_query(fmstate->conn, sql, fmstate->conn_state);
    4397         324 :     if (PQresultStatus(res) != PGRES_COMMAND_OK)
    4398           0 :         pgfdw_report_error(ERROR, res, fmstate->conn, true, sql);
    4399         324 :     PQclear(res);
    4400         324 :     pfree(fmstate->p_name);
    4401         324 :     fmstate->p_name = NULL;
    4402             : }
    4403             : 
    4404             : /*
    4405             :  * build_remote_returning
    4406             :  *      Build a RETURNING targetlist of a remote query for performing an
    4407             :  *      UPDATE/DELETE .. RETURNING on a join directly
    4408             :  */
    4409             : static List *
    4410           8 : build_remote_returning(Index rtindex, Relation rel, List *returningList)
    4411             : {
    4412           8 :     bool        have_wholerow = false;
    4413           8 :     List       *tlist = NIL;
    4414             :     List       *vars;
    4415             :     ListCell   *lc;
    4416             : 
    4417             :     Assert(returningList);
    4418             : 
    4419           8 :     vars = pull_var_clause((Node *) returningList, PVC_INCLUDE_PLACEHOLDERS);
    4420             : 
    4421             :     /*
    4422             :      * If there's a whole-row reference to the target relation, then we'll
    4423             :      * need all the columns of the relation.
    4424             :      */
    4425           8 :     foreach(lc, vars)
    4426             :     {
    4427           4 :         Var        *var = (Var *) lfirst(lc);
    4428             : 
    4429           4 :         if (IsA(var, Var) &&
    4430           4 :             var->varno == rtindex &&
    4431           4 :             var->varattno == InvalidAttrNumber)
    4432             :         {
    4433           4 :             have_wholerow = true;
    4434           4 :             break;
    4435             :         }
    4436             :     }
    4437             : 
    4438           8 :     if (have_wholerow)
    4439             :     {
    4440           4 :         TupleDesc   tupdesc = RelationGetDescr(rel);
    4441             :         int         i;
    4442             : 
    4443          40 :         for (i = 1; i <= tupdesc->natts; i++)
    4444             :         {
    4445          36 :             Form_pg_attribute attr = TupleDescAttr(tupdesc, i - 1);
    4446             :             Var        *var;
    4447             : 
    4448             :             /* Ignore dropped attributes. */
    4449          36 :             if (attr->attisdropped)
    4450           4 :                 continue;
    4451             : 
    4452          32 :             var = makeVar(rtindex,
    4453             :                           i,
    4454             :                           attr->atttypid,
    4455             :                           attr->atttypmod,
    4456             :                           attr->attcollation,
    4457             :                           0);
    4458             : 
    4459          32 :             tlist = lappend(tlist,
    4460          32 :                             makeTargetEntry((Expr *) var,
    4461          32 :                                             list_length(tlist) + 1,
    4462             :                                             NULL,
    4463             :                                             false));
    4464             :         }
    4465             :     }
    4466             : 
    4467             :     /* Now add any remaining columns to tlist. */
    4468          60 :     foreach(lc, vars)
    4469             :     {
    4470          52 :         Var        *var = (Var *) lfirst(lc);
    4471             : 
    4472             :         /*
    4473             :          * No need for whole-row references to the target relation.  We don't
    4474             :          * need system columns other than ctid and oid either, since those are
    4475             :          * set locally.
    4476             :          */
    4477          52 :         if (IsA(var, Var) &&
    4478          52 :             var->varno == rtindex &&
    4479          36 :             var->varattno <= InvalidAttrNumber &&
    4480           4 :             var->varattno != SelfItemPointerAttributeNumber)
    4481           4 :             continue;           /* don't need it */
    4482             : 
    4483          48 :         if (tlist_member((Expr *) var, tlist))
    4484          32 :             continue;           /* already got it */
    4485             : 
    4486          16 :         tlist = lappend(tlist,
    4487          16 :                         makeTargetEntry((Expr *) var,
    4488          16 :                                         list_length(tlist) + 1,
    4489             :                                         NULL,
    4490             :                                         false));
    4491             :     }
    4492             : 
    4493           8 :     list_free(vars);
    4494             : 
    4495           8 :     return tlist;
    4496             : }
    4497             : 
    4498             : /*
    4499             :  * rebuild_fdw_scan_tlist
    4500             :  *      Build new fdw_scan_tlist of given foreign-scan plan node from given
    4501             :  *      tlist
    4502             :  *
    4503             :  * There might be columns that the fdw_scan_tlist of the given foreign-scan
    4504             :  * plan node contains that the given tlist doesn't.  The fdw_scan_tlist would
    4505             :  * have contained resjunk columns such as 'ctid' of the target relation and
    4506             :  * 'wholerow' of non-target relations, but the tlist might not contain them,
    4507             :  * for example.  So, adjust the tlist so it contains all the columns specified
    4508             :  * in the fdw_scan_tlist; else setrefs.c will get confused.
    4509             :  */
    4510             : static void
    4511           4 : rebuild_fdw_scan_tlist(ForeignScan *fscan, List *tlist)
    4512             : {
    4513           4 :     List       *new_tlist = tlist;
    4514           4 :     List       *old_tlist = fscan->fdw_scan_tlist;
    4515             :     ListCell   *lc;
    4516             : 
    4517          32 :     foreach(lc, old_tlist)
    4518             :     {
    4519          28 :         TargetEntry *tle = (TargetEntry *) lfirst(lc);
    4520             : 
    4521          28 :         if (tlist_member(tle->expr, new_tlist))
    4522          16 :             continue;           /* already got it */
    4523             : 
    4524          12 :         new_tlist = lappend(new_tlist,
    4525          12 :                             makeTargetEntry(tle->expr,
    4526          12 :                                             list_length(new_tlist) + 1,
    4527             :                                             NULL,
    4528             :                                             false));
    4529             :     }
    4530           4 :     fscan->fdw_scan_tlist = new_tlist;
    4531           4 : }
    4532             : 
    4533             : /*
    4534             :  * Execute a direct UPDATE/DELETE statement.
    4535             :  */
    4536             : static void
    4537         142 : execute_dml_stmt(ForeignScanState *node)
    4538             : {
    4539         142 :     PgFdwDirectModifyState *dmstate = (PgFdwDirectModifyState *) node->fdw_state;
    4540         142 :     ExprContext *econtext = node->ss.ps.ps_ExprContext;
    4541         142 :     int         numParams = dmstate->numParams;
    4542         142 :     const char **values = dmstate->param_values;
    4543             : 
    4544             :     /* First, process a pending asynchronous request, if any. */
    4545         142 :     if (dmstate->conn_state->pendingAreq)
    4546           2 :         process_pending_request(dmstate->conn_state->pendingAreq);
    4547             : 
    4548             :     /*
    4549             :      * Construct array of query parameter values in text format.
    4550             :      */
    4551         142 :     if (numParams > 0)
    4552           0 :         process_query_params(econtext,
    4553             :                              dmstate->param_flinfo,
    4554             :                              dmstate->param_exprs,
    4555             :                              values);
    4556             : 
    4557             :     /*
    4558             :      * Notice that we pass NULL for paramTypes, thus forcing the remote server
    4559             :      * to infer types for all parameters.  Since we explicitly cast every
    4560             :      * parameter (see deparse.c), the "inference" is trivial and will produce
    4561             :      * the desired result.  This allows us to avoid assuming that the remote
    4562             :      * server has the same OIDs we do for the parameters' types.
    4563             :      */
    4564         142 :     if (!PQsendQueryParams(dmstate->conn, dmstate->query, numParams,
    4565             :                            NULL, values, NULL, NULL, 0))
    4566           0 :         pgfdw_report_error(ERROR, NULL, dmstate->conn, false, dmstate->query);
    4567             : 
    4568             :     /*
    4569             :      * Get the result, and check for success.
    4570             :      *
    4571             :      * We don't use a PG_TRY block here, so be careful not to throw error
    4572             :      * without releasing the PGresult.
    4573             :      */
    4574         142 :     dmstate->result = pgfdw_get_result(dmstate->conn);
    4575         284 :     if (PQresultStatus(dmstate->result) !=
    4576         142 :         (dmstate->has_returning ? PGRES_TUPLES_OK : PGRES_COMMAND_OK))
    4577           8 :         pgfdw_report_error(ERROR, dmstate->result, dmstate->conn, true,
    4578           8 :                            dmstate->query);
    4579             : 
    4580             :     /* Get the number of rows affected. */
    4581         134 :     if (dmstate->has_returning)
    4582          28 :         dmstate->num_tuples = PQntuples(dmstate->result);
    4583             :     else
    4584         106 :         dmstate->num_tuples = atoi(PQcmdTuples(dmstate->result));
    4585         134 : }
    4586             : 
    4587             : /*
    4588             :  * Get the result of a RETURNING clause.
    4589             :  */
    4590             : static TupleTableSlot *
    4591         728 : get_returning_data(ForeignScanState *node)
    4592             : {
    4593         728 :     PgFdwDirectModifyState *dmstate = (PgFdwDirectModifyState *) node->fdw_state;
    4594         728 :     EState     *estate = node->ss.ps.state;
    4595         728 :     ResultRelInfo *resultRelInfo = node->resultRelInfo;
    4596         728 :     TupleTableSlot *slot = node->ss.ss_ScanTupleSlot;
    4597             :     TupleTableSlot *resultSlot;
    4598             : 
    4599             :     Assert(resultRelInfo->ri_projectReturning);
    4600             : 
    4601             :     /* If we didn't get any tuples, must be end of data. */
    4602         728 :     if (dmstate->next_tuple >= dmstate->num_tuples)
    4603          34 :         return ExecClearTuple(slot);
    4604             : 
    4605             :     /* Increment the command es_processed count if necessary. */
    4606         694 :     if (dmstate->set_processed)
    4607         692 :         estate->es_processed += 1;
    4608             : 
    4609             :     /*
    4610             :      * Store a RETURNING tuple.  If has_returning is false, just emit a dummy
    4611             :      * tuple.  (has_returning is false when the local query is of the form
    4612             :      * "UPDATE/DELETE .. RETURNING 1" for example.)
    4613             :      */
    4614         694 :     if (!dmstate->has_returning)
    4615             :     {
    4616          24 :         ExecStoreAllNullTuple(slot);
    4617          24 :         resultSlot = slot;
    4618             :     }
    4619             :     else
    4620             :     {
    4621             :         /*
    4622             :          * On error, be sure to release the PGresult on the way out.  Callers
    4623             :          * do not have PG_TRY blocks to ensure this happens.
    4624             :          */
    4625         670 :         PG_TRY();
    4626             :         {
    4627             :             HeapTuple   newtup;
    4628             : 
    4629         670 :             newtup = make_tuple_from_result_row(dmstate->result,
    4630             :                                                 dmstate->next_tuple,
    4631             :                                                 dmstate->rel,
    4632             :                                                 dmstate->attinmeta,
    4633             :                                                 dmstate->retrieved_attrs,
    4634             :                                                 node,
    4635             :                                                 dmstate->temp_cxt);
    4636         670 :             ExecStoreHeapTuple(newtup, slot, false);
    4637             :         }
    4638           0 :         PG_CATCH();
    4639             :         {
    4640           0 :             PQclear(dmstate->result);
    4641           0 :             PG_RE_THROW();
    4642             :         }
    4643         670 :         PG_END_TRY();
    4644             : 
    4645             :         /* Get the updated/deleted tuple. */
    4646         670 :         if (dmstate->rel)
    4647         638 :             resultSlot = slot;
    4648             :         else
    4649          32 :             resultSlot = apply_returning_filter(dmstate, resultRelInfo, slot, estate);
    4650             :     }
    4651         694 :     dmstate->next_tuple++;
    4652             : 
    4653             :     /* Make slot available for evaluation of the local query RETURNING list. */
    4654         694 :     resultRelInfo->ri_projectReturning->pi_exprContext->ecxt_scantuple =
    4655             :         resultSlot;
    4656             : 
    4657         694 :     return slot;
    4658             : }
    4659             : 
    4660             : /*
    4661             :  * Initialize a filter to extract an updated/deleted tuple from a scan tuple.
    4662             :  */
    4663             : static void
    4664           2 : init_returning_filter(PgFdwDirectModifyState *dmstate,
    4665             :                       List *fdw_scan_tlist,
    4666             :                       Index rtindex)
    4667             : {
    4668           2 :     TupleDesc   resultTupType = RelationGetDescr(dmstate->resultRel);
    4669             :     ListCell   *lc;
    4670             :     int         i;
    4671             : 
    4672             :     /*
    4673             :      * Calculate the mapping between the fdw_scan_tlist's entries and the
    4674             :      * result tuple's attributes.
    4675             :      *
    4676             :      * The "map" is an array of indexes of the result tuple's attributes in
    4677             :      * fdw_scan_tlist, i.e., one entry for every attribute of the result
    4678             :      * tuple.  We store zero for any attributes that don't have the
    4679             :      * corresponding entries in that list, marking that a NULL is needed in
    4680             :      * the result tuple.
    4681             :      *
    4682             :      * Also get the indexes of the entries for ctid and oid if any.
    4683             :      */
    4684           2 :     dmstate->attnoMap = (AttrNumber *)
    4685           2 :         palloc0(resultTupType->natts * sizeof(AttrNumber));
    4686             : 
    4687           2 :     dmstate->ctidAttno = dmstate->oidAttno = 0;
    4688             : 
    4689           2 :     i = 1;
    4690           2 :     dmstate->hasSystemCols = false;
    4691          32 :     foreach(lc, fdw_scan_tlist)
    4692             :     {
    4693          30 :         TargetEntry *tle = (TargetEntry *) lfirst(lc);
    4694          30 :         Var        *var = (Var *) tle->expr;
    4695             : 
    4696             :         Assert(IsA(var, Var));
    4697             : 
    4698             :         /*
    4699             :          * If the Var is a column of the target relation to be retrieved from
    4700             :          * the foreign server, get the index of the entry.
    4701             :          */
    4702          50 :         if (var->varno == rtindex &&
    4703          20 :             list_member_int(dmstate->retrieved_attrs, i))
    4704             :         {
    4705          16 :             int         attrno = var->varattno;
    4706             : 
    4707          16 :             if (attrno < 0)
    4708             :             {
    4709             :                 /*
    4710             :                  * We don't retrieve system columns other than ctid and oid.
    4711             :                  */
    4712           0 :                 if (attrno == SelfItemPointerAttributeNumber)
    4713           0 :                     dmstate->ctidAttno = i;
    4714             :                 else
    4715             :                     Assert(false);
    4716           0 :                 dmstate->hasSystemCols = true;
    4717             :             }
    4718             :             else
    4719             :             {
    4720             :                 /*
    4721             :                  * We don't retrieve whole-row references to the target
    4722             :                  * relation either.
    4723             :                  */
    4724             :                 Assert(attrno > 0);
    4725             : 
    4726          16 :                 dmstate->attnoMap[attrno - 1] = i;
    4727             :             }
    4728             :         }
    4729          30 :         i++;
    4730             :     }
    4731           2 : }
    4732             : 
    4733             : /*
    4734             :  * Extract and return an updated/deleted tuple from a scan tuple.
    4735             :  */
    4736             : static TupleTableSlot *
    4737          32 : apply_returning_filter(PgFdwDirectModifyState *dmstate,
    4738             :                        ResultRelInfo *resultRelInfo,
    4739             :                        TupleTableSlot *slot,
    4740             :                        EState *estate)
    4741             : {
    4742          32 :     TupleDesc   resultTupType = RelationGetDescr(dmstate->resultRel);
    4743             :     TupleTableSlot *resultSlot;
    4744             :     Datum      *values;
    4745             :     bool       *isnull;
    4746             :     Datum      *old_values;
    4747             :     bool       *old_isnull;
    4748             :     int         i;
    4749             : 
    4750             :     /*
    4751             :      * Use the return tuple slot as a place to store the result tuple.
    4752             :      */
    4753          32 :     resultSlot = ExecGetReturningSlot(estate, resultRelInfo);
    4754             : 
    4755             :     /*
    4756             :      * Extract all the values of the scan tuple.
    4757             :      */
    4758          32 :     slot_getallattrs(slot);
    4759          32 :     old_values = slot->tts_values;
    4760          32 :     old_isnull = slot->tts_isnull;
    4761             : 
    4762             :     /*
    4763             :      * Prepare to build the result tuple.
    4764             :      */
    4765          32 :     ExecClearTuple(resultSlot);
    4766          32 :     values = resultSlot->tts_values;
    4767          32 :     isnull = resultSlot->tts_isnull;
    4768             : 
    4769             :     /*
    4770             :      * Transpose data into proper fields of the result tuple.
    4771             :      */
    4772         320 :     for (i = 0; i < resultTupType->natts; i++)
    4773             :     {
    4774         288 :         int         j = dmstate->attnoMap[i];
    4775             : 
    4776         288 :         if (j == 0)
    4777             :         {
    4778          32 :             values[i] = (Datum) 0;
    4779          32 :             isnull[i] = true;
    4780             :         }
    4781             :         else
    4782             :         {
    4783         256 :             values[i] = old_values[j - 1];
    4784         256 :             isnull[i] = old_isnull[j - 1];
    4785             :         }
    4786             :     }
    4787             : 
    4788             :     /*
    4789             :      * Build the virtual tuple.
    4790             :      */
    4791          32 :     ExecStoreVirtualTuple(resultSlot);
    4792             : 
    4793             :     /*
    4794             :      * If we have any system columns to return, materialize a heap tuple in
    4795             :      * the slot from column values set above and install system columns in
    4796             :      * that tuple.
    4797             :      */
    4798          32 :     if (dmstate->hasSystemCols)
    4799             :     {
    4800           0 :         HeapTuple   resultTup = ExecFetchSlotHeapTuple(resultSlot, true, NULL);
    4801             : 
    4802             :         /* ctid */
    4803           0 :         if (dmstate->ctidAttno)
    4804             :         {
    4805           0 :             ItemPointer ctid = NULL;
    4806             : 
    4807           0 :             ctid = (ItemPointer) DatumGetPointer(old_values[dmstate->ctidAttno - 1]);
    4808           0 :             resultTup->t_self = *ctid;
    4809             :         }
    4810             : 
    4811             :         /*
    4812             :          * And remaining columns
    4813             :          *
    4814             :          * Note: since we currently don't allow the target relation to appear
    4815             :          * on the nullable side of an outer join, any system columns wouldn't
    4816             :          * go to NULL.
    4817             :          *
    4818             :          * Note: no need to care about tableoid here because it will be
    4819             :          * initialized in ExecProcessReturning().
    4820             :          */
    4821           0 :         HeapTupleHeaderSetXmin(resultTup->t_data, InvalidTransactionId);
    4822           0 :         HeapTupleHeaderSetXmax(resultTup->t_data, InvalidTransactionId);
    4823           0 :         HeapTupleHeaderSetCmin(resultTup->t_data, InvalidTransactionId);
    4824             :     }
    4825             : 
    4826             :     /*
    4827             :      * And return the result tuple.
    4828             :      */
    4829          32 :     return resultSlot;
    4830             : }
    4831             : 
    4832             : /*
    4833             :  * Prepare for processing of parameters used in remote query.
    4834             :  */
    4835             : static void
    4836          36 : prepare_query_params(PlanState *node,
    4837             :                      List *fdw_exprs,
    4838             :                      int numParams,
    4839             :                      FmgrInfo **param_flinfo,
    4840             :                      List **param_exprs,
    4841             :                      const char ***param_values)
    4842             : {
    4843             :     int         i;
    4844             :     ListCell   *lc;
    4845             : 
    4846             :     Assert(numParams > 0);
    4847             : 
    4848             :     /* Prepare for output conversion of parameters used in remote query. */
    4849          36 :     *param_flinfo = (FmgrInfo *) palloc0(sizeof(FmgrInfo) * numParams);
    4850             : 
    4851          36 :     i = 0;
    4852          74 :     foreach(lc, fdw_exprs)
    4853             :     {
    4854          38 :         Node       *param_expr = (Node *) lfirst(lc);
    4855             :         Oid         typefnoid;
    4856             :         bool        isvarlena;
    4857             : 
    4858          38 :         getTypeOutputInfo(exprType(param_expr), &typefnoid, &isvarlena);
    4859          38 :         fmgr_info(typefnoid, &(*param_flinfo)[i]);
    4860          38 :         i++;
    4861             :     }
    4862             : 
    4863             :     /*
    4864             :      * Prepare remote-parameter expressions for evaluation.  (Note: in
    4865             :      * practice, we expect that all these expressions will be just Params, so
    4866             :      * we could possibly do something more efficient than using the full
    4867             :      * expression-eval machinery for this.  But probably there would be little
    4868             :      * benefit, and it'd require postgres_fdw to know more than is desirable
    4869             :      * about Param evaluation.)
    4870             :      */
    4871          36 :     *param_exprs = ExecInitExprList(fdw_exprs, node);
    4872             : 
    4873             :     /* Allocate buffer for text form of query parameters. */
    4874          36 :     *param_values = (const char **) palloc0(numParams * sizeof(char *));
    4875          36 : }
    4876             : 
    4877             : /*
    4878             :  * Construct array of query parameter values in text format.
    4879             :  */
    4880             : static void
    4881         692 : process_query_params(ExprContext *econtext,
    4882             :                      FmgrInfo *param_flinfo,
    4883             :                      List *param_exprs,
    4884             :                      const char **param_values)
    4885             : {
    4886             :     int         nestlevel;
    4887             :     int         i;
    4888             :     ListCell   *lc;
    4889             : 
    4890         692 :     nestlevel = set_transmission_modes();
    4891             : 
    4892         692 :     i = 0;
    4893        1784 :     foreach(lc, param_exprs)
    4894             :     {
    4895        1092 :         ExprState  *expr_state = (ExprState *) lfirst(lc);
    4896             :         Datum       expr_value;
    4897             :         bool        isNull;
    4898             : 
    4899             :         /* Evaluate the parameter expression */
    4900        1092 :         expr_value = ExecEvalExpr(expr_state, econtext, &isNull);
    4901             : 
    4902             :         /*
    4903             :          * Get string representation of each parameter value by invoking
    4904             :          * type-specific output function, unless the value is null.
    4905             :          */
    4906        1092 :         if (isNull)
    4907           0 :             param_values[i] = NULL;
    4908             :         else
    4909        1092 :             param_values[i] = OutputFunctionCall(&param_flinfo[i], expr_value);
    4910             : 
    4911        1092 :         i++;
    4912             :     }
    4913             : 
    4914         692 :     reset_transmission_modes(nestlevel);
    4915         692 : }
    4916             : 
    4917             : /*
    4918             :  * postgresAnalyzeForeignTable
    4919             :  *      Test whether analyzing this foreign table is supported
    4920             :  */
    4921             : static bool
    4922          80 : postgresAnalyzeForeignTable(Relation relation,
    4923             :                             AcquireSampleRowsFunc *func,
    4924             :                             BlockNumber *totalpages)
    4925             : {
    4926             :     ForeignTable *table;
    4927             :     UserMapping *user;
    4928             :     PGconn     *conn;
    4929             :     StringInfoData sql;
    4930          80 :     PGresult   *volatile res = NULL;
    4931             : 
    4932             :     /* Return the row-analysis function pointer */
    4933          80 :     *func = postgresAcquireSampleRowsFunc;
    4934             : 
    4935             :     /*
    4936             :      * Now we have to get the number of pages.  It's annoying that the ANALYZE
    4937             :      * API requires us to return that now, because it forces some duplication
    4938             :      * of effort between this routine and postgresAcquireSampleRowsFunc.  But
    4939             :      * it's probably not worth redefining that API at this point.
    4940             :      */
    4941             : 
    4942             :     /*
    4943             :      * Get the connection to use.  We do the remote access as the table's
    4944             :      * owner, even if the ANALYZE was started by some other user.
    4945             :      */
    4946          80 :     table = GetForeignTable(RelationGetRelid(relation));
    4947          80 :     user = GetUserMapping(relation->rd_rel->relowner, table->serverid);
    4948          80 :     conn = GetConnection(user, false, NULL);
    4949             : 
    4950             :     /*
    4951             :      * Construct command to get page count for relation.
    4952             :      */
    4953          80 :     initStringInfo(&sql);
    4954          80 :     deparseAnalyzeSizeSql(&sql, relation);
    4955             : 
    4956             :     /* In what follows, do not risk leaking any PGresults. */
    4957          80 :     PG_TRY();
    4958             :     {
    4959          80 :         res = pgfdw_exec_query(conn, sql.data, NULL);
    4960          80 :         if (PQresultStatus(res) != PGRES_TUPLES_OK)
    4961           0 :             pgfdw_report_error(ERROR, res, conn, false, sql.data);
    4962             : 
    4963          80 :         if (PQntuples(res) != 1 || PQnfields(res) != 1)
    4964           0 :             elog(ERROR, "unexpected result from deparseAnalyzeSizeSql query");
    4965          80 :         *totalpages = strtoul(PQgetvalue(res, 0, 0), NULL, 10);
    4966             :     }
    4967           0 :     PG_FINALLY();
    4968             :     {
    4969          80 :         PQclear(res);
    4970             :     }
    4971          80 :     PG_END_TRY();
    4972             : 
    4973          80 :     ReleaseConnection(conn);
    4974             : 
    4975          80 :     return true;
    4976             : }
    4977             : 
    4978             : /*
    4979             :  * postgresGetAnalyzeInfoForForeignTable
    4980             :  *      Count tuples in foreign table (just get pg_class.reltuples).
    4981             :  *
    4982             :  * can_tablesample determines if the remote relation supports acquiring the
    4983             :  * sample using TABLESAMPLE.
    4984             :  */
    4985             : static double
    4986          80 : postgresGetAnalyzeInfoForForeignTable(Relation relation, bool *can_tablesample)
    4987             : {
    4988             :     ForeignTable *table;
    4989             :     UserMapping *user;
    4990             :     PGconn     *conn;
    4991             :     StringInfoData sql;
    4992          80 :     PGresult   *volatile res = NULL;
    4993          80 :     volatile double reltuples = -1;
    4994          80 :     volatile char relkind = 0;
    4995             : 
    4996             :     /* assume the remote relation does not support TABLESAMPLE */
    4997          80 :     *can_tablesample = false;
    4998             : 
    4999             :     /*
    5000             :      * Get the connection to use.  We do the remote access as the table's
    5001             :      * owner, even if the ANALYZE was started by some other user.
    5002             :      */
    5003          80 :     table = GetForeignTable(RelationGetRelid(relation));
    5004          80 :     user = GetUserMapping(relation->rd_rel->relowner, table->serverid);
    5005          80 :     conn = GetConnection(user, false, NULL);
    5006             : 
    5007             :     /*
    5008             :      * Construct command to get page count for relation.
    5009             :      */
    5010          80 :     initStringInfo(&sql);
    5011          80 :     deparseAnalyzeInfoSql(&sql, relation);
    5012             : 
    5013             :     /* In what follows, do not risk leaking any PGresults. */
    5014          80 :     PG_TRY();
    5015             :     {
    5016          80 :         res = pgfdw_exec_query(conn, sql.data, NULL);
    5017          80 :         if (PQresultStatus(res) != PGRES_TUPLES_OK)
    5018           0 :             pgfdw_report_error(ERROR, res, conn, false, sql.data);
    5019             : 
    5020          80 :         if (PQntuples(res) != 1 || PQnfields(res) != 2)
    5021           0 :             elog(ERROR, "unexpected result from deparseAnalyzeInfoSql query");
    5022          80 :         reltuples = strtod(PQgetvalue(res, 0, 0), NULL);
    5023          80 :         relkind = *(PQgetvalue(res, 0, 1));
    5024             :     }
    5025           0 :     PG_FINALLY();
    5026             :     {
    5027          80 :         if (res)
    5028          80 :             PQclear(res);
    5029             :     }
    5030          80 :     PG_END_TRY();
    5031             : 
    5032          80 :     ReleaseConnection(conn);
    5033             : 
    5034             :     /* TABLESAMPLE is supported only for regular tables and matviews */
    5035         160 :     *can_tablesample = (relkind == RELKIND_RELATION ||
    5036          80 :                         relkind == RELKIND_MATVIEW ||
    5037           0 :                         relkind == RELKIND_PARTITIONED_TABLE);
    5038             : 
    5039          80 :     return reltuples;
    5040             : }
    5041             : 
    5042             : /*
    5043             :  * Acquire a random sample of rows from foreign table managed by postgres_fdw.
    5044             :  *
    5045             :  * Selected rows are returned in the caller-allocated array rows[],
    5046             :  * which must have at least targrows entries.
    5047             :  * The actual number of rows selected is returned as the function result.
    5048             :  * We also count the total number of rows in the table and return it into
    5049             :  * *totalrows.  Note that *totaldeadrows is always set to 0.
    5050             :  *
    5051             :  * Note that the returned list of rows is not always in order by physical
    5052             :  * position in the table.  Therefore, correlation estimates derived later
    5053             :  * may be meaningless, but it's OK because we don't use the estimates
    5054             :  * currently (the planner only pays attention to correlation for indexscans).
    5055             :  */
    5056             : static int
    5057          80 : postgresAcquireSampleRowsFunc(Relation relation, int elevel,
    5058             :                               HeapTuple *rows, int targrows,
    5059             :                               double *totalrows,
    5060             :                               double *totaldeadrows)
    5061             : {
    5062             :     PgFdwAnalyzeState astate;
    5063             :     ForeignTable *table;
    5064             :     ForeignServer *server;
    5065             :     UserMapping *user;
    5066             :     PGconn     *conn;
    5067             :     int         server_version_num;
    5068          80 :     PgFdwSamplingMethod method = ANALYZE_SAMPLE_AUTO;   /* auto is default */
    5069          80 :     double      sample_frac = -1.0;
    5070             :     double      reltuples;
    5071             :     unsigned int cursor_number;
    5072             :     StringInfoData sql;
    5073          80 :     PGresult   *volatile res = NULL;
    5074             :     ListCell   *lc;
    5075             : 
    5076             :     /* Initialize workspace state */
    5077          80 :     astate.rel = relation;
    5078          80 :     astate.attinmeta = TupleDescGetAttInMetadata(RelationGetDescr(relation));
    5079             : 
    5080          80 :     astate.rows = rows;
    5081          80 :     astate.targrows = targrows;
    5082          80 :     astate.numrows = 0;
    5083          80 :     astate.samplerows = 0;
    5084          80 :     astate.rowstoskip = -1;     /* -1 means not set yet */
    5085          80 :     reservoir_init_selection_state(&astate.rstate, targrows);
    5086             : 
    5087             :     /* Remember ANALYZE context, and create a per-tuple temp context */
    5088          80 :     astate.anl_cxt = CurrentMemoryContext;
    5089          80 :     astate.temp_cxt = AllocSetContextCreate(CurrentMemoryContext,
    5090             :                                             "postgres_fdw temporary data",
    5091             :                                             ALLOCSET_SMALL_SIZES);
    5092             : 
    5093             :     /*
    5094             :      * Get the connection to use.  We do the remote access as the table's
    5095             :      * owner, even if the ANALYZE was started by some other user.
    5096             :      */
    5097          80 :     table = GetForeignTable(RelationGetRelid(relation));
    5098          80 :     server = GetForeignServer(table->serverid);
    5099          80 :     user = GetUserMapping(relation->rd_rel->relowner, table->serverid);
    5100          80 :     conn = GetConnection(user, false, NULL);
    5101             : 
    5102             :     /* We'll need server version, so fetch it now. */
    5103          80 :     server_version_num = PQserverVersion(conn);
    5104             : 
    5105             :     /*
    5106             :      * What sampling method should we use?
    5107             :      */
    5108         352 :     foreach(lc, server->options)
    5109             :     {
    5110         272 :         DefElem    *def = (DefElem *) lfirst(lc);
    5111             : 
    5112         272 :         if (strcmp(def->defname, "analyze_sampling") == 0)
    5113             :         {
    5114           0 :             char       *value = defGetString(def);
    5115             : 
    5116           0 :             if (strcmp(value, "off") == 0)
    5117           0 :                 method = ANALYZE_SAMPLE_OFF;
    5118           0 :             else if (strcmp(value, "auto") == 0)
    5119           0 :                 method = ANALYZE_SAMPLE_AUTO;
    5120           0 :             else if (strcmp(value, "random") == 0)
    5121           0 :                 method = ANALYZE_SAMPLE_RANDOM;
    5122           0 :             else if (strcmp(value, "system") == 0)
    5123           0 :                 method = ANALYZE_SAMPLE_SYSTEM;
    5124           0 :             else if (strcmp(value, "bernoulli") == 0)
    5125           0 :                 method = ANALYZE_SAMPLE_BERNOULLI;
    5126             : 
    5127           0 :             break;
    5128             :         }
    5129             :     }
    5130             : 
    5131         186 :     foreach(lc, table->options)
    5132             :     {
    5133         106 :         DefElem    *def = (DefElem *) lfirst(lc);
    5134             : 
    5135         106 :         if (strcmp(def->defname, "analyze_sampling") == 0)
    5136             :         {
    5137           0 :             char       *value = defGetString(def);
    5138             : 
    5139           0 :             if (strcmp(value, "off") == 0)
    5140           0 :                 method = ANALYZE_SAMPLE_OFF;
    5141           0 :             else if (strcmp(value, "auto") == 0)
    5142           0 :                 method = ANALYZE_SAMPLE_AUTO;
    5143           0 :             else if (strcmp(value, "random") == 0)
    5144           0 :                 method = ANALYZE_SAMPLE_RANDOM;
    5145           0 :             else if (strcmp(value, "system") == 0)
    5146           0 :                 method = ANALYZE_SAMPLE_SYSTEM;
    5147           0 :             else if (strcmp(value, "bernoulli") == 0)
    5148           0 :                 method = ANALYZE_SAMPLE_BERNOULLI;
    5149             : 
    5150           0 :             break;
    5151             :         }
    5152             :     }
    5153             : 
    5154             :     /*
    5155             :      * Error-out if explicitly required one of the TABLESAMPLE methods, but
    5156             :      * the server does not support it.
    5157             :      */
    5158          80 :     if ((server_version_num < 95000) &&
    5159           0 :         (method == ANALYZE_SAMPLE_SYSTEM ||
    5160             :          method == ANALYZE_SAMPLE_BERNOULLI))
    5161           0 :         ereport(ERROR,
    5162             :                 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
    5163             :                  errmsg("remote server does not support TABLESAMPLE feature")));
    5164             : 
    5165             :     /*
    5166             :      * If we've decided to do remote sampling, calculate the sampling rate. We
    5167             :      * need to get the number of tuples from the remote server, but skip that
    5168             :      * network round-trip if not needed.
    5169             :      */
    5170          80 :     if (method != ANALYZE_SAMPLE_OFF)
    5171             :     {
    5172             :         bool        can_tablesample;
    5173             : 
    5174          80 :         reltuples = postgresGetAnalyzeInfoForForeignTable(relation,
    5175             :                                                           &can_tablesample);
    5176             : 
    5177             :         /*
    5178             :          * Make sure we're not choosing TABLESAMPLE when the remote relation
    5179             :          * does not support that. But only do this for "auto" - if the user
    5180             :          * explicitly requested BERNOULLI/SYSTEM, it's better to fail.
    5181             :          */
    5182          80 :         if (!can_tablesample && (method == ANALYZE_SAMPLE_AUTO))
    5183           0 :             method = ANALYZE_SAMPLE_RANDOM;
    5184             : 
    5185             :         /*
    5186             :          * Remote's reltuples could be 0 or -1 if the table has never been
    5187             :          * vacuumed/analyzed.  In that case, disable sampling after all.
    5188             :          */
    5189          80 :         if ((reltuples <= 0) || (targrows >= reltuples))
    5190          80 :             method = ANALYZE_SAMPLE_OFF;
    5191             :         else
    5192             :         {
    5193             :             /*
    5194             :              * All supported sampling methods require sampling rate, not
    5195             :              * target rows directly, so we calculate that using the remote
    5196             :              * reltuples value. That's imperfect, because it might be off a
    5197             :              * good deal, but that's not something we can (or should) address
    5198             :              * here.
    5199             :              *
    5200             :              * If reltuples is too low (i.e. when table grew), we'll end up
    5201             :              * sampling more rows - but then we'll apply the local sampling,
    5202             :              * so we get the expected sample size. This is the same outcome as
    5203             :              * without remote sampling.
    5204             :              *
    5205             :              * If reltuples is too high (e.g. after bulk DELETE), we will end
    5206             :              * up sampling too few rows.
    5207             :              *
    5208             :              * We can't really do much better here - we could try sampling a
    5209             :              * bit more rows, but we don't know how off the reltuples value is
    5210             :              * so how much is "a bit more"?
    5211             :              *
    5212             :              * Furthermore, the targrows value for partitions is determined
    5213             :              * based on table size (relpages), which can be off in different
    5214             :              * ways too. Adjusting the sampling rate here might make the issue
    5215             :              * worse.
    5216             :              */
    5217           0 :             sample_frac = targrows / reltuples;
    5218             : 
    5219             :             /*
    5220             :              * We should never get sampling rate outside the valid range
    5221             :              * (between 0.0 and 1.0), because those cases should be covered by
    5222             :              * the previous branch that sets ANALYZE_SAMPLE_OFF.
    5223             :              */
    5224             :             Assert(sample_frac >= 0.0 && sample_frac <= 1.0);
    5225             :         }
    5226             :     }
    5227             : 
    5228             :     /*
    5229             :      * For "auto" method, pick the one we believe is best. For servers with
    5230             :      * TABLESAMPLE support we pick BERNOULLI, for old servers we fall-back to
    5231             :      * random() to at least reduce network transfer.
    5232             :      */
    5233          80 :     if (method == ANALYZE_SAMPLE_AUTO)
    5234             :     {
    5235           0 :         if (server_version_num < 95000)
    5236           0 :             method = ANALYZE_SAMPLE_RANDOM;
    5237             :         else
    5238           0 :             method = ANALYZE_SAMPLE_BERNOULLI;
    5239             :     }
    5240             : 
    5241             :     /*
    5242             :      * Construct cursor that retrieves whole rows from remote.
    5243             :      */
    5244          80 :     cursor_number = GetCursorNumber(conn);
    5245          80 :     initStringInfo(&sql);
    5246          80 :     appendStringInfo(&sql, "DECLARE c%u CURSOR FOR ", cursor_number);
    5247             : 
    5248          80 :     deparseAnalyzeSql(&sql, relation, method, sample_frac, &astate.retrieved_attrs);
    5249             : 
    5250             :     /* In what follows, do not risk leaking any PGresults. */
    5251          80 :     PG_TRY();
    5252             :     {
    5253             :         char        fetch_sql[64];
    5254             :         int         fetch_size;
    5255             : 
    5256          80 :         res = pgfdw_exec_query(conn, sql.data, NULL);
    5257          80 :         if (PQresultStatus(res) != PGRES_COMMAND_OK)
    5258           0 :             pgfdw_report_error(ERROR, res, conn, false, sql.data);
    5259          80 :         PQclear(res);
    5260          80 :         res = NULL;
    5261             : 
    5262             :         /*
    5263             :          * Determine the fetch size.  The default is arbitrary, but shouldn't
    5264             :          * be enormous.
    5265             :          */
    5266          80 :         fetch_size = 100;
    5267         352 :         foreach(lc, server->options)
    5268             :         {
    5269         272 :             DefElem    *def = (DefElem *) lfirst(lc);
    5270             : 
    5271         272 :             if (strcmp(def->defname, "fetch_size") == 0)
    5272             :             {
    5273           0 :                 (void) parse_int(defGetString(def), &fetch_size, 0, NULL);
    5274           0 :                 break;
    5275             :             }
    5276             :         }
    5277         186 :         foreach(lc, table->options)
    5278             :         {
    5279         106 :             DefElem    *def = (DefElem *) lfirst(lc);
    5280             : 
    5281         106 :             if (strcmp(def->defname, "fetch_size") == 0)
    5282             :             {
    5283           0 :                 (void) parse_int(defGetString(def), &fetch_size, 0, NULL);
    5284           0 :                 break;
    5285             :             }
    5286             :         }
    5287             : 
    5288             :         /* Construct command to fetch rows from remote. */
    5289          80 :         snprintf(fetch_sql, sizeof(fetch_sql), "FETCH %d FROM c%u",
    5290             :                  fetch_size, cursor_number);
    5291             : 
    5292             :         /* Retrieve and process rows a batch at a time. */
    5293             :         for (;;)
    5294         304 :         {
    5295             :             int         numrows;
    5296             :             int         i;
    5297             : 
    5298             :             /* Allow users to cancel long query */
    5299         384 :             CHECK_FOR_INTERRUPTS();
    5300             : 
    5301             :             /*
    5302             :              * XXX possible future improvement: if rowstoskip is large, we
    5303             :              * could issue a MOVE rather than physically fetching the rows,
    5304             :              * then just adjust rowstoskip and samplerows appropriately.
    5305             :              */
    5306             : 
    5307             :             /* Fetch some rows */
    5308         384 :             res = pgfdw_exec_query(conn, fetch_sql, NULL);
    5309             :             /* On error, report the original query, not the FETCH. */
    5310         384 :             if (PQresultStatus(res) != PGRES_TUPLES_OK)
    5311           0 :                 pgfdw_report_error(ERROR, res, conn, false, sql.data);
    5312             : 
    5313             :             /* Process whatever we got. */
    5314         384 :             numrows = PQntuples(res);
    5315       31832 :             for (i = 0; i < numrows; i++)
    5316       31450 :                 analyze_row_processor(res, i, &astate);
    5317             : 
    5318         382 :             PQclear(res);
    5319         382 :             res = NULL;
    5320             : 
    5321             :             /* Must be EOF if we didn't get all the rows requested. */
    5322         382 :             if (numrows < fetch_size)
    5323          78 :                 break;
    5324             :         }
    5325             : 
    5326             :         /* Close the cursor, just to be tidy. */
    5327          78 :         close_cursor(conn, cursor_number, NULL);
    5328             :     }
    5329           2 :     PG_CATCH();
    5330             :     {
    5331           2 :         PQclear(res);
    5332           2 :         PG_RE_THROW();
    5333             :     }
    5334          78 :     PG_END_TRY();
    5335             : 
    5336          78 :     ReleaseConnection(conn);
    5337             : 
    5338             :     /* We assume that we have no dead tuple. */
    5339          78 :     *totaldeadrows = 0.0;
    5340             : 
    5341             :     /*
    5342             :      * Without sampling, we've retrieved all living tuples from foreign
    5343             :      * server, so report that as totalrows.  Otherwise use the reltuples
    5344             :      * estimate we got from the remote side.
    5345             :      */
    5346          78 :     if (method == ANALYZE_SAMPLE_OFF)
    5347          78 :         *totalrows = astate.samplerows;
    5348             :     else
    5349           0 :         *totalrows = reltuples;
    5350             : 
    5351             :     /*
    5352             :      * Emit some interesting relation info
    5353             :      */
    5354          78 :     ereport(elevel,
    5355             :             (errmsg("\"%s\": table contains %.0f rows, %d rows in sample",
    5356             :                     RelationGetRelationName(relation),
    5357             :                     *totalrows, astate.numrows)));
    5358             : 
    5359          78 :     return astate.numrows;
    5360             : }
    5361             : 
    5362             : /*
    5363             :  * Collect sample rows from the result of query.
    5364             :  *   - Use all tuples in sample until target # of samples are collected.
    5365             :  *   - Subsequently, replace already-sampled tuples randomly.
    5366             :  */
    5367             : static void
    5368       31450 : analyze_row_processor(PGresult *res, int row, PgFdwAnalyzeState *astate)
    5369             : {
    5370       31450 :     int         targrows = astate->targrows;
    5371             :     int         pos;            /* array index to store tuple in */
    5372             :     MemoryContext oldcontext;
    5373             : 
    5374             :     /* Always increment sample row counter. */
    5375       31450 :     astate->samplerows += 1;
    5376             : 
    5377             :     /*
    5378             :      * Determine the slot where this sample row should be stored.  Set pos to
    5379             :      * negative value to indicate the row should be skipped.
    5380             :      */
    5381       31450 :     if (astate->numrows < targrows)
    5382             :     {
    5383             :         /* First targrows rows are always included into the sample */
    5384       31450 :         pos = astate->numrows++;
    5385             :     }
    5386             :     else
    5387             :     {
    5388             :         /*
    5389             :          * Now we start replacing tuples in the sample until we reach the end
    5390             :          * of the relation.  Same algorithm as in acquire_sample_rows in
    5391             :          * analyze.c; see Jeff Vitter's paper.
    5392             :          */
    5393           0 :         if (astate->rowstoskip < 0)
    5394           0 :             astate->rowstoskip = reservoir_get_next_S(&astate->rstate, astate->samplerows, targrows);
    5395             : 
    5396           0 :         if (astate->rowstoskip <= 0)
    5397             :         {
    5398             :             /* Choose a random reservoir element to replace. */
    5399           0 :             pos = (int) (targrows * sampler_random_fract(&astate->rstate.randstate));
    5400             :             Assert(pos >= 0 && pos < targrows);
    5401           0 :             heap_freetuple(astate->rows[pos]);
    5402             :         }
    5403             :         else
    5404             :         {
    5405             :             /* Skip this tuple. */
    5406           0 :             pos = -1;
    5407             :         }
    5408             : 
    5409           0 :         astate->rowstoskip -= 1;
    5410             :     }
    5411             : 
    5412       31450 :     if (pos >= 0)
    5413             :     {
    5414             :         /*
    5415             :          * Create sample tuple from current result row, and store it in the
    5416             :          * position determined above.  The tuple has to be created in anl_cxt.
    5417             :          */
    5418       31450 :         oldcontext = MemoryContextSwitchTo(astate->anl_cxt);
    5419             : 
    5420       31450 :         astate->rows[pos] = make_tuple_from_result_row(res, row,
    5421             :                                                        astate->rel,
    5422             :                                                        astate->attinmeta,
    5423             :                                                        astate->retrieved_attrs,
    5424             :                                                        NULL,
    5425             :                                                        astate->temp_cxt);
    5426             : 
    5427       31448 :         MemoryContextSwitchTo(oldcontext);
    5428             :     }
    5429       31448 : }
    5430             : 
    5431             : /*
    5432             :  * Import a foreign schema
    5433             :  */
    5434             : static List *
    5435          16 : postgresImportForeignSchema(ImportForeignSchemaStmt *stmt, Oid serverOid)
    5436             : {
    5437          16 :     List       *commands = NIL;
    5438          16 :     bool        import_collate = true;
    5439          16 :     bool        import_default = false;
    5440          16 :     bool        import_generated = true;
    5441          16 :     bool        import_not_null = true;
    5442             :     ForeignServer *server;
    5443             :     UserMapping *mapping;
    5444             :     PGconn     *conn;
    5445             :     StringInfoData buf;
    5446          16 :     PGresult   *volatile res = NULL;
    5447             :     int         numrows,
    5448             :                 i;
    5449             :     ListCell   *lc;
    5450             : 
    5451             :     /* Parse statement options */
    5452          24 :     foreach(lc, stmt->options)
    5453             :     {
    5454           8 :         DefElem    *def = (DefElem *) lfirst(lc);
    5455             : 
    5456           8 :         if (strcmp(def->defname, "import_collate") == 0)
    5457           2 :             import_collate = defGetBoolean(def);
    5458           6 :         else if (strcmp(def->defname, "import_default") == 0)
    5459           2 :             import_default = defGetBoolean(def);
    5460           4 :         else if (strcmp(def->defname, "import_generated") == 0)
    5461           2 :             import_generated = defGetBoolean(def);
    5462           2 :         else if (strcmp(def->defname, "import_not_null") == 0)
    5463           2 :             import_not_null = defGetBoolean(def);
    5464             :         else
    5465           0 :             ereport(ERROR,
    5466             :                     (errcode(ERRCODE_FDW_INVALID_OPTION_NAME),
    5467             :                      errmsg("invalid option \"%s\"", def->defname)));
    5468             :     }
    5469             : 
    5470             :     /*
    5471             :      * Get connection to the foreign server.  Connection manager will
    5472             :      * establish new connection if necessary.
    5473             :      */
    5474          16 :     server = GetForeignServer(serverOid);
    5475          16 :     mapping = GetUserMapping(GetUserId(), server->serverid);
    5476          16 :     conn = GetConnection(mapping, false, NULL);
    5477             : 
    5478             :     /* Don't attempt to import collation if remote server hasn't got it */
    5479          16 :     if (PQserverVersion(conn) < 90100)
    5480           0 :         import_collate = false;
    5481             : 
    5482             :     /* Create workspace for strings */
    5483          16 :     initStringInfo(&buf);
    5484             : 
    5485             :     /* In what follows, do not risk leaking any PGresults. */
    5486          16 :     PG_TRY();
    5487             :     {
    5488             :         /* Check that the schema really exists */
    5489          16 :         appendStringInfoString(&buf, "SELECT 1 FROM pg_catalog.pg_namespace WHERE nspname = ");
    5490          16 :         deparseStringLiteral(&buf, stmt->remote_schema);
    5491             : 
    5492          16 :         res = pgfdw_exec_query(conn, buf.data, NULL);
    5493          16 :         if (PQresultStatus(res) != PGRES_TUPLES_OK)
    5494           0 :             pgfdw_report_error(ERROR, res, conn, false, buf.data);
    5495             : 
    5496          16 :         if (PQntuples(res) != 1)
    5497           2 :             ereport(ERROR,
    5498             :                     (errcode(ERRCODE_FDW_SCHEMA_NOT_FOUND),
    5499             :                      errmsg("schema \"%s\" is not present on foreign server \"%s\"",
    5500             :                             stmt->remote_schema, server->servername)));
    5501             : 
    5502          14 :         PQclear(res);
    5503          14 :         res = NULL;
    5504          14 :         resetStringInfo(&buf);
    5505             : 
    5506             :         /*
    5507             :          * Fetch all table data from this schema, possibly restricted by
    5508             :          * EXCEPT or LIMIT TO.  (We don't actually need to pay any attention
    5509             :          * to EXCEPT/LIMIT TO here, because the core code will filter the
    5510             :          * statements we return according to those lists anyway.  But it
    5511             :          * should save a few cycles to not process excluded tables in the
    5512             :          * first place.)
    5513             :          *
    5514             :          * Import table data for partitions only when they are explicitly
    5515             :          * specified in LIMIT TO clause. Otherwise ignore them and only
    5516             :          * include the definitions of the root partitioned tables to allow
    5517             :          * access to the complete remote data set locally in the schema
    5518             :          * imported.
    5519             :          *
    5520             :          * Note: because we run the connection with search_path restricted to
    5521             :          * pg_catalog, the format_type() and pg_get_expr() outputs will always
    5522             :          * include a schema name for types/functions in other schemas, which
    5523             :          * is what we want.
    5524             :          */
    5525          14 :         appendStringInfoString(&buf,
    5526             :                                "SELECT relname, "
    5527             :                                "  attname, "
    5528             :                                "  format_type(atttypid, atttypmod), "
    5529             :                                "  attnotnull, "
    5530             :                                "  pg_get_expr(adbin, adrelid), ");
    5531             : 
    5532             :         /* Generated columns are supported since Postgres 12 */
    5533          14 :         if (PQserverVersion(conn) >= 120000)
    5534          14 :             appendStringInfoString(&buf,
    5535             :                                    "  attgenerated, ");
    5536             :         else
    5537           0 :             appendStringInfoString(&buf,
    5538             :                                    "  NULL, ");
    5539             : 
    5540          14 :         if (import_collate)
    5541          12 :             appendStringInfoString(&buf,
    5542             :                                    "  collname, "
    5543             :                                    "  collnsp.nspname ");
    5544             :         else
    5545           2 :             appendStringInfoString(&buf,
    5546             :                                    "  NULL, NULL ");
    5547             : 
    5548          14 :         appendStringInfoString(&buf,
    5549             :                                "FROM pg_class c "
    5550             :                                "  JOIN pg_namespace n ON "
    5551             :                                "    relnamespace = n.oid "
    5552             :                                "  LEFT JOIN pg_attribute a ON "
    5553             :                                "    attrelid = c.oid AND attnum > 0 "
    5554             :                                "      AND NOT attisdropped "
    5555             :                                "  LEFT JOIN pg_attrdef ad ON "
    5556             :                                "    adrelid = c.oid AND adnum = attnum ");
    5557             : 
    5558          14 :         if (import_collate)
    5559          12 :             appendStringInfoString(&buf,
    5560             :                                    "  LEFT JOIN pg_collation coll ON "
    5561             :                                    "    coll.oid = attcollation "
    5562             :                                    "  LEFT JOIN pg_namespace collnsp ON "
    5563             :                                    "    collnsp.oid = collnamespace ");
    5564             : 
    5565          14 :         appendStringInfoString(&buf,
    5566             :                                "WHERE c.relkind IN ("
    5567             :                                CppAsString2(RELKIND_RELATION) ","
    5568             :                                CppAsString2(RELKIND_VIEW) ","
    5569             :                                CppAsString2(RELKIND_FOREIGN_TABLE) ","
    5570             :                                CppAsString2(RELKIND_MATVIEW) ","
    5571             :                                CppAsString2(RELKIND_PARTITIONED_TABLE) ") "
    5572             :                                "  AND n.nspname = ");
    5573          14 :         deparseStringLiteral(&buf, stmt->remote_schema);
    5574             : 
    5575             :         /* Partitions are supported since Postgres 10 */
    5576          14 :         if (PQserverVersion(conn) >= 100000 &&
    5577          14 :             stmt->list_type != FDW_IMPORT_SCHEMA_LIMIT_TO)
    5578          10 :             appendStringInfoString(&buf, " AND NOT c.relispartition ");
    5579             : 
    5580             :         /* Apply restrictions for LIMIT TO and EXCEPT */
    5581          14 :         if (stmt->list_type == FDW_IMPORT_SCHEMA_LIMIT_TO ||
    5582          10 :             stmt->list_type == FDW_IMPORT_SCHEMA_EXCEPT)
    5583             :         {
    5584           6 :             bool        first_item = true;
    5585             : 
    5586           6 :             appendStringInfoString(&buf, " AND c.relname ");
    5587           6 :             if (stmt->list_type == FDW_IMPORT_SCHEMA_EXCEPT)
    5588           2 :                 appendStringInfoString(&buf, "NOT ");
    5589           6 :             appendStringInfoString(&buf, "IN (");
    5590             : 
    5591             :             /* Append list of table names within IN clause */
    5592          22 :             foreach(lc, stmt->table_list)
    5593             :             {
    5594          16 :                 RangeVar   *rv = (RangeVar *) lfirst(lc);
    5595             : 
    5596          16 :                 if (first_item)
    5597           6 :                     first_item = false;
    5598             :                 else
    5599          10 :                     appendStringInfoString(&buf, ", ");
    5600          16 :                 deparseStringLiteral(&buf, rv->relname);
    5601             :             }
    5602           6 :             appendStringInfoChar(&buf, ')');
    5603             :         }
    5604             : 
    5605             :         /* Append ORDER BY at the end of query to ensure output ordering */
    5606          14 :         appendStringInfoString(&buf, " ORDER BY c.relname, a.attnum");
    5607             : 
    5608             :         /* Fetch the data */
    5609          14 :         res = pgfdw_exec_query(conn, buf.data, NULL);
    5610          14 :         if (PQresultStatus(res) != PGRES_TUPLES_OK)
    5611           0 :             pgfdw_report_error(ERROR, res, conn, false, buf.data);
    5612             : 
    5613             :         /* Process results */
    5614          14 :         numrows = PQntuples(res);
    5615             :         /* note: incrementation of i happens in inner loop's while() test */
    5616          86 :         for (i = 0; i < numrows;)
    5617             :         {
    5618          72 :             char       *tablename = PQgetvalue(res, i, 0);
    5619          72 :             bool        first_item = true;
    5620             : 
    5621          72 :             resetStringInfo(&buf);
    5622          72 :             appendStringInfo(&buf, "CREATE FOREIGN TABLE %s (\n",
    5623             :                              quote_identifier(tablename));
    5624             : 
    5625             :             /* Scan all rows for this table */
    5626             :             do
    5627             :             {
    5628             :                 char       *attname;
    5629             :                 char       *typename;
    5630             :                 char       *attnotnull;
    5631             :                 char       *attgenerated;
    5632             :                 char       *attdefault;
    5633             :                 char       *collname;
    5634             :                 char       *collnamespace;
    5635             : 
    5636             :                 /* If table has no columns, we'll see nulls here */
    5637         142 :                 if (PQgetisnull(res, i, 1))
    5638          10 :                     continue;
    5639             : 
    5640         132 :                 attname = PQgetvalue(res, i, 1);
    5641         132 :                 typename = PQgetvalue(res, i, 2);
    5642         132 :                 attnotnull = PQgetvalue(res, i, 3);
    5643         132 :                 attdefault = PQgetisnull(res, i, 4) ? (char *) NULL :
    5644          30 :                     PQgetvalue(res, i, 4);
    5645         132 :                 attgenerated = PQgetisnull(res, i, 5) ? (char *) NULL :
    5646         132 :                     PQgetvalue(res, i, 5);
    5647         132 :                 collname = PQgetisnull(res, i, 6) ? (char *) NULL :
    5648          38 :                     PQgetvalue(res, i, 6);
    5649         132 :                 collnamespace = PQgetisnull(res, i, 7) ? (char *) NULL :
    5650          38 :                     PQgetvalue(res, i, 7);
    5651             : 
    5652         132 :                 if (first_item)
    5653          62 :                     first_item = false;
    5654             :                 else
    5655          70 :                     appendStringInfoString(&buf, ",\n");
    5656             : 
    5657             :                 /* Print column name and type */
    5658         132 :                 appendStringInfo(&buf, "  %s %s",
    5659             :                                  quote_identifier(attname),
    5660             :                                  typename);
    5661             : 
    5662             :                 /*
    5663             :                  * Add column_name option so that renaming the foreign table's
    5664             :                  * column doesn't break the association to the underlying
    5665             :                  * column.
    5666             :                  */
    5667         132 :                 appendStringInfoString(&buf, " OPTIONS (column_name ");
    5668         132 :                 deparseStringLiteral(&buf, attname);
    5669         132 :                 appendStringInfoChar(&buf, ')');
    5670             : 
    5671             :                 /* Add COLLATE if needed */
    5672         132 :                 if (import_collate && collname != NULL && collnamespace != NULL)
    5673          38 :                     appendStringInfo(&buf, " COLLATE %s.%s",
    5674             :                                      quote_identifier(collnamespace),
    5675             :                                      quote_identifier(collname));
    5676             : 
    5677             :                 /* Add DEFAULT if needed */
    5678         132 :                 if (import_default && attdefault != NULL &&
    5679           6 :                     (!attgenerated || !attgenerated[0]))
    5680           4 :                     appendStringInfo(&buf, " DEFAULT %s", attdefault);
    5681             : 
    5682             :                 /* Add GENERATED if needed */
    5683         132 :                 if (import_generated && attgenerated != NULL &&
    5684         106 :                     attgenerated[0] == ATTRIBUTE_GENERATED_STORED)
    5685             :                 {
    5686             :                     Assert(attdefault != NULL);
    5687           8 :                     appendStringInfo(&buf,
    5688             :                                      " GENERATED ALWAYS AS (%s) STORED",
    5689             :                                      attdefault);
    5690             :                 }
    5691             : 
    5692             :                 /* Add NOT NULL if needed */
    5693         132 :                 if (import_not_null && attnotnull[0] == 't')
    5694           8 :                     appendStringInfoString(&buf, " NOT NULL");
    5695             :             }
    5696         128 :             while (++i < numrows &&
    5697         142 :                    strcmp(PQgetvalue(res, i, 0), tablename) == 0);
    5698             : 
    5699             :             /*
    5700             :              * Add server name and table-level options.  We specify remote
    5701             :              * schema and table name as options (the latter to ensure that
    5702             :              * renaming the foreign table doesn't break the association).
    5703             :              */
    5704          72 :             appendStringInfo(&buf, "\n) SERVER %s\nOPTIONS (",
    5705          72 :                              quote_identifier(server->servername));
    5706             : 
    5707          72 :             appendStringInfoString(&buf, "schema_name ");
    5708          72 :             deparseStringLiteral(&buf, stmt->remote_schema);
    5709          72 :             appendStringInfoString(&buf, ", table_name ");
    5710          72 :             deparseStringLiteral(&buf, tablename);
    5711             : 
    5712          72 :             appendStringInfoString(&buf, ");");
    5713             : 
    5714          72 :             commands = lappend(commands, pstrdup(buf.data));
    5715             :         }
    5716             :     }
    5717           2 :     PG_FINALLY();
    5718             :     {
    5719          16 :         PQclear(res);
    5720             :     }
    5721          16 :     PG_END_TRY();
    5722             : 
    5723          14 :     ReleaseConnection(conn);
    5724             : 
    5725          14 :     return commands;
    5726             : }
    5727             : 
    5728             : /*
    5729             :  * Check if reltarget is safe enough to push down semi-join.  Reltarget is not
    5730             :  * safe, if it contains references to inner rel relids, which do not belong to
    5731             :  * outer rel.
    5732             :  */
    5733             : static bool
    5734         116 : semijoin_target_ok(PlannerInfo *root, RelOptInfo *joinrel, RelOptInfo *outerrel, RelOptInfo *innerrel)
    5735             : {
    5736             :     List       *vars;
    5737             :     ListCell   *lc;
    5738         116 :     bool        ok = true;
    5739             : 
    5740             :     Assert(joinrel->reltarget);
    5741             : 
    5742         116 :     vars = pull_var_clause((Node *) joinrel->reltarget->exprs, PVC_INCLUDE_PLACEHOLDERS);
    5743             : 
    5744         862 :     foreach(lc, vars)
    5745             :     {
    5746         776 :         Var        *var = (Var *) lfirst(lc);
    5747             : 
    5748         776 :         if (!IsA(var, Var))
    5749           0 :             continue;
    5750             : 
    5751         776 :         if (bms_is_member(var->varno, innerrel->relids) &&
    5752          30 :             !bms_is_member(var->varno, outerrel->relids))
    5753             :         {
    5754             :             /*
    5755             :              * The planner can create semi-join, which refers to inner rel
    5756             :              * vars in its target list. However, we deparse semi-join as an
    5757             :              * exists() subquery, so can't handle references to inner rel in
    5758             :              * the target list.
    5759             :              */
    5760          30 :             ok = false;
    5761          30 :             break;
    5762             :         }
    5763             :     }
    5764         116 :     return ok;
    5765             : }
    5766             : 
    5767             : /*
    5768             :  * Assess whether the join between inner and outer relations can be pushed down
    5769             :  * to the foreign server. As a side effect, save information we obtain in this
    5770             :  * function to PgFdwRelationInfo passed in.
    5771             :  */
    5772             : static bool
    5773         736 : foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
    5774             :                 RelOptInfo *outerrel, RelOptInfo *innerrel,
    5775             :                 JoinPathExtraData *extra)
    5776             : {
    5777             :     PgFdwRelationInfo *fpinfo;
    5778             :     PgFdwRelationInfo *fpinfo_o;
    5779             :     PgFdwRelationInfo *fpinfo_i;
    5780             :     ListCell   *lc;
    5781             :     List       *joinclauses;
    5782             : 
    5783             :     /*
    5784             :      * We support pushing down INNER, LEFT, RIGHT, FULL OUTER and SEMI joins.
    5785             :      * Constructing queries representing ANTI joins is hard, hence not
    5786             :      * considered right now.
    5787             :      */
    5788         736 :     if (jointype != JOIN_INNER && jointype != JOIN_LEFT &&
    5789         246 :         jointype != JOIN_RIGHT && jointype != JOIN_FULL &&
    5790             :         jointype != JOIN_SEMI)
    5791          38 :         return false;
    5792             : 
    5793             :     /*
    5794             :      * We can't push down semi-join if its reltarget is not safe
    5795             :      */
    5796         698 :     if ((jointype == JOIN_SEMI) && !semijoin_target_ok(root, joinrel, outerrel, innerrel))
    5797          30 :         return false;
    5798             : 
    5799             :     /*
    5800             :      * If either of the joining relations is marked as unsafe to pushdown, the
    5801             :      * join can not be pushed down.
    5802             :      */
    5803         668 :     fpinfo = (PgFdwRelationInfo *) joinrel->fdw_private;
    5804         668 :     fpinfo_o = (PgFdwRelationInfo *) outerrel->fdw_private;
    5805         668 :     fpinfo_i = (PgFdwRelationInfo *) innerrel->fdw_private;
    5806         668 :     if (!fpinfo_o || !fpinfo_o->pushdown_safe ||
    5807         658 :         !fpinfo_i || !fpinfo_i->pushdown_safe)
    5808          10 :         return false;
    5809             : 
    5810             :     /*
    5811             :      * If joining relations have local conditions, those conditions are
    5812             :      * required to be applied before joining the relations. Hence the join can
    5813             :      * not be pushed down.
    5814             :      */
    5815         658 :     if (fpinfo_o->local_conds || fpinfo_i->local_conds)
    5816          18 :         return false;
    5817             : 
    5818             :     /*
    5819             :      * Merge FDW options.  We might be tempted to do this after we have deemed
    5820             :      * the foreign join to be OK.  But we must do this beforehand so that we
    5821             :      * know which quals can be evaluated on the foreign server, which might
    5822             :      * depend on shippable_extensions.
    5823             :      */
    5824         640 :     fpinfo->server = fpinfo_o->server;
    5825         640 :     merge_fdw_options(fpinfo, fpinfo_o, fpinfo_i);
    5826             : 
    5827             :     /*
    5828             :      * Separate restrict list into join quals and pushed-down (other) quals.
    5829             :      *
    5830             :      * Join quals belonging to an outer join must all be shippable, else we
    5831             :      * cannot execute the join remotely.  Add such quals to 'joinclauses'.
    5832             :      *
    5833             :      * Add other quals to fpinfo->remote_conds if they are shippable, else to
    5834             :      * fpinfo->local_conds.  In an inner join it's okay to execute conditions
    5835             :      * either locally or remotely; the same is true for pushed-down conditions
    5836             :      * at an outer join.
    5837             :      *
    5838             :      * Note we might return failure after having already scribbled on
    5839             :      * fpinfo->remote_conds and fpinfo->local_conds.  That's okay because we
    5840             :      * won't consult those lists again if we deem the join unshippable.
    5841             :      */
    5842         640 :     joinclauses = NIL;
    5843        1274 :     foreach(lc, extra->restrictlist)
    5844             :     {
    5845         640 :         RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
    5846         640 :         bool        is_remote_clause = is_foreign_expr(root, joinrel,
    5847             :                                                        rinfo->clause);
    5848             : 
    5849         640 :         if (IS_OUTER_JOIN(jointype) &&
    5850         254 :             !RINFO_IS_PUSHED_DOWN(rinfo, joinrel->relids))
    5851             :         {
    5852         222 :             if (!is_remote_clause)
    5853           6 :                 return false;
    5854         216 :             joinclauses = lappend(joinclauses, rinfo);
    5855             :         }
    5856             :         else
    5857             :         {
    5858         418 :             if (is_remote_clause)
    5859         394 :                 fpinfo->remote_conds = lappend(fpinfo->remote_conds, rinfo);
    5860             :             else
    5861          24 :                 fpinfo->local_conds = lappend(fpinfo->local_conds, rinfo);
    5862             :         }
    5863             :     }
    5864             : 
    5865             :     /*
    5866             :      * deparseExplicitTargetList() isn't smart enough to handle anything other
    5867             :      * than a Var.  In particular, if there's some PlaceHolderVar that would
    5868             :      * need to be evaluated within this join tree (because there's an upper
    5869             :      * reference to a quantity that may go to NULL as a result of an outer
    5870             :      * join), then we can't try to push the join down because we'll fail when
    5871             :      * we get to deparseExplicitTargetList().  However, a PlaceHolderVar that
    5872             :      * needs to be evaluated *at the top* of this join tree is OK, because we
    5873             :      * can do that locally after fetching the results from the remote side.
    5874             :      */
    5875         640 :     foreach(lc, root->placeholder_list)
    5876             :     {
    5877          22 :         PlaceHolderInfo *phinfo = lfirst(lc);
    5878             :         Relids      relids;
    5879             : 
    5880             :         /* PlaceHolderInfo refers to parent relids, not child relids. */
    5881          22 :         relids = IS_OTHER_REL(joinrel) ?
    5882          44 :             joinrel->top_parent_relids : joinrel->relids;
    5883             : 
    5884          44 :         if (bms_is_subset(phinfo->ph_eval_at, relids) &&
    5885          22 :             bms_nonempty_difference(relids, phinfo->ph_eval_at))
    5886          16 :             return false;
    5887             :     }
    5888             : 
    5889             :     /* Save the join clauses, for later use. */
    5890         618 :     fpinfo->joinclauses = joinclauses;
    5891             : 
    5892         618 :     fpinfo->outerrel = outerrel;
    5893         618 :     fpinfo->innerrel = innerrel;
    5894         618 :     fpinfo->jointype = jointype;
    5895             : 
    5896             :     /*
    5897             :      * By default, both the input relations are not required to be deparsed as
    5898             :      * subqueries, but there might be some relations covered by the input
    5899             :      * relations that are required to be deparsed as subqueries, so save the
    5900             :      * relids of those relations for later use by the deparser.
    5901             :      */
    5902         618 :     fpinfo->make_outerrel_subquery = false;
    5903         618 :     fpinfo->make_innerrel_subquery = false;
    5904             :     Assert(bms_is_subset(fpinfo_o->lower_subquery_rels, outerrel->relids));
    5905             :     Assert(bms_is_subset(fpinfo_i->lower_subquery_rels, innerrel->relids));
    5906        1236 :     fpinfo->lower_subquery_rels = bms_union(fpinfo_o->lower_subquery_rels,
    5907         618 :                                             fpinfo_i->lower_subquery_rels);
    5908        1236 :     fpinfo->hidden_subquery_rels = bms_union(fpinfo_o->hidden_subquery_rels,
    5909         618 :                                              fpinfo_i->hidden_subquery_rels);
    5910             : 
    5911             :     /*
    5912             :      * Pull the other remote conditions from the joining relations into join
    5913             :      * clauses or other remote clauses (remote_conds) of this relation
    5914             :      * wherever possible. This avoids building subqueries at every join step.
    5915             :      *
    5916             :      * For an inner join, clauses from both the relations are added to the
    5917             :      * other remote clauses. For LEFT and RIGHT OUTER join, the clauses from
    5918             :      * the outer side are added to remote_conds since those can be evaluated
    5919             :      * after the join is evaluated. The clauses from inner side are added to
    5920             :      * the joinclauses, since they need to be evaluated while constructing the
    5921             :      * join.
    5922             :      *
    5923             :      * For SEMI-JOIN clauses from inner relation can not be added to
    5924             :      * remote_conds, but should be treated as join clauses (as they are
    5925             :      * deparsed to EXISTS subquery, where inner relation can be referred). A
    5926             :      * list of relation ids, which can't be referred to from higher levels, is
    5927             :      * preserved as a hidden_subquery_rels list.
    5928             :      *
    5929             :      * For a FULL OUTER JOIN, the other clauses from either relation can not
    5930             :      * be added to the joinclauses or remote_conds, since each relation acts
    5931             :      * as an outer relation for the other.
    5932             :      *
    5933             :      * The joining sides can not have local conditions, thus no need to test
    5934             :      * shippability of the clauses being pulled up.
    5935             :      */
    5936         618 :     switch (jointype)
    5937             :     {
    5938         342 :         case JOIN_INNER:
    5939         684 :             fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
    5940         342 :                                                fpinfo_i->remote_conds);
    5941         684 :             fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
    5942         342 :                                                fpinfo_o->remote_conds);
    5943         342 :             break;
    5944             : 
    5945         116 :         case JOIN_LEFT:
    5946         232 :             fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
    5947         116 :                                               fpinfo_i->remote_conds);
    5948         232 :             fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
    5949         116 :                                                fpinfo_o->remote_conds);
    5950         116 :             break;
    5951             : 
    5952           0 :         case JOIN_RIGHT:
    5953           0 :             fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
    5954           0 :                                               fpinfo_o->remote_conds);
    5955           0 :             fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
    5956           0 :                                                fpinfo_i->remote_conds);
    5957           0 :             break;
    5958             : 
    5959          76 :         case JOIN_SEMI:
    5960         152 :             fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
    5961          76 :                                               fpinfo_i->remote_conds);
    5962         152 :             fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
    5963          76 :                                               fpinfo->remote_conds);
    5964          76 :             fpinfo->remote_conds = list_copy(fpinfo_o->remote_conds);
    5965         152 :             fpinfo->hidden_subquery_rels = bms_union(fpinfo->hidden_subquery_rels,
    5966          76 :                                                      innerrel->relids);
    5967          76 :             break;
    5968             : 
    5969          84 :         case JOIN_FULL:
    5970             : 
    5971             :             /*
    5972             :              * In this case, if any of the input relations has conditions, we
    5973             :              * need to deparse that relation as a subquery so that the
    5974             :              * conditions can be evaluated before the join.  Remember it in
    5975             :              * the fpinfo of this relation so that the deparser can take
    5976             :              * appropriate action.  Also, save the relids of base relations
    5977             :              * covered by that relation for later use by the deparser.
    5978             :              */
    5979          84 :             if (fpinfo_o->remote_conds)
    5980             :             {
    5981          28 :                 fpinfo->make_outerrel_subquery = true;
    5982          28 :                 fpinfo->lower_subquery_rels =
    5983          28 :                     bms_add_members(fpinfo->lower_subquery_rels,
    5984          28 :                                     outerrel->relids);
    5985             :             }
    5986          84 :             if (fpinfo_i->remote_conds)
    5987             :             {
    5988          28 :                 fpinfo->make_innerrel_subquery = true;
    5989          28 :                 fpinfo->lower_subquery_rels =
    5990          28 :                     bms_add_members(fpinfo->lower_subquery_rels,
    5991          28 :                                     innerrel->relids);
    5992             :             }
    5993          84 :             break;
    5994             : 
    5995           0 :         default:
    5996             :             /* Should not happen, we have just checked this above */
    5997           0 :             elog(ERROR, "unsupported join type %d", jointype);
    5998             :     }
    5999             : 
    6000             :     /*
    6001             :      * For an inner join, all restrictions can be treated alike. Treating the
    6002             :      * pushed down conditions as join conditions allows a top level full outer
    6003             :      * join to be deparsed without requiring subqueries.
    6004             :      */
    6005         618 :     if (jointype == JOIN_INNER)
    6006             :     {
    6007             :         Assert(!fpinfo->joinclauses);
    6008         342 :         fpinfo->joinclauses = fpinfo->remote_conds;
    6009         342 :         fpinfo->remote_conds = NIL;
    6010             :     }
    6011         276 :     else if (jointype == JOIN_LEFT || jointype == JOIN_RIGHT || jointype == JOIN_FULL)
    6012             :     {
    6013             :         /*
    6014             :          * Conditions, generated from semi-joins, should be evaluated before
    6015             :          * LEFT/RIGHT/FULL join.
    6016             :          */
    6017         200 :         if (!bms_is_empty(fpinfo_o->hidden_subquery_rels))
    6018             :         {
    6019           0 :             fpinfo->make_outerrel_subquery = true;
    6020           0 :             fpinfo->lower_subquery_rels = bms_add_members(fpinfo->lower_subquery_rels, outerrel->relids);
    6021             :         }
    6022             : 
    6023         200 :         if (!bms_is_empty(fpinfo_i->hidden_subquery_rels))
    6024             :         {
    6025           4 :             fpinfo->make_innerrel_subquery = true;
    6026           4 :             fpinfo->lower_subquery_rels = bms_add_members(fpinfo->lower_subquery_rels, innerrel->relids);
    6027             :         }
    6028             :     }
    6029             : 
    6030             :     /* Mark that this join can be pushed down safely */
    6031         618 :     fpinfo->pushdown_safe = true;
    6032             : 
    6033             :     /* Get user mapping */
    6034         618 :     if (fpinfo->use_remote_estimate)
    6035             :     {
    6036         442 :         if (fpinfo_o->use_remote_estimate)
    6037         306 :             fpinfo->user = fpinfo_o->user;
    6038             :         else
    6039         136 :             fpinfo->user = fpinfo_i->user;
    6040             :     }
    6041             :     else
    6042         176 :         fpinfo->user = NULL;
    6043             : 
    6044             :     /*
    6045             :      * Set # of retrieved rows and cached relation costs to some negative
    6046             :      * value, so that we can detect when they are set to some sensible values,
    6047             :      * during one (usually the first) of the calls to estimate_path_cost_size.
    6048             :      */
    6049         618 :     fpinfo->retrieved_rows = -1;
    6050         618 :     fpinfo->rel_startup_cost = -1;
    6051         618 :     fpinfo->rel_total_cost = -1;
    6052             : 
    6053             :     /*
    6054             :      * Set the string describing this join relation to be used in EXPLAIN
    6055             :      * output of corresponding ForeignScan.  Note that the decoration we add
    6056             :      * to the base relation names mustn't include any digits, or it'll confuse
    6057             :      * postgresExplainForeignScan.
    6058             :      */
    6059         618 :     fpinfo->relation_name = psprintf("(%s) %s JOIN (%s)",
    6060             :                                      fpinfo_o->relation_name,
    6061             :                                      get_jointype_name(fpinfo->jointype),
    6062             :                                      fpinfo_i->relation_name);
    6063             : 
    6064             :     /*
    6065             :      * Set the relation index.  This is defined as the position of this
    6066             :      * joinrel in the join_rel_list list plus the length of the rtable list.
    6067             :      * Note that since this joinrel is at the end of the join_rel_list list
    6068             :      * when we are called, we can get the position by list_length.
    6069             :      */
    6070             :     Assert(fpinfo->relation_index == 0); /* shouldn't be set yet */
    6071         618 :     fpinfo->relation_index =
    6072         618 :         list_length(root->parse->rtable) + list_length(root->join_rel_list);
    6073             : 
    6074         618 :     return true;
    6075             : }
    6076             : 
    6077             : static void
    6078        2890 : add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel,
    6079             :                                 Path *epq_path, List *restrictlist)
    6080             : {
    6081        2890 :     List       *useful_pathkeys_list = NIL; /* List of all pathkeys */
    6082             :     ListCell   *lc;
    6083             : 
    6084        2890 :     useful_pathkeys_list = get_useful_pathkeys_for_relation(root, rel);
    6085             : 
    6086             :     /*
    6087             :      * Before creating sorted paths, arrange for the passed-in EPQ path, if
    6088             :      * any, to return columns needed by the parent ForeignScan node so that
    6089             :      * they will propagate up through Sort nodes injected below, if necessary.
    6090             :      */
    6091        2890 :     if (epq_path != NULL && useful_pathkeys_list != NIL)
    6092             :     {
    6093          56 :         PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) rel->fdw_private;
    6094          56 :         PathTarget *target = copy_pathtarget(epq_path->pathtarget);
    6095             : 
    6096             :         /* Include columns required for evaluating PHVs in the tlist. */
    6097          56 :         add_new_columns_to_pathtarget(target,
    6098          56 :                                       pull_var_clause((Node *) target->exprs,
    6099             :                                                       PVC_RECURSE_PLACEHOLDERS));
    6100             : 
    6101             :         /* Include columns required for evaluating the local conditions. */
    6102          62 :         foreach(lc, fpinfo->local_conds)
    6103             :         {
    6104           6 :             RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
    6105             : 
    6106           6 :             add_new_columns_to_pathtarget(target,
    6107           6 :                                           pull_var_clause((Node *) rinfo->clause,
    6108             :                                                           PVC_RECURSE_PLACEHOLDERS));
    6109             :         }
    6110             : 
    6111             :         /*
    6112             :          * If we have added any new columns, adjust the tlist of the EPQ path.
    6113             :          *
    6114             :          * Note: the plan created using this path will only be used to execute
    6115             :          * EPQ checks, where accuracy of the plan cost and width estimates
    6116             :          * would not be important, so we do not do set_pathtarget_cost_width()
    6117             :          * for the new pathtarget here.  See also postgresGetForeignPlan().
    6118             :          */
    6119          56 :         if (list_length(target->exprs) > list_length(epq_path->pathtarget->exprs))
    6120             :         {
    6121             :             /* The EPQ path is a join path, so it is projection-capable. */
    6122             :             Assert(is_projection_capable_path(epq_path));
    6123             : 
    6124             :             /*
    6125             :              * Use create_projection_path() here, so as to avoid modifying it
    6126             :              * in place.
    6127             :              */
    6128           8 :             epq_path = (Path *) create_projection_path(root,
    6129             :                                                        rel,
    6130             :                                                        epq_path,
    6131             :                                                        target);
    6132             :         }
    6133             :     }
    6134             : 
    6135             :     /* Create one path for each set of pathkeys we found above. */
    6136        4226 :     foreach(lc, useful_pathkeys_list)
    6137             :     {
    6138             :         double      rows;
    6139             :         int         width;
    6140             :         Cost        startup_cost;
    6141             :         Cost        total_cost;
    6142        1336 :         List       *useful_pathkeys = lfirst(lc);
    6143             :         Path       *sorted_epq_path;
    6144             : 
    6145        1336 :         estimate_path_cost_size(root, rel, NIL, useful_pathkeys, NULL,
    6146             :                                 &rows, &width, &startup_cost, &total_cost);
    6147             : 
    6148             :         /*
    6149             :          * The EPQ path must be at least as well sorted as the path itself, in
    6150             :          * case it gets used as input to a mergejoin.
    6151             :          */
    6152        1336 :         sorted_epq_path = epq_path;
    6153        1336 :         if (sorted_epq_path != NULL &&
    6154          56 :             !pathkeys_contained_in(useful_pathkeys,
    6155             :                                    sorted_epq_path->pathkeys))
    6156             :             sorted_epq_path = (Path *)
    6157          44 :                 create_sort_path(root,
    6158             :                                  rel,
    6159             :                                  sorted_epq_path,
    6160             :                                  useful_pathkeys,
    6161             :                                  -1.0);
    6162             : 
    6163        1336 :         if (IS_SIMPLE_REL(rel))
    6164         830 :             add_path(rel, (Path *)
    6165         830 :                      create_foreignscan_path(root, rel,
    6166             :                                              NULL,
    6167             :                                              rows,
    6168             :                                              startup_cost,
    6169             :                                              total_cost,
    6170             :                                              useful_pathkeys,
    6171             :                                              rel->lateral_relids,
    6172             :                                              sorted_epq_path,
    6173             :                                              NIL,   /* no fdw_restrictinfo
    6174             :                                                      * list */
    6175             :                                              NIL));
    6176             :         else
    6177         506 :             add_path(rel, (Path *)
    6178         506 :                      create_foreign_join_path(root, rel,
    6179             :                                               NULL,
    6180             :                                               rows,
    6181             :                                               startup_cost,
    6182             :                                               total_cost,
    6183             :                                               useful_pathkeys,
    6184             :                                               rel->lateral_relids,
    6185             :                                               sorted_epq_path,
    6186             :                                               restrictlist,
    6187             :                                               NIL));
    6188             :     }
    6189        2890 : }
    6190             : 
    6191             : /*
    6192             :  * Parse options from foreign server and apply them to fpinfo.
    6193             :  *
    6194             :  * New options might also require tweaking merge_fdw_options().
    6195             :  */
    6196             : static void
    6197        2276 : apply_server_options(PgFdwRelationInfo *fpinfo)
    6198             : {
    6199             :     ListCell   *lc;
    6200             : 
    6201        9556 :     foreach(lc, fpinfo->server->options)
    6202             :     {
    6203        7280 :         DefElem    *def = (DefElem *) lfirst(lc);
    6204             : 
    6205        7280 :         if (strcmp(def->defname, "use_remote_estimate") == 0)
    6206         188 :             fpinfo->use_remote_estimate = defGetBoolean(def);
    6207        7092 :         else if (strcmp(def->defname, "fdw_startup_cost") == 0)
    6208          12 :             (void) parse_real(defGetString(def), &fpinfo->fdw_startup_cost, 0,
    6209             :                               NULL);
    6210        7080 :         else if (strcmp(def->defname, "fdw_tuple_cost") == 0)
    6211           4 :             (void) parse_real(defGetString(def), &fpinfo->fdw_tuple_cost, 0,
    6212             :                               NULL);
    6213        7076 :         else if (strcmp(def->defname, "extensions") == 0)
    6214        1798 :             fpinfo->shippable_extensions =
    6215        1798 :                 ExtractExtensionList(defGetString(def), false);
    6216        5278 :         else if (strcmp(def->defname, "fetch_size") == 0)
    6217           0 :             (void) parse_int(defGetString(def), &fpinfo->fetch_size, 0, NULL);
    6218        5278 :         else if (strcmp(def->defname, "async_capable") == 0)
    6219         242 :             fpinfo->async_capable = defGetBoolean(def);
    6220             :     }
    6221        2276 : }
    6222             : 
    6223             : /*
    6224             :  * Parse options from foreign table and apply them to fpinfo.
    6225             :  *
    6226             :  * New options might also require tweaking merge_fdw_options().
    6227             :  */
    6228             : static void
    6229        2276 : apply_table_options(PgFdwRelationInfo *fpinfo)
    6230             : {
    6231             :     ListCell   *lc;
    6232             : 
    6233        6628 :     foreach(lc, fpinfo->table->options)
    6234             :     {
    6235        4352 :         DefElem    *def = (DefElem *) lfirst(lc);
    6236             : 
    6237        4352 :         if (strcmp(def->defname, "use_remote_estimate") == 0)
    6238         666 :             fpinfo->use_remote_estimate = defGetBoolean(def);
    6239        3686 :         else if (strcmp(def->defname, "fetch_size") == 0)
    6240           0 :             (void) parse_int(defGetString(def), &fpinfo->fetch_size, 0, NULL);
    6241        3686 :         else if (strcmp(def->defname, "async_capable") == 0)
    6242           0 :             fpinfo->async_capable = defGetBoolean(def);
    6243             :     }
    6244        2276 : }
    6245             : 
    6246             : /*
    6247             :  * Merge FDW options from input relations into a new set of options for a join
    6248             :  * or an upper rel.
    6249             :  *
    6250             :  * For a join relation, FDW-specific information about the inner and outer
    6251             :  * relations is provided using fpinfo_i and fpinfo_o.  For an upper relation,
    6252             :  * fpinfo_o provides the information for the input relation; fpinfo_i is
    6253             :  * expected to NULL.
    6254             :  */
    6255             : static void
    6256        1504 : merge_fdw_options(PgFdwRelationInfo *fpinfo,
    6257             :                   const PgFdwRelationInfo *fpinfo_o,
    6258             :                   const PgFdwRelationInfo *fpinfo_i)
    6259             : {
    6260             :     /* We must always have fpinfo_o. */
    6261             :     Assert(fpinfo_o);
    6262             : 
    6263             :     /* fpinfo_i may be NULL, but if present the servers must both match. */
    6264             :     Assert(!fpinfo_i ||
    6265             :            fpinfo_i->server->serverid == fpinfo_o->server->serverid);
    6266             : 
    6267             :     /*
    6268             :      * Copy the server specific FDW options.  (For a join, both relations come
    6269             :      * from the same server, so the server options should have the same value
    6270             :      * for both relations.)
    6271             :      */
    6272        1504 :     fpinfo->fdw_startup_cost = fpinfo_o->fdw_startup_cost;
    6273        1504 :     fpinfo->fdw_tuple_cost = fpinfo_o->fdw_tuple_cost;
    6274        1504 :     fpinfo->shippable_extensions = fpinfo_o->shippable_extensions;
    6275        1504 :     fpinfo->use_remote_estimate = fpinfo_o->use_remote_estimate;
    6276        1504 :     fpinfo->fetch_size = fpinfo_o->fetch_size;
    6277        1504 :     fpinfo->async_capable = fpinfo_o->async_capable;
    6278             : 
    6279             :     /* Merge the table level options from either side of the join. */
    6280        1504 :     if (fpinfo_i)
    6281             :     {
    6282             :         /*
    6283             :          * We'll prefer to use remote estimates for this join if any table
    6284             :          * from either side of the join is using remote estimates.  This is
    6285             :          * most likely going to be preferred since they're already willing to
    6286             :          * pay the price of a round trip to get the remote EXPLAIN.  In any
    6287             :          * case it's not entirely clear how we might otherwise handle this
    6288             :          * best.
    6289             :          */
    6290         964 :         fpinfo->use_remote_estimate = fpinfo_o->use_remote_estimate ||
    6291         324 :             fpinfo_i->use_remote_estimate;
    6292             : 
    6293             :         /*
    6294             :          * Set fetch size to maximum of the joining sides, since we are
    6295             :          * expecting the rows returned by the join to be proportional to the
    6296             :          * relation sizes.
    6297             :          */
    6298         640 :         fpinfo->fetch_size = Max(fpinfo_o->fetch_size, fpinfo_i->fetch_size);
    6299             : 
    6300             :         /*
    6301             :          * We'll prefer to consider this join async-capable if any table from
    6302             :          * either side of the join is considered async-capable.  This would be
    6303             :          * reasonable because in that case the foreign server would have its
    6304             :          * own resources to scan that table asynchronously, and the join could
    6305             :          * also be computed asynchronously using the resources.
    6306             :          */
    6307        1264 :         fpinfo->async_capable = fpinfo_o->async_capable ||
    6308         624 :             fpinfo_i->async_capable;
    6309             :     }
    6310        1504 : }
    6311             : 
    6312             : /*
    6313             :  * postgresGetForeignJoinPaths
    6314             :  *      Add possible ForeignPath to joinrel, if join is safe to push down.
    6315             :  */
    6316             : static void
    6317        2394 : postgresGetForeignJoinPaths(PlannerInfo *root,
    6318             :                             RelOptInfo *joinrel,
    6319             :                             RelOptInfo *outerrel,
    6320             :                             RelOptInfo *innerrel,
    6321             :                             JoinType jointype,
    6322             :                             JoinPathExtraData *extra)
    6323             : {
    6324             :     PgFdwRelationInfo *fpinfo;
    6325             :     ForeignPath *joinpath;
    6326             :     double      rows;
    6327             :     int         width;
    6328             :     Cost        startup_cost;
    6329             :     Cost        total_cost;
    6330             :     Path       *epq_path;       /* Path to create plan to be executed when
    6331             :                                  * EvalPlanQual gets triggered. */
    6332             : 
    6333             :     /*
    6334             :      * Skip if this join combination has been considered already.
    6335             :      */
    6336        2394 :     if (joinrel->fdw_private)
    6337        1776 :         return;
    6338             : 
    6339             :     /*
    6340             :      * This code does not work for joins with lateral references, since those
    6341             :      * must have parameterized paths, which we don't generate yet.
    6342             :      */
    6343         744 :     if (!bms_is_empty(joinrel->lateral_relids))
    6344           8 :         return;
    6345             : 
    6346             :     /*
    6347             :      * Create unfinished PgFdwRelationInfo entry which is used to indicate
    6348             :      * that the join relation is already considered, so that we won't waste
    6349             :      * time in judging safety of join pushdown and adding the same paths again
    6350             :      * if found safe. Once we know that this join can be pushed down, we fill
    6351             :      * the entry.
    6352             :      */
    6353         736 :     fpinfo = (PgFdwRelationInfo *) palloc0(sizeof(PgFdwRelationInfo));
    6354         736 :     fpinfo->pushdown_safe = false;
    6355         736 :     joinrel->fdw_private = fpinfo;
    6356             :     /* attrs_used is only for base relations. */
    6357         736 :     fpinfo->attrs_used = NULL;
    6358             : 
    6359             :     /*
    6360             :      * If there is a possibility that EvalPlanQual will be executed, we need
    6361             :      * to be able to reconstruct the row using scans of the base relations.
    6362             :      * GetExistingLocalJoinPath will find a suitable path for this purpose in
    6363             :      * the path list of the joinrel, if one exists.  We must be careful to
    6364             :      * call it before adding any ForeignPath, since the ForeignPath might
    6365             :      * dominate the only suitable local path available.  We also do it before
    6366             :      * calling foreign_join_ok(), since that function updates fpinfo and marks
    6367             :      * it as pushable if the join is found to be pushable.
    6368             :      */
    6369         736 :     if (root->parse->commandType == CMD_DELETE ||
    6370         708 :         root->parse->commandType == CMD_UPDATE ||
    6371         672 :         root->rowMarks)
    6372             :     {
    6373         120 :         epq_path = GetExistingLocalJoinPath(joinrel);
    6374         120 :         if (!epq_path)
    6375             :         {
    6376           0 :             elog(DEBUG3, "could not push down foreign join because a local path suitable for EPQ checks was not found");
    6377           0 :             return;
    6378             :         }
    6379             :     }
    6380             :     else
    6381         616 :         epq_path = NULL;
    6382             : 
    6383         736 :     if (!foreign_join_ok(root, joinrel, jointype, outerrel, innerrel, extra))
    6384             :     {
    6385             :         /* Free path required for EPQ if we copied one; we don't need it now */
    6386         118 :         if (epq_path)
    6387           4 :             pfree(epq_path);
    6388         118 :         return;
    6389             :     }
    6390             : 
    6391             :     /*
    6392             :      * Compute the selectivity and cost of the local_conds, so we don't have
    6393             :      * to do it over again for each path. The best we can do for these
    6394             :      * conditions is to estimate selectivity on the basis of local statistics.
    6395             :      * The local conditions are applied after the join has been computed on
    6396             :      * the remote side like quals in WHERE clause, so pass jointype as
    6397             :      * JOIN_INNER.
    6398             :      */
    6399         618 :     fpinfo->local_conds_sel = clauselist_selectivity(root,
    6400             :                                                      fpinfo->local_conds,
    6401             :                                                      0,
    6402             :                                                      JOIN_INNER,
    6403             :                                                      NULL);
    6404         618 :     cost_qual_eval(&fpinfo->local_conds_cost, fpinfo->local_conds, root);
    6405             : 
    6406             :     /*
    6407             :      * If we are going to estimate costs locally, estimate the join clause
    6408             :      * selectivity here while we have special join info.
    6409             :      */
    6410         618 :     if (!fpinfo->use_remote_estimate)
    6411         176 :         fpinfo->joinclause_sel = clauselist_selectivity(root, fpinfo->joinclauses,
    6412             :                                                         0, fpinfo->jointype,
    6413             :                                                         extra->sjinfo);
    6414             : 
    6415             :     /* Estimate costs for bare join relation */
    6416         618 :     estimate_path_cost_size(root, joinrel, NIL, NIL, NULL,
    6417             :                             &rows, &width, &startup_cost, &total_cost);
    6418             :     /* Now update this information in the joinrel */
    6419         618 :     joinrel->rows = rows;
    6420         618 :     joinrel->reltarget->width = width;
    6421         618 :     fpinfo->rows = rows;
    6422         618 :     fpinfo->width = width;
    6423         618 :     fpinfo->startup_cost = startup_cost;
    6424         618 :     fpinfo->total_cost = total_cost;
    6425             : 
    6426             :     /*
    6427             :      * Create a new join path and add it to the joinrel which represents a
    6428             :      * join between foreign tables.
    6429             :      */
    6430         618 :     joinpath = create_foreign_join_path(root,
    6431             :                                         joinrel,
    6432             :                                         NULL,   /* default pathtarget */
    6433             :                                         rows,
    6434             :                                         startup_cost,
    6435             :                                         total_cost,
    6436             :                                         NIL,    /* no pathkeys */
    6437             :                                         joinrel->lateral_relids,
    6438             :                                         epq_path,
    6439             :                                         extra->restrictlist,
    6440             :                                         NIL);   /* no fdw_private */
    6441             : 
    6442             :     /* Add generated path into joinrel by add_path(). */
    6443         618 :     add_path(joinrel, (Path *) joinpath);
    6444             : 
    6445             :     /* Consider pathkeys for the join relation */
    6446         618 :     add_paths_with_pathkeys_for_rel(root, joinrel, epq_path,
    6447             :                                     extra->restrictlist);
    6448             : 
    6449             :     /* XXX Consider parameterized paths for the join relation */
    6450             : }
    6451             : 
    6452             : /*
    6453             :  * Assess whether the aggregation, grouping and having operations can be pushed
    6454             :  * down to the foreign server.  As a side effect, save information we obtain in
    6455             :  * this function to PgFdwRelationInfo of the input relation.
    6456             :  */
    6457             : static bool
    6458         312 : foreign_grouping_ok(PlannerInfo *root, RelOptInfo *grouped_rel,
    6459             :                     Node *havingQual)
    6460             : {
    6461         312 :     Query      *query = root->parse;
    6462         312 :     PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) grouped_rel->fdw_private;
    6463         312 :     PathTarget *grouping_target = grouped_rel->reltarget;
    6464             :     PgFdwRelationInfo *ofpinfo;
    6465             :     ListCell   *lc;
    6466             :     int         i;
    6467         312 :     List       *tlist = NIL;
    6468             : 
    6469             :     /* We currently don't support pushing Grouping Sets. */
    6470         312 :     if (query->groupingSets)
    6471          12 :         return false;
    6472             : 
    6473             :     /* Get the fpinfo of the underlying scan relation. */
    6474         300 :     ofpinfo = (PgFdwRelationInfo *) fpinfo->outerrel->fdw_private;
    6475             : 
    6476             :     /*
    6477             :      * If underlying scan relation has any local conditions, those conditions
    6478             :      * are required to be applied before performing aggregation.  Hence the
    6479             :      * aggregate cannot be pushed down.
    6480             :      */
    6481         300 :     if (ofpinfo->local_conds)
    6482          18 :         return false;
    6483             : 
    6484             :     /*
    6485             :      * Examine grouping expressions, as well as other expressions we'd need to
    6486             :      * compute, and check whether they are safe to push down to the foreign
    6487             :      * server.  All GROUP BY expressions will be part of the grouping target
    6488             :      * and thus there is no need to search for them separately.  Add grouping
    6489             :      * expressions into target list which will be passed to foreign server.
    6490             :      *
    6491             :      * A tricky fine point is that we must not put any expression into the
    6492             :      * target list that is just a foreign param (that is, something that
    6493             :      * deparse.c would conclude has to be sent to the foreign server).  If we
    6494             :      * do, the expression will also appear in the fdw_exprs list of the plan
    6495             :      * node, and setrefs.c will get confused and decide that the fdw_exprs
    6496             :      * entry is actually a reference to the fdw_scan_tlist entry, resulting in
    6497             :      * a broken plan.  Somewhat oddly, it's OK if the expression contains such
    6498             :      * a node, as long as it's not at top level; then no match is possible.
    6499             :      */
    6500         282 :     i = 0;
    6501         834 :     foreach(lc, grouping_target->exprs)
    6502             :     {
    6503         588 :         Expr       *expr = (Expr *) lfirst(lc);
    6504         588 :         Index       sgref = get_pathtarget_sortgroupref(grouping_target, i);
    6505             :         ListCell   *l;
    6506             : 
    6507             :         /*
    6508             :          * Check whether this expression is part of GROUP BY clause.  Note we
    6509             :          * check the whole GROUP BY clause not just processed_groupClause,
    6510             :          * because we will ship all of it, cf. appendGroupByClause.
    6511             :          */
    6512         588 :         if (sgref && get_sortgroupref_clause_noerr(sgref, query->groupClause))
    6513         184 :         {
    6514             :             TargetEntry *tle;
    6515             : 
    6516             :             /*
    6517             :              * If any GROUP BY expression is not shippable, then we cannot
    6518             :              * push down aggregation to the foreign server.
    6519             :              */
    6520         190 :             if (!is_foreign_expr(root, grouped_rel, expr))
    6521          36 :                 return false;
    6522             : 
    6523             :             /*
    6524             :              * If it would be a foreign param, we can't put it into the tlist,
    6525             :              * so we have to fail.
    6526             :              */
    6527         188 :             if (is_foreign_param(root, grouped_rel, expr))
    6528           4 :                 return false;
    6529             : 
    6530             :             /*
    6531             :              * Pushable, so add to tlist.  We need to create a TLE for this
    6532             :              * expression and apply the sortgroupref to it.  We cannot use
    6533             :              * add_to_flat_tlist() here because that avoids making duplicate
    6534             :              * entries in the tlist.  If there are duplicate entries with
    6535             :              * distinct sortgrouprefs, we have to duplicate that situation in
    6536             :              * the output tlist.
    6537             :              */
    6538         184 :             tle = makeTargetEntry(expr, list_length(tlist) + 1, NULL, false);
    6539         184 :             tle->ressortgroupref = sgref;
    6540         184 :             tlist = lappend(tlist, tle);
    6541             :         }
    6542             :         else
    6543             :         {
    6544             :             /*
    6545             :              * Non-grouping expression we need to compute.  Can we ship it
    6546             :              * as-is to the foreign server?
    6547             :              */
    6548         398 :             if (is_foreign_expr(root, grouped_rel, expr) &&
    6549         356 :                 !is_foreign_param(root, grouped_rel, expr))
    6550         352 :             {
    6551             :                 /* Yes, so add to tlist as-is; OK to suppress duplicates */
    6552         352 :                 tlist = add_to_flat_tlist(tlist, list_make1(expr));
    6553             :             }
    6554             :             else
    6555             :             {
    6556             :                 /* Not pushable as a whole; extract its Vars and aggregates */
    6557             :                 List       *aggvars;
    6558             : 
    6559          46 :                 aggvars = pull_var_clause((Node *) expr,
    6560             :                                           PVC_INCLUDE_AGGREGATES);
    6561             : 
    6562             :                 /*
    6563             :                  * If any aggregate expression is not shippable, then we
    6564             :                  * cannot push down aggregation to the foreign server.  (We
    6565             :                  * don't have to check is_foreign_param, since that certainly
    6566             :                  * won't return true for any such expression.)
    6567             :                  */
    6568          46 :                 if (!is_foreign_expr(root, grouped_rel, (Expr *) aggvars))
    6569          30 :                     return false;
    6570             : 
    6571             :                 /*
    6572             :                  * Add aggregates, if any, into the targetlist.  Plain Vars
    6573             :                  * outside an aggregate can be ignored, because they should be
    6574             :                  * either same as some GROUP BY column or part of some GROUP
    6575             :                  * BY expression.  In either case, they are already part of
    6576             :                  * the targetlist and thus no need to add them again.  In fact
    6577             :                  * including plain Vars in the tlist when they do not match a
    6578             :                  * GROUP BY column would cause the foreign server to complain
    6579             :                  * that the shipped query is invalid.
    6580             :                  */
    6581          28 :                 foreach(l, aggvars)
    6582             :                 {
    6583          12 :                     Expr       *aggref = (Expr *) lfirst(l);
    6584             : 
    6585          12 :                     if (IsA(aggref, Aggref))
    6586           8 :                         tlist = add_to_flat_tlist(tlist, list_make1(aggref));
    6587             :                 }
    6588             :             }
    6589             :         }
    6590             : 
    6591         552 :         i++;
    6592             :     }
    6593             : 
    6594             :     /*
    6595             :      * Classify the pushable and non-pushable HAVING clauses and save them in
    6596             :      * remote_conds and local_conds of the grouped rel's fpinfo.
    6597             :      */
    6598         246 :     if (havingQual)
    6599             :     {
    6600          68 :         foreach(lc, (List *) havingQual)
    6601             :         {
    6602          38 :             Expr       *expr = (Expr *) lfirst(lc);
    6603             :             RestrictInfo *rinfo;
    6604             : 
    6605             :             /*
    6606             :              * Currently, the core code doesn't wrap havingQuals in
    6607             :              * RestrictInfos, so we must make our own.
    6608             :              */
    6609             :             Assert(!IsA(expr, RestrictInfo));
    6610          38 :             rinfo = make_restrictinfo(root,
    6611             :                                       expr,
    6612             :                                       true,
    6613             :                                       false,
    6614             :                                       false,
    6615             :                                       false,
    6616             :                                       root->qual_security_level,
    6617             :                                       grouped_rel->relids,
    6618             :                                       NULL,
    6619             :                                       NULL);
    6620          38 :             if (is_foreign_expr(root, grouped_rel, expr))
    6621          32 :                 fpinfo->remote_conds = lappend(fpinfo->remote_conds, rinfo);
    6622             :             else
    6623           6 :                 fpinfo->local_conds = lappend(fpinfo->local_conds, rinfo);
    6624             :         }
    6625             :     }
    6626             : 
    6627             :     /*
    6628             :      * If there are any local conditions, pull Vars and aggregates from it and
    6629             :      * check whether they are safe to pushdown or not.
    6630             :      */
    6631         246 :     if (fpinfo->local_conds)
    6632             :     {
    6633           6 :         List       *aggvars = NIL;
    6634             : 
    6635          12 :         foreach(lc, fpinfo->local_conds)
    6636             :         {
    6637           6 :             RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
    6638             : 
    6639           6 :             aggvars = list_concat(aggvars,
    6640           6 :                                   pull_var_clause((Node *) rinfo->clause,
    6641             :                                                   PVC_INCLUDE_AGGREGATES));
    6642             :         }
    6643             : 
    6644          14 :         foreach(lc, aggvars)
    6645             :         {
    6646          10 :             Expr       *expr = (Expr *) lfirst(lc);
    6647             : 
    6648             :             /*
    6649             :              * If aggregates within local conditions are not safe to push
    6650             :              * down, then we cannot push down the query.  Vars are already
    6651             :              * part of GROUP BY clause which are checked above, so no need to
    6652             :              * access them again here.  Again, we need not check
    6653             :              * is_foreign_param for a foreign aggregate.
    6654             :              */
    6655          10 :             if (IsA(expr, Aggref))
    6656             :             {
    6657          10 :                 if (!is_foreign_expr(root, grouped_rel, expr))
    6658           2 :                     return false;
    6659             : 
    6660           8 :                 tlist = add_to_flat_tlist(tlist, list_make1(expr));
    6661             :             }
    6662             :         }
    6663             :     }
    6664             : 
    6665             :     /* Store generated targetlist */
    6666         244 :     fpinfo->grouped_tlist = tlist;
    6667             : 
    6668             :     /* Safe to pushdown */
    6669         244 :     fpinfo->pushdown_safe = true;
    6670             : 
    6671             :     /*
    6672             :      * Set # of retrieved rows and cached relation costs to some negative
    6673             :      * value, so that we can detect when they are set to some sensible values,
    6674             :      * during one (usually the first) of the calls to estimate_path_cost_size.
    6675             :      */
    6676         244 :     fpinfo->retrieved_rows = -1;
    6677         244 :     fpinfo->rel_startup_cost = -1;
    6678         244 :     fpinfo->rel_total_cost = -1;
    6679             : 
    6680             :     /*
    6681             :      * Set the string describing this grouped relation to be used in EXPLAIN
    6682             :      * output of corresponding ForeignScan.  Note that the decoration we add
    6683             :      * to the base relation name mustn't include any digits, or it'll confuse
    6684             :      * postgresExplainForeignScan.
    6685             :      */
    6686         244 :     fpinfo->relation_name = psprintf("Aggregate on (%s)",
    6687             :                                      ofpinfo->relation_name);
    6688             : 
    6689         244 :     return true;
    6690             : }
    6691             : 
    6692             : /*
    6693             :  * postgresGetForeignUpperPaths
    6694             :  *      Add paths for post-join operations like aggregation, grouping etc. if
    6695             :  *      corresponding operations are safe to push down.
    6696             :  */
    6697             : static void
    6698        1876 : postgresGetForeignUpperPaths(PlannerInfo *root, UpperRelationKind stage,
    6699             :                              RelOptInfo *input_rel, RelOptInfo *output_rel,
    6700             :                              void *extra)
    6701             : {
    6702             :     PgFdwRelationInfo *fpinfo;
    6703             : 
    6704             :     /*
    6705             :      * If input rel is not safe to pushdown, then simply return as we cannot
    6706             :      * perform any post-join operations on the foreign server.
    6707             :      */
    6708        1876 :     if (!input_rel->fdw_private ||
    6709        1744 :         !((PgFdwRelationInfo *) input_rel->fdw_private)->pushdown_safe)
    6710         244 :         return;
    6711             : 
    6712             :     /* Ignore stages we don't support; and skip any duplicate calls. */
    6713        1632 :     if ((stage != UPPERREL_GROUP_AGG &&
    6714        1028 :          stage != UPPERREL_ORDERED &&
    6715        1598 :          stage != UPPERREL_FINAL) ||
    6716        1598 :         output_rel->fdw_private)
    6717          34 :         return;
    6718             : 
    6719        1598 :     fpinfo = (PgFdwRelationInfo *) palloc0(sizeof(PgFdwRelationInfo));
    6720        1598 :     fpinfo->pushdown_safe = false;
    6721        1598 :     fpinfo->stage = stage;
    6722        1598 :     output_rel->fdw_private = fpinfo;
    6723             : 
    6724        1598 :     switch (stage)
    6725             :     {
    6726         312 :         case UPPERREL_GROUP_AGG:
    6727         312 :             add_foreign_grouping_paths(root, input_rel, output_rel,
    6728             :                                        (GroupPathExtraData *) extra);
    6729         310 :             break;
    6730         292 :         case UPPERREL_ORDERED:
    6731         292 :             add_foreign_ordered_paths(root, input_rel, output_rel);
    6732         292 :             break;
    6733         994 :         case UPPERREL_FINAL:
    6734         994 :             add_foreign_final_paths(root, input_rel, output_rel,
    6735             :                                     (FinalPathExtraData *) extra);
    6736         994 :             break;
    6737           0 :         default:
    6738           0 :             elog(ERROR, "unexpected upper relation: %d", (int) stage);
    6739             :             break;
    6740             :     }
    6741             : }
    6742             : 
    6743             : /*
    6744             :  * add_foreign_grouping_paths
    6745             :  *      Add foreign path for grouping and/or aggregation.
    6746             :  *
    6747             :  * Given input_rel represents the underlying scan.  The paths are added to the
    6748             :  * given grouped_rel.
    6749             :  */
    6750             : static void
    6751         312 : add_foreign_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel,
    6752             :                            RelOptInfo *grouped_rel,
    6753             :                            GroupPathExtraData *extra)
    6754             : {
    6755         312 :     Query      *parse = root->parse;
    6756         312 :     PgFdwRelationInfo *ifpinfo = input_rel->fdw_private;
    6757         312 :     PgFdwRelationInfo *fpinfo = grouped_rel->fdw_private;
    6758             :     ForeignPath *grouppath;
    6759             :     double      rows;
    6760             :     int         width;
    6761             :     Cost        startup_cost;
    6762             :     Cost        total_cost;
    6763             : 
    6764             :     /* Nothing to be done, if there is no grouping or aggregation required. */
    6765         312 :     if (!parse->groupClause && !parse->groupingSets && !parse->hasAggs &&
    6766           0 :         !root->hasHavingQual)
    6767          68 :         return;
    6768             : 
    6769             :     Assert(extra->patype == PARTITIONWISE_AGGREGATE_NONE ||
    6770             :            extra->patype == PARTITIONWISE_AGGREGATE_FULL);
    6771             : 
    6772             :     /* save the input_rel as outerrel in fpinfo */
    6773         312 :     fpinfo->outerrel = input_rel;
    6774             : 
    6775             :     /*
    6776             :      * Copy foreign table, foreign server, user mapping, FDW options etc.
    6777             :      * details from the input relation's fpinfo.
    6778             :      */
    6779         312 :     fpinfo->table = ifpinfo->table;
    6780         312 :     fpinfo->server = ifpinfo->server;
    6781         312 :     fpinfo->user = ifpinfo->user;
    6782         312 :     merge_fdw_options(fpinfo, ifpinfo, NULL);
    6783             : 
    6784             :     /*
    6785             :      * Assess if it is safe to push down aggregation and grouping.
    6786             :      *
    6787             :      * Use HAVING qual from extra. In case of child partition, it will have
    6788             :      * translated Vars.
    6789             :      */
    6790         312 :     if (!foreign_grouping_ok(root, grouped_rel, extra->havingQual))
    6791          68 :         return;
    6792             : 
    6793             :     /*
    6794             :      * Compute the selectivity and cost of the local_conds, so we don't have
    6795             :      * to do it over again for each path.  (Currently we create just a single
    6796             :      * path here, but in future it would be possible that we build more paths
    6797             :      * such as pre-sorted paths as in postgresGetForeignPaths and
    6798             :      * postgresGetForeignJoinPaths.)  The best we can do for these conditions
    6799             :      * is to estimate selectivity on the basis of local statistics.
    6800             :      */
    6801         244 :     fpinfo->local_conds_sel = clauselist_selectivity(root,
    6802             :                                                      fpinfo->local_conds,
    6803             :                                                      0,
    6804             :                                                      JOIN_INNER,
    6805             :                                                      NULL);
    6806             : 
    6807         244 :     cost_qual_eval(&fpinfo->local_conds_cost, fpinfo->local_conds, root);
    6808             : 
    6809             :     /* Estimate the cost of push down */
    6810         244 :     estimate_path_cost_size(root, grouped_rel, NIL, NIL, NULL,
    6811             :                             &rows, &width, &startup_cost, &total_cost);
    6812             : 
    6813             :     /* Now update this information in the fpinfo */
    6814         242 :     fpinfo->rows = rows;
    6815         242 :     fpinfo->width = width;
    6816         242 :     fpinfo->startup_cost = startup_cost;
    6817         242 :     fpinfo->total_cost = total_cost;
    6818             : 
    6819             :     /* Create and add foreign path to the grouping relation. */
    6820         242 :     grouppath = create_foreign_upper_path(root,
    6821             :                                           grouped_rel,
    6822         242 :                                           grouped_rel->reltarget,
    6823             :                                           rows,
    6824             :                                           startup_cost,
    6825             :                                           total_cost,
    6826             :                                           NIL,  /* no pathkeys */
    6827             :                                           NULL,
    6828             :                                           NIL,  /* no fdw_restrictinfo list */
    6829             :                                           NIL); /* no fdw_private */
    6830             : 
    6831             :     /* Add generated path into grouped_rel by add_path(). */
    6832         242 :     add_path(grouped_rel, (Path *) grouppath);
    6833             : }
    6834             : 
    6835             : /*
    6836             :  * add_foreign_ordered_paths
    6837             :  *      Add foreign paths for performing the final sort remotely.
    6838             :  *
    6839             :  * Given input_rel contains the source-data Paths.  The paths are added to the
    6840             :  * given ordered_rel.
    6841             :  */
    6842             : static void
    6843         292 : add_foreign_ordered_paths(PlannerInfo *root, RelOptInfo *input_rel,
    6844             :                           RelOptInfo *ordered_rel)
    6845             : {
    6846         292 :     Query      *parse = root->parse;
    6847         292 :     PgFdwRelationInfo *ifpinfo = input_rel->fdw_private;
    6848         292 :     PgFdwRelationInfo *fpinfo = ordered_rel->fdw_private;
    6849             :     PgFdwPathExtraData *fpextra;
    6850             :     double      rows;
    6851             :     int         width;
    6852             :     Cost        startup_cost;
    6853             :     Cost        total_cost;
    6854             :     List       *fdw_private;
    6855             :     ForeignPath *ordered_path;
    6856             :     ListCell   *lc;
    6857             : 
    6858             :     /* Shouldn't get here unless the query has ORDER BY */
    6859             :     Assert(parse->sortClause);
    6860             : 
    6861             :     /* We don't support cases where there are any SRFs in the targetlist */
    6862         292 :     if (parse->hasTargetSRFs)
    6863         208 :         return;
    6864             : 
    6865             :     /* Save the input_rel as outerrel in fpinfo */
    6866         292 :     fpinfo->outerrel = input_rel;
    6867             : 
    6868             :     /*
    6869             :      * Copy foreign table, foreign server, user mapping, FDW options etc.
    6870             :      * details from the input relation's fpinfo.
    6871             :      */
    6872         292 :     fpinfo->table = ifpinfo->table;
    6873         292 :     fpinfo->server = ifpinfo->server;
    6874         292 :     fpinfo->user = ifpinfo->user;
    6875         292 :     merge_fdw_options(fpinfo, ifpinfo, NULL);
    6876             : 
    6877             :     /*
    6878             :      * If the input_rel is a base or join relation, we would already have
    6879             :      * considered pushing down the final sort to the remote server when
    6880             :      * creating pre-sorted foreign paths for that relation, because the
    6881             :      * query_pathkeys is set to the root->sort_pathkeys in that case (see
    6882             :      * standard_qp_callback()).
    6883             :      */
    6884         292 :     if (input_rel->reloptkind == RELOPT_BASEREL ||
    6885         214 :         input_rel->reloptkind == RELOPT_JOINREL)
    6886             :     {
    6887             :         Assert(root->query_pathkeys == root->sort_pathkeys);
    6888             : 
    6889             :         /* Safe to push down if the query_pathkeys is safe to push down */
    6890         200 :         fpinfo->pushdown_safe = ifpinfo->qp_is_pushdown_safe;
    6891             : 
    6892         200 :         return;
    6893             :     }
    6894             : 
    6895             :     /* The input_rel should be a grouping relation */
    6896             :     Assert(input_rel->reloptkind == RELOPT_UPPER_REL &&
    6897             :            ifpinfo->stage == UPPERREL_GROUP_AGG);
    6898             : 
    6899             :     /*
    6900             :      * We try to create a path below by extending a simple foreign path for
    6901             :      * the underlying grouping relation to perform the final sort remotely,
    6902             :      * which is stored into the fdw_private list of the resulting path.
    6903             :      */
    6904             : 
    6905             :     /* Assess if it is safe to push down the final sort */
    6906         188 :     foreach(lc, root->sort_pathkeys)
    6907             :     {
    6908         104 :         PathKey    *pathkey = (PathKey *) lfirst(lc);
    6909         104 :         EquivalenceClass *pathkey_ec = pathkey->pk_eclass;
    6910             : 
    6911             :         /*
    6912             :          * is_foreign_expr would detect volatile expressions as well, but
    6913             :          * checking ec_has_volatile here saves some cycles.
    6914             :          */
    6915         104 :         if (pathkey_ec->ec_has_volatile)
    6916           8 :             return;
    6917             : 
    6918             :         /*
    6919             :          * Can't push down the sort if pathkey's opfamily is not shippable.
    6920             :          */
    6921          96 :         if (!is_shippable(pathkey->pk_opfamily, OperatorFamilyRelationId,
    6922             :                           fpinfo))
    6923           0 :             return;
    6924             : 
    6925             :         /*
    6926             :          * The EC must contain a shippable EM that is computed in input_rel's
    6927             :          * reltarget, else we can't push down the sort.
    6928             :          */
    6929          96 :         if (find_em_for_rel_target(root,
    6930             :                                    pathkey_ec,
    6931             :                                    input_rel) == NULL)
    6932           0 :             return;
    6933             :     }
    6934             : 
    6935             :     /* Safe to push down */
    6936          84 :     fpinfo->pushdown_safe = true;
    6937             : 
    6938             :     /* Construct PgFdwPathExtraData */
    6939          84 :     fpextra = (PgFdwPathExtraData *) palloc0(sizeof(PgFdwPathExtraData));
    6940          84 :     fpextra->target = root->upper_targets[UPPERREL_ORDERED];
    6941          84 :     fpextra->has_final_sort = true;
    6942             : 
    6943             :     /* Estimate the costs of performing the final sort remotely */
    6944          84 :     estimate_path_cost_size(root, input_rel, NIL, root->sort_pathkeys, fpextra,
    6945             :                             &rows, &width, &startup_cost, &total_cost);
    6946             : 
    6947             :     /*
    6948             :      * Build the fdw_private list that will be used by postgresGetForeignPlan.
    6949             :      * Items in the list must match order in enum FdwPathPrivateIndex.
    6950             :      */
    6951          84 :     fdw_private = list_make2(makeBoolean(true), makeBoolean(false));
    6952             : 
    6953             :     /* Create foreign ordering path */
    6954          84 :     ordered_path = create_foreign_upper_path(root,
    6955             :                                              input_rel,
    6956          84 :                                              root->upper_targets[UPPERREL_ORDERED],
    6957             :                                              rows,
    6958             :                                              startup_cost,
    6959             :                                              total_cost,
    6960             :                                              root->sort_pathkeys,
    6961             :                                              NULL,  /* no extra plan */
    6962             :                                              NIL,   /* no fdw_restrictinfo
    6963             :                                                      * list */
    6964             :                                              fdw_private);
    6965             : 
    6966             :     /* and add it to the ordered_rel */
    6967          84 :     add_path(ordered_rel, (Path *) ordered_path);
    6968             : }
    6969             : 
    6970             : /*
    6971             :  * add_foreign_final_paths
    6972             :  *      Add foreign paths for performing the final processing remotely.
    6973             :  *
    6974             :  * Given input_rel contains the source-data Paths.  The paths are added to the
    6975             :  * given final_rel.
    6976             :  */
    6977             : static void
    6978         994 : add_foreign_final_paths(PlannerInfo *root, RelOptInfo *input_rel,
    6979             :                         RelOptInfo *final_rel,
    6980             :                         FinalPathExtraData *extra)
    6981             : {
    6982         994 :     Query      *parse = root->parse;
    6983         994 :     PgFdwRelationInfo *ifpinfo = (PgFdwRelationInfo *) input_rel->fdw_private;
    6984         994 :     PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) final_rel->fdw_private;
    6985         994 :     bool        has_final_sort = false;
    6986         994 :     List       *pathkeys = NIL;
    6987             :     PgFdwPathExtraData *fpextra;
    6988         994 :     bool        save_use_remote_estimate = false;
    6989             :     double      rows;
    6990             :     int         width;
    6991             :     Cost        startup_cost;
    6992             :     Cost        total_cost;
    6993             :     List       *fdw_private;
    6994             :     ForeignPath *final_path;
    6995             : 
    6996             :     /*
    6997             :      * Currently, we only support this for SELECT commands
    6998             :      */
    6999         994 :     if (parse->commandType != CMD_SELECT)
    7000         758 :         return;
    7001             : 
    7002             :     /*
    7003             :      * No work if there is no FOR UPDATE/SHARE clause and if there is no need
    7004             :      * to add a LIMIT node
    7005             :      */
    7006         780 :     if (!parse->rowMarks && !extra->limit_needed)
    7007         520 :         return;
    7008             : 
    7009             :     /* We don't support cases where there are any SRFs in the targetlist */
    7010         260 :     if (parse->hasTargetSRFs)
    7011           0 :         return;
    7012             : 
    7013             :     /* Save the input_rel as outerrel in fpinfo */
    7014         260 :     fpinfo->outerrel = input_rel;
    7015             : 
    7016             :     /*
    7017             :      * Copy foreign table, foreign server, user mapping, FDW options etc.
    7018             :      * details from the input relation's fpinfo.
    7019             :      */
    7020         260 :     fpinfo->table = ifpinfo->table;
    7021         260 :     fpinfo->server = ifpinfo->server;
    7022         260 :     fpinfo->user = ifpinfo->user;
    7023         260 :     merge_fdw_options(fpinfo, ifpinfo, NULL);
    7024             : 
    7025             :     /*
    7026             :      * If there is no need to add a LIMIT node, there might be a ForeignPath
    7027             :      * in the input_rel's pathlist that implements all behavior of the query.
    7028             :      * Note: we would already have accounted for the query's FOR UPDATE/SHARE
    7029             :      * (if any) before we get here.
    7030             :      */
    7031         260 :     if (!extra->limit_needed)
    7032             :     {
    7033             :         ListCell   *lc;
    7034             : 
    7035             :         Assert(parse->rowMarks);
    7036             : 
    7037             :         /*
    7038             :          * Grouping and aggregation are not supported with FOR UPDATE/SHARE,
    7039             :          * so the input_rel should be a base, join, or ordered relation; and
    7040             :          * if it's an ordered relation, its input relation should be a base or
    7041             :          * join relation.
    7042             :          */
    7043             :         Assert(input_rel->reloptkind == RELOPT_BASEREL ||
    7044             :                input_rel->reloptkind == RELOPT_JOINREL ||
    7045             :                (input_rel->reloptkind == RELOPT_UPPER_REL &&
    7046             :                 ifpinfo->stage == UPPERREL_ORDERED &&
    7047             :                 (ifpinfo->outerrel->reloptkind == RELOPT_BASEREL ||
    7048             :                  ifpinfo->outerrel->reloptkind == RELOPT_JOINREL)));
    7049             : 
    7050           8 :         foreach(lc, input_rel->pathlist)
    7051             :         {
    7052           8 :             Path       *path = (Path *) lfirst(lc);
    7053             : 
    7054             :             /*
    7055             :              * apply_scanjoin_target_to_paths() uses create_projection_path()
    7056             :              * to adjust each of its input paths if needed, whereas
    7057             :              * create_ordered_paths() uses apply_projection_to_path() to do
    7058             :              * that.  So the former might have put a ProjectionPath on top of
    7059             :              * the ForeignPath; look through ProjectionPath and see if the
    7060             :              * path underneath it is ForeignPath.
    7061             :              */
    7062           8 :             if (IsA(path, ForeignPath) ||
    7063           0 :                 (IsA(path, ProjectionPath) &&
    7064           0 :                  IsA(((ProjectionPath *) path)->subpath, ForeignPath)))
    7065             :             {
    7066             :                 /*
    7067             :                  * Create foreign final path; this gets rid of a
    7068             :                  * no-longer-needed outer plan (if any), which makes the
    7069             :                  * EXPLAIN output look cleaner
    7070             :                  */
    7071           8 :                 final_path = create_foreign_upper_path(root,
    7072             :                                                        path->parent,
    7073             :                                                        path->pathtarget,
    7074             :                                                        path->rows,
    7075             :                                                        path->startup_cost,
    7076             :                                                        path->total_cost,
    7077             :                                                        path->pathkeys,
    7078             :                                                        NULL,    /* no extra plan */
    7079             :                                                        NIL, /* no fdw_restrictinfo
    7080             :                                                              * list */
    7081             :                                                        NIL);    /* no fdw_private */
    7082             : 
    7083             :                 /* and add it to the final_rel */
    7084           8 :                 add_path(final_rel, (Path *) final_path);
    7085             : 
    7086             :                 /* Safe to push down */
    7087           8 :                 fpinfo->pushdown_safe = true;
    7088             : 
    7089           8 :                 return;
    7090             :             }
    7091             :         }
    7092             : 
    7093             :         /*
    7094             :          * If we get here it means no ForeignPaths; since we would already
    7095             :          * have considered pushing down all operations for the query to the
    7096             :          * remote server, give up on it.
    7097             :          */
    7098           0 :         return;
    7099             :     }
    7100             : 
    7101             :     Assert(extra->limit_needed);
    7102             : 
    7103             :     /*
    7104             :      * If the input_rel is an ordered relation, replace the input_rel with its
    7105             :      * input relation
    7106             :      */
    7107         252 :     if (input_rel->reloptkind == RELOPT_UPPER_REL &&
    7108         140 :         ifpinfo->stage == UPPERREL_ORDERED)
    7109             :     {
    7110         140 :         input_rel = ifpinfo->outerrel;
    7111         140 :         ifpinfo = (PgFdwRelationInfo *) input_rel->fdw_private;
    7112         140 :         has_final_sort = true;
    7113         140 :         pathkeys = root->sort_pathkeys;
    7114             :     }
    7115             : 
    7116             :     /* The input_rel should be a base, join, or grouping relation */
    7117             :     Assert(input_rel->reloptkind == RELOPT_BASEREL ||
    7118             :            input_rel->reloptkind == RELOPT_JOINREL ||
    7119             :            (input_rel->reloptkind == RELOPT_UPPER_REL &&
    7120             :             ifpinfo->stage == UPPERREL_GROUP_AGG));
    7121             : 
    7122             :     /*
    7123             :      * We try to create a path below by extending a simple foreign path for
    7124             :      * the underlying base, join, or grouping relation to perform the final
    7125             :      * sort (if has_final_sort) and the LIMIT restriction remotely, which is
    7126             :      * stored into the fdw_private list of the resulting path.  (We
    7127             :      * re-estimate the costs of sorting the underlying relation, if
    7128             :      * has_final_sort.)
    7129             :      */
    7130             : 
    7131             :     /*
    7132             :      * Assess if it is safe to push down the LIMIT and OFFSET to the remote
    7133             :      * server
    7134             :      */
    7135             : 
    7136             :     /*
    7137             :      * If the underlying relation has any local conditions, the LIMIT/OFFSET
    7138             :      * cannot be pushed down.
    7139             :      */
    7140         252 :     if (ifpinfo->local_conds)
    7141          16 :         return;
    7142             : 
    7143             :     /*
    7144             :      * Also, the LIMIT/OFFSET cannot be pushed down, if their expressions are
    7145             :      * not safe to remote.
    7146             :      */
    7147         236 :     if (!is_foreign_expr(root, input_rel, (Expr *) parse->limitOffset) ||
    7148         236 :         !is_foreign_expr(root, input_rel, (Expr *) parse->limitCount))
    7149           0 :         return;
    7150             : 
    7151             :     /* Safe to push down */
    7152         236 :     fpinfo->pushdown_safe = true;
    7153             : 
    7154             :     /* Construct PgFdwPathExtraData */
    7155         236 :     fpextra = (PgFdwPathExtraData *) palloc0(sizeof(PgFdwPathExtraData));
    7156         236 :     fpextra->target = root->upper_targets[UPPERREL_FINAL];
    7157         236 :     fpextra->has_final_sort = has_final_sort;
    7158         236 :     fpextra->has_limit = extra->limit_needed;
    7159         236 :     fpextra->limit_tuples = extra->limit_tuples;
    7160         236 :     fpextra->count_est = extra->count_est;
    7161         236 :     fpextra->offset_est = extra->offset_est;
    7162             : 
    7163             :     /*
    7164             :      * Estimate the costs of performing the final sort and the LIMIT
    7165             :      * restriction remotely.  If has_final_sort is false, we wouldn't need to
    7166             :      * execute EXPLAIN anymore if use_remote_estimate, since the costs can be
    7167             :      * roughly estimated using the costs we already have for the underlying
    7168             :      * relation, in the same way as when use_remote_estimate is false.  Since
    7169             :      * it's pretty expensive to execute EXPLAIN, force use_remote_estimate to
    7170             :      * false in that case.
    7171             :      */
    7172         236 :     if (!fpextra->has_final_sort)
    7173             :     {
    7174         106 :         save_use_remote_estimate = ifpinfo->use_remote_estimate;
    7175         106 :         ifpinfo->use_remote_estimate = false;
    7176             :     }
    7177         236 :     estimate_path_cost_size(root, input_rel, NIL, pathkeys, fpextra,
    7178             :                             &rows, &width, &startup_cost, &total_cost);
    7179         236 :     if (!fpextra->has_final_sort)
    7180         106 :         ifpinfo->use_remote_estimate = save_use_remote_estimate;
    7181             : 
    7182             :     /*
    7183             :      * Build the fdw_private list that will be used by postgresGetForeignPlan.
    7184             :      * Items in the list must match order in enum FdwPathPrivateIndex.
    7185             :      */
    7186         236 :     fdw_private = list_make2(makeBoolean(has_final_sort),
    7187             :                              makeBoolean(extra->limit_needed));
    7188             : 
    7189             :     /*
    7190             :      * Create foreign final path; this gets rid of a no-longer-needed outer
    7191             :      * plan (if any), which makes the EXPLAIN output look cleaner
    7192             :      */
    7193         236 :     final_path = create_foreign_upper_path(root,
    7194             :                                            input_rel,
    7195         236 :                                            root->upper_targets[UPPERREL_FINAL],
    7196             :                                            rows,
    7197             :                                            startup_cost,
    7198             :                                            total_cost,
    7199             :                                            pathkeys,
    7200             :                                            NULL,    /* no extra plan */
    7201             :                                            NIL, /* no fdw_restrictinfo list */
    7202             :                                            fdw_private);
    7203             : 
    7204             :     /* and add it to the final_rel */
    7205         236 :     add_path(final_rel, (Path *) final_path);
    7206             : }
    7207             : 
    7208             : /*
    7209             :  * postgresIsForeignPathAsyncCapable
    7210             :  *      Check whether a given ForeignPath node is async-capable.
    7211             :  */
    7212             : static bool
    7213         466 : postgresIsForeignPathAsyncCapable(ForeignPath *path)
    7214             : {
    7215         466 :     RelOptInfo *rel = ((Path *) path)->parent;
    7216         466 :     PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) rel->fdw_private;
    7217             : 
    7218         466 :     return fpinfo->async_capable;
    7219             : }
    7220             : 
    7221             : /*
    7222             :  * postgresForeignAsyncRequest
    7223             :  *      Asynchronously request next tuple from a foreign PostgreSQL table.
    7224             :  */
    7225             : static void
    7226       12350 : postgresForeignAsyncRequest(AsyncRequest *areq)
    7227             : {
    7228       12350 :     produce_tuple_asynchronously(areq, true);
    7229       12350 : }
    7230             : 
    7231             : /*
    7232             :  * postgresForeignAsyncConfigureWait
    7233             :  *      Configure a file descriptor event for which we wish to wait.
    7234             :  */
    7235             : static void
    7236         572 : postgresForeignAsyncConfigureWait(AsyncRequest *areq)
    7237             : {
    7238         572 :     ForeignScanState *node = (ForeignScanState *) areq->requestee;
    7239         572 :     PgFdwScanState *fsstate = (PgFdwScanState *) node->fdw_state;
    7240         572 :     AsyncRequest *pendingAreq = fsstate->conn_state->pendingAreq;
    7241         572 :     AppendState *requestor = (AppendState *) areq->requestor;
    7242         572 :     WaitEventSet *set = requestor->as_eventset;
    7243             : 
    7244             :     /* This should not be called unless callback_pending */
    7245             :     Assert(areq->callback_pending);
    7246             : 
    7247             :     /*
    7248             :      * If process_pending_request() has been invoked on the given request
    7249             :      * before we get here, we might have some tuples already; in which case
    7250             :      * complete the request
    7251             :      */
    7252         572 :     if (fsstate->next_tuple < fsstate->num_tuples)
    7253             :     {
    7254          10 :         complete_pending_request(areq);
    7255          10 :         if (areq->request_complete)
    7256           6 :             return;
    7257             :         Assert(areq->callback_pending);
    7258             :     }
    7259             : 
    7260             :     /* We must have run out of tuples */
    7261             :     Assert(fsstate->next_tuple >= fsstate->num_tuples);
    7262             : 
    7263             :     /* The core code would have registered postmaster death event */
    7264             :     Assert(GetNumRegisteredWaitEvents(set) >= 1);
    7265             : 
    7266             :     /* Begin an asynchronous data fetch if not already done */
    7267         566 :     if (!pendingAreq)
    7268           8 :         fetch_more_data_begin(areq);
    7269         558 :     else if (pendingAreq->requestor != areq->requestor)
    7270             :     {
    7271             :         /*
    7272             :          * This is the case when the in-process request was made by another
    7273             :          * Append.  Note that it might be useless to process the request,
    7274             :          * because the query might not need tuples from that Append anymore.
    7275             :          * If there are any child subplans of the same parent that are ready
    7276             :          * for new requests, skip the given request.  Likewise, if there are
    7277             :          * any configured events other than the postmaster death event, skip
    7278             :          * it.  Otherwise, process the in-process request, then begin a fetch
    7279             :          * to configure the event below, because we might otherwise end up
    7280             :          * with no configured events other than the postmaster death event.
    7281             :          */
    7282          16 :         if (!bms_is_empty(requestor->as_needrequest))
    7283           0 :             return;
    7284          16 :         if (GetNumRegisteredWaitEvents(set) > 1)
    7285          12 :             return;
    7286           4 :         process_pending_request(pendingAreq);
    7287           4 :         fetch_more_data_begin(areq);
    7288             :     }
    7289         542 :     else if (pendingAreq->requestee != areq->requestee)
    7290             :     {
    7291             :         /*
    7292             :          * This is the case when the in-process request was made by the same
    7293             :          * parent but for a different child.  Since we configure only the
    7294             :          * event for the request made for that child, skip the given request.
    7295             :          */
    7296          24 :         return;
    7297             :     }
    7298             :     else
    7299             :         Assert(pendingAreq == areq);
    7300             : 
    7301         528 :     AddWaitEventToSet(set, WL_SOCKET_READABLE, PQsocket(fsstate->conn),
    7302             :                       NULL, areq);
    7303             : }
    7304             : 
    7305             : /*
    7306             :  * postgresForeignAsyncNotify
    7307             :  *      Fetch some more tuples from a file descriptor that becomes ready,
    7308             :  *      requesting next tuple.
    7309             :  */
    7310             : static void
    7311         296 : postgresForeignAsyncNotify(AsyncRequest *areq)
    7312             : {
    7313         296 :     ForeignScanState *node = (ForeignScanState *) areq->requestee;
    7314         296 :     PgFdwScanState *fsstate = (PgFdwScanState *) node->fdw_state;
    7315             : 
    7316             :     /* The core code would have initialized the callback_pending flag */
    7317             :     Assert(!areq->callback_pending);
    7318             : 
    7319             :     /*
    7320             :      * If process_pending_request() has been invoked on the given request
    7321             :      * before we get here, we might have some tuples already; in which case
    7322             :      * produce the next tuple
    7323             :      */
    7324         296 :     if (fsstate->next_tuple < fsstate->num_tuples)
    7325             :     {
    7326           0 :         produce_tuple_asynchronously(areq, true);
    7327           0 :         return;
    7328             :     }
    7329             : 
    7330             :     /* We must have run out of tuples */
    7331             :     Assert(fsstate->next_tuple >= fsstate->num_tuples);
    7332             : 
    7333             :     /* The request should be currently in-process */
    7334             :     Assert(fsstate->conn_state->pendingAreq == areq);
    7335             : 
    7336             :     /* On error, report the original query, not the FETCH. */
    7337         296 :     if (!PQconsumeInput(fsstate->conn))
    7338           0 :         pgfdw_report_error(ERROR, NULL, fsstate->conn, false, fsstate->query);
    7339             : 
    7340         296 :     fetch_more_data(node);
    7341             : 
    7342         296 :     produce_tuple_asynchronously(areq, true);
    7343             : }
    7344             : 
    7345             : /*
    7346             :  * Asynchronously produce next tuple from a foreign PostgreSQL table.
    7347             :  */
    7348             : static void
    7349       12656 : produce_tuple_asynchronously(AsyncRequest *areq, bool fetch)
    7350             : {
    7351       12656 :     ForeignScanState *node = (ForeignScanState *) areq->requestee;
    7352       12656 :     PgFdwScanState *fsstate = (PgFdwScanState *) node->fdw_state;
    7353       12656 :     AsyncRequest *pendingAreq = fsstate->conn_state->pendingAreq;
    7354             :     TupleTableSlot *result;
    7355             : 
    7356             :     /* This should not be called if the request is currently in-process */
    7357             :     Assert(areq != pendingAreq);
    7358             : 
    7359             :     /* Fetch some more tuples, if we've run out */
    7360       12656 :     if (fsstate->next_tuple >= fsstate->num_tuples)
    7361             :     {
    7362             :         /* No point in another fetch if we already detected EOF, though */
    7363         378 :         if (!fsstate->eof_reached)
    7364             :         {
    7365             :             /* Mark the request as pending for a callback */
    7366         258 :             ExecAsyncRequestPending(areq);
    7367             :             /* Begin another fetch if requested and if no pending request */
    7368         258 :             if (fetch && !pendingAreq)
    7369         248 :                 fetch_more_data_begin(areq);
    7370             :         }
    7371             :         else
    7372             :         {
    7373             :             /* There's nothing more to do; just return a NULL pointer */
    7374         120 :             result = NULL;
    7375             :             /* Mark the request as complete */
    7376         120 :             ExecAsyncRequestDone(areq, result);
    7377             :         }
    7378         378 :         return;
    7379             :     }
    7380             : 
    7381             :     /* Get a tuple from the ForeignScan node */
    7382       12278 :     result = areq->requestee->ExecProcNodeReal(areq->requestee);
    7383       12278 :     if (!TupIsNull(result))
    7384             :     {
    7385             :         /* Mark the request as complete */
    7386       12214 :         ExecAsyncRequestDone(areq, result);
    7387       12214 :         return;
    7388             :     }
    7389             : 
    7390             :     /* We must have run out of tuples */
    7391             :     Assert(fsstate->next_tuple >= fsstate->num_tuples);
    7392             : 
    7393             :     /* Fetch some more tuples, if we've not detected EOF yet */
    7394          64 :     if (!fsstate->eof_reached)
    7395             :     {
    7396             :         /* Mark the request as pending for a callback */
    7397          64 :         ExecAsyncRequestPending(areq);
    7398             :         /* Begin another fetch if requested and if no pending request */
    7399          64 :         if (fetch && !pendingAreq)
    7400          60 :             fetch_more_data_begin(areq);
    7401             :     }
    7402             :     else
    7403             :     {
    7404             :         /* There's nothing more to do; just return a NULL pointer */
    7405           0 :         result = NULL;
    7406             :         /* Mark the request as complete */
    7407           0 :         ExecAsyncRequestDone(areq, result);
    7408             :     }
    7409             : }
    7410             : 
    7411             : /*
    7412             :  * Begin an asynchronous data fetch.
    7413             :  *
    7414             :  * Note: this function assumes there is no currently-in-progress asynchronous
    7415             :  * data fetch.
    7416             :  *
    7417             :  * Note: fetch_more_data must be called to fetch the result.
    7418             :  */
    7419             : static void
    7420         320 : fetch_more_data_begin(AsyncRequest *areq)
    7421             : {
    7422         320 :     ForeignScanState *node = (ForeignScanState *) areq->requestee;
    7423         320 :     PgFdwScanState *fsstate = (PgFdwScanState *) node->fdw_state;
    7424             :     char        sql[64];
    7425             : 
    7426             :     Assert(!fsstate->conn_state->pendingAreq);
    7427             : 
    7428             :     /* Create the cursor synchronously. */
    7429         320 :     if (!fsstate->cursor_exists)
    7430         100 :         create_cursor(node);
    7431             : 
    7432             :     /* We will send this query, but not wait for the response. */
    7433         318 :     snprintf(sql, sizeof(sql), "FETCH %d FROM c%u",
    7434             :              fsstate->fetch_size, fsstate->cursor_number);
    7435             : 
    7436         318 :     if (!PQsendQuery(fsstate->conn, sql))
    7437           0 :         pgfdw_report_error(ERROR, NULL, fsstate->conn, false, fsstate->query);
    7438             : 
    7439             :     /* Remember that the request is in process */
    7440         318 :     fsstate->conn_state->pendingAreq = areq;
    7441         318 : }
    7442             : 
    7443             : /*
    7444             :  * Process a pending asynchronous request.
    7445             :  */
    7446             : void
    7447          18 : process_pending_request(AsyncRequest *areq)
    7448             : {
    7449          18 :     ForeignScanState *node = (ForeignScanState *) areq->requestee;
    7450          18 :     PgFdwScanState *fsstate = (PgFdwScanState *) node->fdw_state;
    7451             : 
    7452             :     /* The request would have been pending for a callback */
    7453             :     Assert(areq->callback_pending);
    7454             : 
    7455             :     /* The request should be currently in-process */
    7456             :     Assert(fsstate->conn_state->pendingAreq == areq);
    7457             : 
    7458          18 :     fetch_more_data(node);
    7459             : 
    7460             :     /*
    7461             :      * If we didn't get any tuples, must be end of data; complete the request
    7462             :      * now.  Otherwise, we postpone completing the request until we are called
    7463             :      * from postgresForeignAsyncConfigureWait()/postgresForeignAsyncNotify().
    7464             :      */
    7465          18 :     if (fsstate->next_tuple >= fsstate->num_tuples)
    7466             :     {
    7467             :         /* Unlike AsyncNotify, we unset callback_pending ourselves */
    7468           0 :         areq->callback_pending = false;
    7469             :         /* Mark the request as complete */
    7470           0 :         ExecAsyncRequestDone(areq, NULL);
    7471             :         /* Unlike AsyncNotify, we call ExecAsyncResponse ourselves */
    7472           0 :         ExecAsyncResponse(areq);
    7473             :     }
    7474          18 : }
    7475             : 
    7476             : /*
    7477             :  * Complete a pending asynchronous request.
    7478             :  */
    7479             : static void
    7480          10 : complete_pending_request(AsyncRequest *areq)
    7481             : {
    7482             :     /* The request would have been pending for a callback */
    7483             :     Assert(areq->callback_pending);
    7484             : 
    7485             :     /* Unlike AsyncNotify, we unset callback_pending ourselves */
    7486          10 :     areq->callback_pending = false;
    7487             : 
    7488             :     /* We begin a fetch afterwards if necessary; don't fetch */
    7489          10 :     produce_tuple_asynchronously(areq, false);
    7490             : 
    7491             :     /* Unlike AsyncNotify, we call ExecAsyncResponse ourselves */
    7492          10 :     ExecAsyncResponse(areq);
    7493             : 
    7494             :     /* Also, we do instrumentation ourselves, if required */
    7495          10 :     if (areq->requestee->instrument)
    7496           2 :         InstrUpdateTupleCount(areq->requestee->instrument,
    7497           2 :                               TupIsNull(areq->result) ? 0.0 : 1.0);
    7498          10 : }
    7499             : 
    7500             : /*
    7501             :  * Create a tuple from the specified row of the PGresult.
    7502             :  *
    7503             :  * rel is the local representation of the foreign table, attinmeta is
    7504             :  * conversion data for the rel's tupdesc, and retrieved_attrs is an
    7505             :  * integer list of the table column numbers present in the PGresult.
    7506             :  * fsstate is the ForeignScan plan node's execution state.
    7507             :  * temp_context is a working context that can be reset after each tuple.
    7508             :  *
    7509             :  * Note: either rel or fsstate, but not both, can be NULL.  rel is NULL
    7510             :  * if we're processing a remote join, while fsstate is NULL in a non-query
    7511             :  * context such as ANALYZE, or if we're processing a non-scan query node.
    7512             :  */
    7513             : static HeapTuple
    7514      170532 : make_tuple_from_result_row(PGresult *res,
    7515             :                            int row,
    7516             :                            Relation rel,
    7517             :                            AttInMetadata *attinmeta,
    7518             :                            List *retrieved_attrs,
    7519             :                            ForeignScanState *fsstate,
    7520             :                            MemoryContext temp_context)
    7521             : {
    7522             :     HeapTuple   tuple;
    7523             :     TupleDesc   tupdesc;
    7524             :     Datum      *values;
    7525             :     bool       *nulls;
    7526      170532 :     ItemPointer ctid = NULL;
    7527             :     ConversionLocation errpos;
    7528             :     ErrorContextCallback errcallback;
    7529             :     MemoryContext oldcontext;
    7530             :     ListCell   *lc;
    7531             :     int         j;
    7532             : 
    7533             :     Assert(row < PQntuples(res));
    7534             : 
    7535             :     /*
    7536             :      * Do the following work in a temp context that we reset after each tuple.
    7537             :      * This cleans up not only the data we have direct access to, but any
    7538             :      * cruft the I/O functions might leak.
    7539             :      */
    7540      170532 :     oldcontext = MemoryContextSwitchTo(temp_context);
    7541             : 
    7542             :     /*
    7543             :      * Get the tuple descriptor for the row.  Use the rel's tupdesc if rel is
    7544             :      * provided, otherwise look to the scan node's ScanTupleSlot.
    7545             :      */
    7546      170532 :     if (rel)
    7547       98726 :         tupdesc = RelationGetDescr(rel);
    7548             :     else
    7549             :     {
    7550             :         Assert(fsstate);
    7551       71806 :         tupdesc = fsstate->ss.ss_ScanTupleSlot->tts_tupleDescriptor;
    7552             :     }
    7553             : 
    7554      170532 :     values = (Datum *) palloc0(tupdesc->natts * sizeof(Datum));
    7555      170532 :     nulls = (bool *) palloc(tupdesc->natts * sizeof(bool));
    7556             :     /* Initialize to nulls for any columns not present in result */
    7557      170532 :     memset(nulls, true, tupdesc->natts * sizeof(bool));
    7558             : 
    7559             :     /*
    7560             :      * Set up and install callback to report where conversion error occurs.
    7561             :      */
    7562      170532 :     errpos.cur_attno = 0;
    7563      170532 :     errpos.rel = rel;
    7564      170532 :     errpos.fsstate = fsstate;
    7565      170532 :     errcallback.callback = conversion_error_callback;
    7566      170532 :     errcallback.arg = (void *) &errpos;
    7567      170532 :     errcallback.previous = error_context_stack;
    7568      170532 :     error_context_stack = &errcallback;
    7569             : 
    7570             :     /*
    7571             :      * i indexes columns in the relation, j indexes columns in the PGresult.
    7572             :      */
    7573      170532 :     j = 0;
    7574      636358 :     foreach(lc, retrieved_attrs)
    7575             :     {
    7576      465836 :         int         i = lfirst_int(lc);
    7577             :         char       *valstr;
    7578             : 
    7579             :         /* fetch next column's textual value */
    7580      465836 :         if (PQgetisnull(res, row, j))
    7581        1366 :             valstr = NULL;
    7582             :         else
    7583      464470 :             valstr = PQgetvalue(res, row, j);
    7584             : 
    7585             :         /*
    7586             :          * convert value to internal representation
    7587             :          *
    7588             :          * Note: we ignore system columns other than ctid and oid in result
    7589             :          */
    7590      465836 :         errpos.cur_attno = i;
    7591      465836 :         if (i > 0)
    7592             :         {
    7593             :             /* ordinary column */
    7594             :             Assert(i <= tupdesc->natts);
    7595      463634 :             nulls[i - 1] = (valstr == NULL);
    7596             :             /* Apply the input function even to nulls, to support domains */
    7597      463624 :             values[i - 1] = InputFunctionCall(&attinmeta->attinfuncs[i - 1],
    7598             :                                               valstr,
    7599      463634 :                                               attinmeta->attioparams[i - 1],
    7600      463634 :                                               attinmeta->atttypmods[i - 1]);
    7601             :         }
    7602        2202 :         else if (i == SelfItemPointerAttributeNumber)
    7603             :         {
    7604             :             /* ctid */
    7605        2202 :             if (valstr != NULL)
    7606             :             {
    7607             :                 Datum       datum;
    7608             : 
    7609        2202 :                 datum = DirectFunctionCall1(tidin, CStringGetDatum(valstr));
    7610        2202 :                 ctid = (ItemPointer) DatumGetPointer(datum);
    7611             :             }
    7612             :         }
    7613      465826 :         errpos.cur_attno = 0;
    7614             : 
    7615      465826 :         j++;
    7616             :     }
    7617             : 
    7618             :     /* Uninstall error context callback. */
    7619      170522 :     error_context_stack = errcallback.previous;
    7620             : 
    7621             :     /*
    7622             :      * Check we got the expected number of columns.  Note: j == 0 and
    7623             :      * PQnfields == 1 is expected, since deparse emits a NULL if no columns.
    7624             :      */
    7625      170522 :     if (j > 0 && j != PQnfields(res))
    7626           0 :         elog(ERROR, "remote query result does not match the foreign table");
    7627             : 
    7628             :     /*
    7629             :      * Build the result tuple in caller's memory context.
    7630             :      */
    7631      170522 :     MemoryContextSwitchTo(oldcontext);
    7632             : 
    7633      170522 :     tuple = heap_form_tuple(tupdesc, values, nulls);
    7634             : 
    7635             :     /*
    7636             :      * If we have a CTID to return, install it in both t_self and t_ctid.
    7637             :      * t_self is the normal place, but if the tuple is converted to a
    7638             :      * composite Datum, t_self will be lost; setting t_ctid allows CTID to be
    7639             :      * preserved during EvalPlanQual re-evaluations (see ROW_MARK_COPY code).
    7640             :      */
    7641      170522 :     if (ctid)
    7642        2202 :         tuple->t_self = tuple->t_data->t_ctid = *ctid;
    7643             : 
    7644             :     /*
    7645             :      * Stomp on the xmin, xmax, and cmin fields from the tuple created by
    7646             :      * heap_form_tuple.  heap_form_tuple actually creates the tuple with
    7647             :      * DatumTupleFields, not HeapTupleFields, but the executor expects
    7648             :      * HeapTupleFields and will happily extract system columns on that
    7649             :      * assumption.  If we don't do this then, for example, the tuple length
    7650             :      * ends up in the xmin field, which isn't what we want.
    7651             :      */
    7652      170522 :     HeapTupleHeaderSetXmax(tuple->t_data, InvalidTransactionId);
    7653      170522 :     HeapTupleHeaderSetXmin(tuple->t_data, InvalidTransactionId);
    7654      170522 :     HeapTupleHeaderSetCmin(tuple->t_data, InvalidTransactionId);
    7655             : 
    7656             :     /* Clean up */
    7657      170522 :     MemoryContextReset(temp_context);
    7658             : 
    7659      170522 :     return tuple;
    7660             : }
    7661             : 
    7662             : /*
    7663             :  * Callback function which is called when error occurs during column value
    7664             :  * conversion.  Print names of column and relation.
    7665             :  *
    7666             :  * Note that this function mustn't do any catalog lookups, since we are in
    7667             :  * an already-failed transaction.  Fortunately, we can get the needed info
    7668             :  * from the relation or the query's rangetable instead.
    7669             :  */
    7670             : static void
    7671          10 : conversion_error_callback(void *arg)
    7672             : {
    7673          10 :     ConversionLocation *errpos = (ConversionLocation *) arg;
    7674          10 :     Relation    rel = errpos->rel;
    7675          10 :     ForeignScanState *fsstate = errpos->fsstate;
    7676          10 :     const char *attname = NULL;
    7677          10 :     const char *relname = NULL;
    7678          10 :     bool        is_wholerow = false;
    7679             : 
    7680             :     /*
    7681             :      * If we're in a scan node, always use aliases from the rangetable, for
    7682             :      * consistency between the simple-relation and remote-join cases.  Look at
    7683             :      * the relation's tupdesc only if we're not in a scan node.
    7684             :      */
    7685          10 :     if (fsstate)
    7686             :     {
    7687             :         /* ForeignScan case */
    7688           8 :         ForeignScan *fsplan = castNode(ForeignScan, fsstate->ss.ps.plan);
    7689           8 :         int         varno = 0;
    7690           8 :         AttrNumber  colno = 0;
    7691             : 
    7692           8 :         if (fsplan->scan.scanrelid > 0)
    7693             :         {
    7694             :             /* error occurred in a scan against a foreign table */
    7695           2 :             varno = fsplan->scan.scanrelid;
    7696           2 :             colno = errpos->cur_attno;
    7697             :         }
    7698             :         else
    7699             :         {
    7700             :             /* error occurred in a scan against a foreign join */
    7701             :             TargetEntry *tle;
    7702             : 
    7703           6 :             tle = list_nth_node(TargetEntry, fsplan->fdw_scan_tlist,
    7704             :                                 errpos->cur_attno - 1);
    7705             : 
    7706             :             /*
    7707             :              * Target list can have Vars and expressions.  For Vars, we can
    7708             :              * get some information, however for expressions we can't.  Thus
    7709             :              * for expressions, just show generic context message.
    7710             :              */
    7711           6 :             if (IsA(tle->expr, Var))
    7712             :             {
    7713           4 :                 Var        *var = (Var *) tle->expr;
    7714             : 
    7715           4 :                 varno = var->varno;
    7716           4 :                 colno = var->varattno;
    7717             :             }
    7718             :         }
    7719             : 
    7720           8 :         if (varno > 0)
    7721             :         {
    7722           6 :             EState     *estate = fsstate->ss.ps.state;
    7723           6 :             RangeTblEntry *rte = exec_rt_fetch(varno, estate);
    7724             : 
    7725           6 :             relname = rte->eref->aliasname;
    7726             : 
    7727           6 :             if (colno == 0)
    7728           2 :                 is_wholerow = true;
    7729           4 :             else if (colno > 0 && colno <= list_length(rte->eref->colnames))
    7730           4 :                 attname = strVal(list_nth(rte->eref->colnames, colno - 1));
    7731           0 :             else if (colno == SelfItemPointerAttributeNumber)
    7732           0 :                 attname = "ctid";
    7733             :         }
    7734             :     }
    7735           2 :     else if (rel)
    7736             :     {
    7737             :         /* Non-ForeignScan case (we should always have a rel here) */
    7738           2 :         TupleDesc   tupdesc = RelationGetDescr(rel);
    7739             : 
    7740           2 :         relname = RelationGetRelationName(rel);
    7741           2 :         if (errpos->cur_attno > 0 && errpos->cur_attno <= tupdesc->natts)
    7742           2 :         {
    7743           2 :             Form_pg_attribute attr = TupleDescAttr(tupdesc,
    7744             :                                                    errpos->cur_attno - 1);
    7745             : 
    7746           2 :             attname = NameStr(attr->attname);
    7747             :         }
    7748           0 :         else if (errpos->cur_attno == SelfItemPointerAttributeNumber)
    7749           0 :             attname = "ctid";
    7750             :     }
    7751             : 
    7752          10 :     if (relname && is_wholerow)
    7753           2 :         errcontext("whole-row reference to foreign table \"%s\"", relname);
    7754           8 :     else if (relname && attname)
    7755           6 :         errcontext("column \"%s\" of foreign table \"%s\"", attname, relname);
    7756             :     else
    7757           2 :         errcontext("processing expression at position %d in select list",
    7758           2 :                    errpos->cur_attno);
    7759          10 : }
    7760             : 
    7761             : /*
    7762             :  * Given an EquivalenceClass and a foreign relation, find an EC member
    7763             :  * that can be used to sort the relation remotely according to a pathkey
    7764             :  * using this EC.
    7765             :  *
    7766             :  * If there is more than one suitable candidate, return an arbitrary
    7767             :  * one of them.  If there is none, return NULL.
    7768             :  *
    7769             :  * This checks that the EC member expression uses only Vars from the given
    7770             :  * rel and is shippable.  Caller must separately verify that the pathkey's
    7771             :  * ordering operator is shippable.
    7772             :  */
    7773             : EquivalenceMember *
    7774        3508 : find_em_for_rel(PlannerInfo *root, EquivalenceClass *ec, RelOptInfo *rel)
    7775             : {
    7776             :     ListCell   *lc;
    7777             : 
    7778        3508 :     PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) rel->fdw_private;
    7779             : 
    7780        6620 :     foreach(lc, ec->ec_members)
    7781             :     {
    7782        6072 :         EquivalenceMember *em = (EquivalenceMember *) lfirst(lc);
    7783             : 
    7784             :         /*
    7785             :          * Note we require !bms_is_empty, else we'd accept constant
    7786             :          * expressions which are not suitable for the purpose.
    7787             :          */
    7788        6072 :         if (bms_is_subset(em->em_relids, rel->relids) &&
    7789        6002 :             !bms_is_empty(em->em_relids) &&
    7790        5992 :             bms_is_empty(bms_intersect(em->em_relids, fpinfo->hidden_subquery_rels)) &&
    7791        2992 :             is_foreign_expr(root, rel, em->em_expr))
    7792        2960 :             return em;
    7793             :     }
    7794             : 
    7795         548 :     return NULL;
    7796             : }
    7797             : 
    7798             : /*
    7799             :  * Find an EquivalenceClass member that is to be computed as a sort column
    7800             :  * in the given rel's reltarget, and is shippable.
    7801             :  *
    7802             :  * If there is more than one suitable candidate, return an arbitrary
    7803             :  * one of them.  If there is none, return NULL.
    7804             :  *
    7805             :  * This checks that the EC member expression uses only Vars from the given
    7806             :  * rel and is shippable.  Caller must separately verify that the pathkey's
    7807             :  * ordering operator is shippable.
    7808             :  */
    7809             : EquivalenceMember *
    7810         502 : find_em_for_rel_target(PlannerInfo *root, EquivalenceClass *ec,
    7811             :                        RelOptInfo *rel)
    7812             : {
    7813         502 :     PathTarget *target = rel->reltarget;
    7814             :     ListCell   *lc1;
    7815             :     int         i;
    7816             : 
    7817         502 :     i = 0;
    7818         842 :     foreach(lc1, target->exprs)
    7819             :     {
    7820         842 :         Expr       *expr = (Expr *) lfirst(lc1);
    7821         842 :         Index       sgref = get_pathtarget_sortgroupref(target, i);
    7822             :         ListCell   *lc2;
    7823             : 
    7824             :         /* Ignore non-sort expressions */
    7825        1514 :         if (sgref == 0 ||
    7826         672 :             get_sortgroupref_clause_noerr(sgref,
    7827         672 :                                           root->parse->sortClause) == NULL)
    7828             :         {
    7829         186 :             i++;
    7830         186 :             continue;
    7831             :         }
    7832             : 
    7833             :         /* We ignore binary-compatible relabeling on both ends */
    7834         656 :         while (expr && IsA(expr, RelabelType))
    7835           0 :             expr = ((RelabelType *) expr)->arg;
    7836             : 
    7837             :         /* Locate an EquivalenceClass member matching this expr, if any */
    7838         818 :         foreach(lc2, ec->ec_members)
    7839             :         {
    7840         664 :             EquivalenceMember *em = (EquivalenceMember *) lfirst(lc2);
    7841             :             Expr       *em_expr;
    7842             : 
    7843             :             /* Don't match constants */
    7844         664 :             if (em->em_is_const)
    7845           0 :                 continue;
    7846             : 
    7847             :             /* Ignore child members */
    7848         664 :             if (em->em_is_child)
    7849           0 :                 continue;
    7850             : 
    7851             :             /* Match if same expression (after stripping relabel) */
    7852         664 :             em_expr = em->em_expr;
    7853         688 :             while (em_expr && IsA(em_expr, RelabelType))
    7854          24 :                 em_expr = ((RelabelType *) em_expr)->arg;
    7855             : 
    7856         664 :             if (!equal(em_expr, expr))
    7857         162 :                 continue;
    7858             : 
    7859             :             /* Check that expression (including relabels!) is shippable */
    7860         502 :             if (is_foreign_expr(root, rel, em->em_expr))
    7861         502 :                 return em;
    7862             :         }
    7863             : 
    7864         154 :         i++;
    7865             :     }
    7866             : 
    7867           0 :     return NULL;
    7868             : }
    7869             : 
    7870             : /*
    7871             :  * Determine batch size for a given foreign table. The option specified for
    7872             :  * a table has precedence.
    7873             :  */
    7874             : static int
    7875         282 : get_batch_size_option(Relation rel)
    7876             : {
    7877         282 :     Oid         foreigntableid = RelationGetRelid(rel);
    7878             :     ForeignTable *table;
    7879             :     ForeignServer *server;
    7880             :     List       *options;
    7881             :     ListCell   *lc;
    7882             : 
    7883             :     /* we use 1 by default, which means "no batching" */
    7884         282 :     int         batch_size = 1;
    7885             : 
    7886             :     /*
    7887             :      * Load options for table and server. We append server options after table
    7888             :      * options, because table options take precedence.
    7889             :      */
    7890         282 :     table = GetForeignTable(foreigntableid);
    7891         282 :     server = GetForeignServer(table->serverid);
    7892             : 
    7893         282 :     options = NIL;
    7894         282 :     options = list_concat(options, table->options);
    7895         282 :     options = list_concat(options, server->options);
    7896             : 
    7897             :     /* See if either table or server specifies batch_size. */
    7898        1482 :     foreach(lc, options)
    7899             :     {
    7900        1266 :         DefElem    *def = (DefElem *) lfirst(lc);
    7901             : 
    7902        1266 :         if (strcmp(def->defname, "batch_size") == 0)
    7903             :         {
    7904          66 :             (void) parse_int(defGetString(def), &batch_size, 0, NULL);
    7905          66 :             break;
    7906             :         }
    7907             :     }
    7908             : 
    7909         282 :     return batch_size;
    7910             : }

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