LCOV - code coverage report
Current view: top level - contrib/file_fdw - file_fdw.c (source / functions) Coverage Total Hit
Test: PostgreSQL 19devel Lines: 89.9 % 346 311
Test Date: 2026-03-11 06:14:41 Functions: 100.0 % 22 22
Legend: Lines:     hit not hit

            Line data    Source code
       1              : /*-------------------------------------------------------------------------
       2              :  *
       3              :  * file_fdw.c
       4              :  *        foreign-data wrapper for server-side flat files (or programs).
       5              :  *
       6              :  * Copyright (c) 2010-2026, PostgreSQL Global Development Group
       7              :  *
       8              :  * IDENTIFICATION
       9              :  *        contrib/file_fdw/file_fdw.c
      10              :  *
      11              :  *-------------------------------------------------------------------------
      12              :  */
      13              : #include "postgres.h"
      14              : 
      15              : #include <sys/stat.h>
      16              : #include <unistd.h>
      17              : 
      18              : #include "access/htup_details.h"
      19              : #include "access/reloptions.h"
      20              : #include "access/sysattr.h"
      21              : #include "access/table.h"
      22              : #include "catalog/pg_authid.h"
      23              : #include "catalog/pg_foreign_table.h"
      24              : #include "commands/copy.h"
      25              : #include "commands/copyfrom_internal.h"
      26              : #include "commands/defrem.h"
      27              : #include "commands/explain_format.h"
      28              : #include "commands/explain_state.h"
      29              : #include "commands/vacuum.h"
      30              : #include "executor/executor.h"
      31              : #include "foreign/fdwapi.h"
      32              : #include "foreign/foreign.h"
      33              : #include "miscadmin.h"
      34              : #include "nodes/makefuncs.h"
      35              : #include "optimizer/optimizer.h"
      36              : #include "optimizer/pathnode.h"
      37              : #include "optimizer/planmain.h"
      38              : #include "optimizer/restrictinfo.h"
      39              : #include "utils/acl.h"
      40              : #include "utils/memutils.h"
      41              : #include "utils/rel.h"
      42              : #include "utils/sampling.h"
      43              : #include "utils/varlena.h"
      44              : 
      45            1 : PG_MODULE_MAGIC_EXT(
      46              :                     .name = "file_fdw",
      47              :                     .version = PG_VERSION
      48              : );
      49              : 
      50              : /*
      51              :  * Describes the valid options for objects that use this wrapper.
      52              :  */
      53              : struct FileFdwOption
      54              : {
      55              :     const char *optname;
      56              :     Oid         optcontext;     /* Oid of catalog in which option may appear */
      57              : };
      58              : 
      59              : /*
      60              :  * Valid options for file_fdw.
      61              :  * These options are based on the options for the COPY FROM command.
      62              :  * But note that force_not_null and force_null are handled as boolean options
      63              :  * attached to a column, not as table options.
      64              :  *
      65              :  * Note: If you are adding new option for user mapping, you need to modify
      66              :  * fileGetOptions(), which currently doesn't bother to look at user mappings.
      67              :  */
      68              : static const struct FileFdwOption valid_options[] = {
      69              :     /* Data source options */
      70              :     {"filename", ForeignTableRelationId},
      71              :     {"program", ForeignTableRelationId},
      72              : 
      73              :     /* Format options */
      74              :     /* oids option is not supported */
      75              :     {"format", ForeignTableRelationId},
      76              :     {"header", ForeignTableRelationId},
      77              :     {"delimiter", ForeignTableRelationId},
      78              :     {"quote", ForeignTableRelationId},
      79              :     {"escape", ForeignTableRelationId},
      80              :     {"null", ForeignTableRelationId},
      81              :     {"default", ForeignTableRelationId},
      82              :     {"encoding", ForeignTableRelationId},
      83              :     {"on_error", ForeignTableRelationId},
      84              :     {"log_verbosity", ForeignTableRelationId},
      85              :     {"reject_limit", ForeignTableRelationId},
      86              :     {"force_not_null", AttributeRelationId},
      87              :     {"force_null", AttributeRelationId},
      88              : 
      89              :     /*
      90              :      * force_quote is not supported by file_fdw because it's for COPY TO.
      91              :      */
      92              : 
      93              :     /* Sentinel */
      94              :     {NULL, InvalidOid}
      95              : };
      96              : 
      97              : /*
      98              :  * FDW-specific information for RelOptInfo.fdw_private.
      99              :  */
     100              : typedef struct FileFdwPlanState
     101              : {
     102              :     char       *filename;       /* file or program to read from */
     103              :     bool        is_program;     /* true if filename represents an OS command */
     104              :     List       *options;        /* merged COPY options, excluding filename and
     105              :                                  * is_program */
     106              :     BlockNumber pages;          /* estimate of file's physical size */
     107              :     double      ntuples;        /* estimate of number of data rows */
     108              : } FileFdwPlanState;
     109              : 
     110              : /*
     111              :  * FDW-specific information for ForeignScanState.fdw_state.
     112              :  */
     113              : typedef struct FileFdwExecutionState
     114              : {
     115              :     char       *filename;       /* file or program to read from */
     116              :     bool        is_program;     /* true if filename represents an OS command */
     117              :     List       *options;        /* merged COPY options, excluding filename and
     118              :                                  * is_program */
     119              :     CopyFromState cstate;       /* COPY execution state */
     120              : } FileFdwExecutionState;
     121              : 
     122              : /*
     123              :  * SQL functions
     124              :  */
     125            2 : PG_FUNCTION_INFO_V1(file_fdw_handler);
     126            2 : PG_FUNCTION_INFO_V1(file_fdw_validator);
     127              : 
     128              : /*
     129              :  * FDW callback routines
     130              :  */
     131              : static void fileGetForeignRelSize(PlannerInfo *root,
     132              :                                   RelOptInfo *baserel,
     133              :                                   Oid foreigntableid);
     134              : static void fileGetForeignPaths(PlannerInfo *root,
     135              :                                 RelOptInfo *baserel,
     136              :                                 Oid foreigntableid);
     137              : static ForeignScan *fileGetForeignPlan(PlannerInfo *root,
     138              :                                        RelOptInfo *baserel,
     139              :                                        Oid foreigntableid,
     140              :                                        ForeignPath *best_path,
     141              :                                        List *tlist,
     142              :                                        List *scan_clauses,
     143              :                                        Plan *outer_plan);
     144              : static void fileExplainForeignScan(ForeignScanState *node, ExplainState *es);
     145              : static void fileBeginForeignScan(ForeignScanState *node, int eflags);
     146              : static TupleTableSlot *fileIterateForeignScan(ForeignScanState *node);
     147              : static void fileReScanForeignScan(ForeignScanState *node);
     148              : static void fileEndForeignScan(ForeignScanState *node);
     149              : static bool fileAnalyzeForeignTable(Relation relation,
     150              :                                     AcquireSampleRowsFunc *func,
     151              :                                     BlockNumber *totalpages);
     152              : static bool fileIsForeignScanParallelSafe(PlannerInfo *root, RelOptInfo *rel,
     153              :                                           RangeTblEntry *rte);
     154              : 
     155              : /*
     156              :  * Helper functions
     157              :  */
     158              : static bool is_valid_option(const char *option, Oid context);
     159              : static void fileGetOptions(Oid foreigntableid,
     160              :                            char **filename,
     161              :                            bool *is_program,
     162              :                            List **other_options);
     163              : static List *get_file_fdw_attribute_options(Oid relid);
     164              : static bool check_selective_binary_conversion(RelOptInfo *baserel,
     165              :                                               Oid foreigntableid,
     166              :                                               List **columns);
     167              : static void estimate_size(PlannerInfo *root, RelOptInfo *baserel,
     168              :                           FileFdwPlanState *fdw_private);
     169              : static void estimate_costs(PlannerInfo *root, RelOptInfo *baserel,
     170              :                            FileFdwPlanState *fdw_private,
     171              :                            Cost *startup_cost, Cost *total_cost);
     172              : static int  file_acquire_sample_rows(Relation onerel, int elevel,
     173              :                                      HeapTuple *rows, int targrows,
     174              :                                      double *totalrows, double *totaldeadrows);
     175              : 
     176              : 
     177              : /*
     178              :  * Foreign-data wrapper handler function: return a struct with pointers
     179              :  * to my callback routines.
     180              :  */
     181              : Datum
     182           21 : file_fdw_handler(PG_FUNCTION_ARGS)
     183              : {
     184           21 :     FdwRoutine *fdwroutine = makeNode(FdwRoutine);
     185              : 
     186           21 :     fdwroutine->GetForeignRelSize = fileGetForeignRelSize;
     187           21 :     fdwroutine->GetForeignPaths = fileGetForeignPaths;
     188           21 :     fdwroutine->GetForeignPlan = fileGetForeignPlan;
     189           21 :     fdwroutine->ExplainForeignScan = fileExplainForeignScan;
     190           21 :     fdwroutine->BeginForeignScan = fileBeginForeignScan;
     191           21 :     fdwroutine->IterateForeignScan = fileIterateForeignScan;
     192           21 :     fdwroutine->ReScanForeignScan = fileReScanForeignScan;
     193           21 :     fdwroutine->EndForeignScan = fileEndForeignScan;
     194           21 :     fdwroutine->AnalyzeForeignTable = fileAnalyzeForeignTable;
     195           21 :     fdwroutine->IsForeignScanParallelSafe = fileIsForeignScanParallelSafe;
     196              : 
     197           21 :     PG_RETURN_POINTER(fdwroutine);
     198              : }
     199              : 
     200              : /*
     201              :  * Validate the generic options given to a FOREIGN DATA WRAPPER, SERVER,
     202              :  * USER MAPPING or FOREIGN TABLE that uses file_fdw.
     203              :  *
     204              :  * Raise an ERROR if the option or its value is considered invalid.
     205              :  */
     206              : Datum
     207           67 : file_fdw_validator(PG_FUNCTION_ARGS)
     208              : {
     209           67 :     List       *options_list = untransformRelOptions(PG_GETARG_DATUM(0));
     210           67 :     Oid         catalog = PG_GETARG_OID(1);
     211           67 :     char       *filename = NULL;
     212           67 :     DefElem    *force_not_null = NULL;
     213           67 :     DefElem    *force_null = NULL;
     214           67 :     List       *other_options = NIL;
     215              :     ListCell   *cell;
     216              : 
     217              :     /*
     218              :      * Check that only options supported by file_fdw, and allowed for the
     219              :      * current object type, are given.
     220              :      */
     221          216 :     foreach(cell, options_list)
     222              :     {
     223          159 :         DefElem    *def = (DefElem *) lfirst(cell);
     224              : 
     225          159 :         if (!is_valid_option(def->defname, catalog))
     226              :         {
     227              :             const struct FileFdwOption *opt;
     228              :             const char *closest_match;
     229              :             ClosestMatchState match_state;
     230            9 :             bool        has_valid_options = false;
     231              : 
     232              :             /*
     233              :              * Unknown option specified, complain about it. Provide a hint
     234              :              * with a valid option that looks similar, if there is one.
     235              :              */
     236            9 :             initClosestMatch(&match_state, def->defname, 4);
     237          144 :             for (opt = valid_options; opt->optname; opt++)
     238              :             {
     239          135 :                 if (catalog == opt->optcontext)
     240              :                 {
     241           39 :                     has_valid_options = true;
     242           39 :                     updateClosestMatch(&match_state, opt->optname);
     243              :                 }
     244              :             }
     245              : 
     246            9 :             closest_match = getClosestMatch(&match_state);
     247            9 :             ereport(ERROR,
     248              :                     (errcode(ERRCODE_FDW_INVALID_OPTION_NAME),
     249              :                      errmsg("invalid option \"%s\"", def->defname),
     250              :                      has_valid_options ? closest_match ?
     251              :                      errhint("Perhaps you meant the option \"%s\".",
     252              :                              closest_match) : 0 :
     253              :                      errhint("There are no valid options in this context.")));
     254              :         }
     255              : 
     256              :         /*
     257              :          * Separate out filename, program, and column-specific options, since
     258              :          * ProcessCopyOptions won't accept them.
     259              :          */
     260          150 :         if (strcmp(def->defname, "filename") == 0 ||
     261          132 :             strcmp(def->defname, "program") == 0)
     262              :         {
     263           18 :             if (filename)
     264            0 :                 ereport(ERROR,
     265              :                         (errcode(ERRCODE_SYNTAX_ERROR),
     266              :                          errmsg("conflicting or redundant options")));
     267              : 
     268              :             /*
     269              :              * Check permissions for changing which file or program is used by
     270              :              * the file_fdw.
     271              :              *
     272              :              * Only members of the role 'pg_read_server_files' are allowed to
     273              :              * set the 'filename' option of a file_fdw foreign table, while
     274              :              * only members of the role 'pg_execute_server_program' are
     275              :              * allowed to set the 'program' option.  This is because we don't
     276              :              * want regular users to be able to control which file gets read
     277              :              * or which program gets executed.
     278              :              *
     279              :              * Putting this sort of permissions check in a validator is a bit
     280              :              * of a crock, but there doesn't seem to be any other place that
     281              :              * can enforce the check more cleanly.
     282              :              *
     283              :              * Note that the valid_options[] array disallows setting filename
     284              :              * and program at any options level other than foreign table ---
     285              :              * otherwise there'd still be a security hole.
     286              :              */
     287           18 :             if (strcmp(def->defname, "filename") == 0 &&
     288           18 :                 !has_privs_of_role(GetUserId(), ROLE_PG_READ_SERVER_FILES))
     289            1 :                 ereport(ERROR,
     290              :                         (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
     291              :                          errmsg("permission denied to set the \"%s\" option of a file_fdw foreign table",
     292              :                                 "filename"),
     293              :                          errdetail("Only roles with privileges of the \"%s\" role may set this option.",
     294              :                                    "pg_read_server_files")));
     295              : 
     296           17 :             if (strcmp(def->defname, "program") == 0 &&
     297            0 :                 !has_privs_of_role(GetUserId(), ROLE_PG_EXECUTE_SERVER_PROGRAM))
     298            0 :                 ereport(ERROR,
     299              :                         (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
     300              :                          errmsg("permission denied to set the \"%s\" option of a file_fdw foreign table",
     301              :                                 "program"),
     302              :                          errdetail("Only roles with privileges of the \"%s\" role may set this option.",
     303              :                                    "pg_execute_server_program")));
     304              : 
     305           17 :             filename = defGetString(def);
     306              :         }
     307              : 
     308              :         /*
     309              :          * force_not_null is a boolean option; after validation we can discard
     310              :          * it - it will be retrieved later in get_file_fdw_attribute_options()
     311              :          */
     312          132 :         else if (strcmp(def->defname, "force_not_null") == 0)
     313              :         {
     314            4 :             if (force_not_null)
     315            0 :                 ereport(ERROR,
     316              :                         (errcode(ERRCODE_SYNTAX_ERROR),
     317              :                          errmsg("conflicting or redundant options"),
     318              :                          errhint("Option \"force_not_null\" supplied more than once for a column.")));
     319            4 :             force_not_null = def;
     320              :             /* Don't care what the value is, as long as it's a legal boolean */
     321            4 :             (void) defGetBoolean(def);
     322              :         }
     323              :         /* See comments for force_not_null above */
     324          128 :         else if (strcmp(def->defname, "force_null") == 0)
     325              :         {
     326            4 :             if (force_null)
     327            0 :                 ereport(ERROR,
     328              :                         (errcode(ERRCODE_SYNTAX_ERROR),
     329              :                          errmsg("conflicting or redundant options"),
     330              :                          errhint("Option \"force_null\" supplied more than once for a column.")));
     331            4 :             force_null = def;
     332            4 :             (void) defGetBoolean(def);
     333              :         }
     334              :         else
     335          124 :             other_options = lappend(other_options, def);
     336              :     }
     337              : 
     338              :     /*
     339              :      * Now apply the core COPY code's validation logic for more checks.
     340              :      */
     341           57 :     ProcessCopyOptions(NULL, NULL, true, other_options);
     342              : 
     343              :     /*
     344              :      * Either filename or program option is required for file_fdw foreign
     345              :      * tables.
     346              :      */
     347           29 :     if (catalog == ForeignTableRelationId && filename == NULL)
     348            1 :         ereport(ERROR,
     349              :                 (errcode(ERRCODE_FDW_DYNAMIC_PARAMETER_VALUE_NEEDED),
     350              :                  errmsg("either filename or program is required for file_fdw foreign tables")));
     351              : 
     352           28 :     PG_RETURN_VOID();
     353              : }
     354              : 
     355              : /*
     356              :  * Check if the provided option is one of the valid options.
     357              :  * context is the Oid of the catalog holding the object the option is for.
     358              :  */
     359              : static bool
     360          159 : is_valid_option(const char *option, Oid context)
     361              : {
     362              :     const struct FileFdwOption *opt;
     363              : 
     364          982 :     for (opt = valid_options; opt->optname; opt++)
     365              :     {
     366          973 :         if (context == opt->optcontext && strcmp(opt->optname, option) == 0)
     367          150 :             return true;
     368              :     }
     369            9 :     return false;
     370              : }
     371              : 
     372              : /*
     373              :  * Fetch the options for a file_fdw foreign table.
     374              :  *
     375              :  * We have to separate out filename/program from the other options because
     376              :  * those must not appear in the options list passed to the core COPY code.
     377              :  */
     378              : static void
     379           81 : fileGetOptions(Oid foreigntableid,
     380              :                char **filename, bool *is_program, List **other_options)
     381              : {
     382              :     ForeignTable *table;
     383              :     ForeignServer *server;
     384              :     ForeignDataWrapper *wrapper;
     385              :     List       *options;
     386              :     ListCell   *lc;
     387              : 
     388              :     /*
     389              :      * Extract options from FDW objects.  We ignore user mappings because
     390              :      * file_fdw doesn't have any options that can be specified there.
     391              :      *
     392              :      * (XXX Actually, given the current contents of valid_options[], there's
     393              :      * no point in examining anything except the foreign table's own options.
     394              :      * Simplify?)
     395              :      */
     396           81 :     table = GetForeignTable(foreigntableid);
     397           81 :     server = GetForeignServer(table->serverid);
     398           81 :     wrapper = GetForeignDataWrapper(server->fdwid);
     399              : 
     400           81 :     options = NIL;
     401           81 :     options = list_concat(options, wrapper->options);
     402           81 :     options = list_concat(options, server->options);
     403           81 :     options = list_concat(options, table->options);
     404           81 :     options = list_concat(options, get_file_fdw_attribute_options(foreigntableid));
     405              : 
     406              :     /*
     407              :      * Separate out the filename or program option (we assume there is only
     408              :      * one).
     409              :      */
     410           81 :     *filename = NULL;
     411           81 :     *is_program = false;
     412          162 :     foreach(lc, options)
     413              :     {
     414          162 :         DefElem    *def = (DefElem *) lfirst(lc);
     415              : 
     416          162 :         if (strcmp(def->defname, "filename") == 0)
     417              :         {
     418           81 :             *filename = defGetString(def);
     419           81 :             options = foreach_delete_current(options, lc);
     420           81 :             break;
     421              :         }
     422           81 :         else if (strcmp(def->defname, "program") == 0)
     423              :         {
     424            0 :             *filename = defGetString(def);
     425            0 :             *is_program = true;
     426            0 :             options = foreach_delete_current(options, lc);
     427            0 :             break;
     428              :         }
     429              :     }
     430              : 
     431              :     /*
     432              :      * The validator should have checked that filename or program was included
     433              :      * in the options, but check again, just in case.
     434              :      */
     435           81 :     if (*filename == NULL)
     436            0 :         elog(ERROR, "either filename or program is required for file_fdw foreign tables");
     437              : 
     438           81 :     *other_options = options;
     439           81 : }
     440              : 
     441              : /*
     442              :  * Retrieve per-column generic options from pg_attribute and construct a list
     443              :  * of DefElems representing them.
     444              :  *
     445              :  * At the moment we only have "force_not_null", and "force_null",
     446              :  * which should each be combined into a single DefElem listing all such
     447              :  * columns, since that's what COPY expects.
     448              :  */
     449              : static List *
     450           81 : get_file_fdw_attribute_options(Oid relid)
     451              : {
     452              :     Relation    rel;
     453              :     TupleDesc   tupleDesc;
     454              :     AttrNumber  natts;
     455              :     AttrNumber  attnum;
     456           81 :     List       *fnncolumns = NIL;
     457           81 :     List       *fncolumns = NIL;
     458              : 
     459           81 :     List       *options = NIL;
     460              : 
     461           81 :     rel = table_open(relid, AccessShareLock);
     462           81 :     tupleDesc = RelationGetDescr(rel);
     463           81 :     natts = tupleDesc->natts;
     464              : 
     465              :     /* Retrieve FDW options for all user-defined attributes. */
     466          255 :     for (attnum = 1; attnum <= natts; attnum++)
     467              :     {
     468          174 :         Form_pg_attribute attr = TupleDescAttr(tupleDesc, attnum - 1);
     469              :         List       *column_options;
     470              :         ListCell   *lc;
     471              : 
     472              :         /* Skip dropped attributes. */
     473          174 :         if (attr->attisdropped)
     474            0 :             continue;
     475              : 
     476          174 :         column_options = GetForeignColumnOptions(relid, attnum);
     477          190 :         foreach(lc, column_options)
     478              :         {
     479           16 :             DefElem    *def = (DefElem *) lfirst(lc);
     480              : 
     481           16 :             if (strcmp(def->defname, "force_not_null") == 0)
     482              :             {
     483            8 :                 if (defGetBoolean(def))
     484              :                 {
     485            4 :                     char       *attname = pstrdup(NameStr(attr->attname));
     486              : 
     487            4 :                     fnncolumns = lappend(fnncolumns, makeString(attname));
     488              :                 }
     489              :             }
     490            8 :             else if (strcmp(def->defname, "force_null") == 0)
     491              :             {
     492            8 :                 if (defGetBoolean(def))
     493              :                 {
     494            4 :                     char       *attname = pstrdup(NameStr(attr->attname));
     495              : 
     496            4 :                     fncolumns = lappend(fncolumns, makeString(attname));
     497              :                 }
     498              :             }
     499              :             /* maybe in future handle other column options here */
     500              :         }
     501              :     }
     502              : 
     503           81 :     table_close(rel, AccessShareLock);
     504              : 
     505              :     /*
     506              :      * Return DefElem only when some column(s) have force_not_null /
     507              :      * force_null options set
     508              :      */
     509           81 :     if (fnncolumns != NIL)
     510            4 :         options = lappend(options, makeDefElem("force_not_null", (Node *) fnncolumns, -1));
     511              : 
     512           81 :     if (fncolumns != NIL)
     513            4 :         options = lappend(options, makeDefElem("force_null", (Node *) fncolumns, -1));
     514              : 
     515           81 :     return options;
     516              : }
     517              : 
     518              : /*
     519              :  * fileGetForeignRelSize
     520              :  *      Obtain relation size estimates for a foreign table
     521              :  */
     522              : static void
     523           42 : fileGetForeignRelSize(PlannerInfo *root,
     524              :                       RelOptInfo *baserel,
     525              :                       Oid foreigntableid)
     526              : {
     527              :     FileFdwPlanState *fdw_private;
     528              : 
     529              :     /*
     530              :      * Fetch options.  We only need filename (or program) at this point, but
     531              :      * we might as well get everything and not need to re-fetch it later in
     532              :      * planning.
     533              :      */
     534           42 :     fdw_private = palloc_object(FileFdwPlanState);
     535           42 :     fileGetOptions(foreigntableid,
     536              :                    &fdw_private->filename,
     537              :                    &fdw_private->is_program,
     538              :                    &fdw_private->options);
     539           42 :     baserel->fdw_private = fdw_private;
     540              : 
     541              :     /* Estimate relation size */
     542           42 :     estimate_size(root, baserel, fdw_private);
     543           42 : }
     544              : 
     545              : /*
     546              :  * fileGetForeignPaths
     547              :  *      Create possible access paths for a scan on the foreign table
     548              :  *
     549              :  *      Currently we don't support any push-down feature, so there is only one
     550              :  *      possible access path, which simply returns all records in the order in
     551              :  *      the data file.
     552              :  */
     553              : static void
     554           42 : fileGetForeignPaths(PlannerInfo *root,
     555              :                     RelOptInfo *baserel,
     556              :                     Oid foreigntableid)
     557              : {
     558           42 :     FileFdwPlanState *fdw_private = (FileFdwPlanState *) baserel->fdw_private;
     559              :     Cost        startup_cost;
     560              :     Cost        total_cost;
     561              :     List       *columns;
     562           42 :     List       *coptions = NIL;
     563              : 
     564              :     /* Decide whether to selectively perform binary conversion */
     565           42 :     if (check_selective_binary_conversion(baserel,
     566              :                                           foreigntableid,
     567              :                                           &columns))
     568            5 :         coptions = list_make1(makeDefElem("convert_selectively",
     569              :                                           (Node *) columns, -1));
     570              : 
     571              :     /* Estimate costs */
     572           42 :     estimate_costs(root, baserel, fdw_private,
     573              :                    &startup_cost, &total_cost);
     574              : 
     575              :     /*
     576              :      * Create a ForeignPath node and add it as only possible path.  We use the
     577              :      * fdw_private list of the path to carry the convert_selectively option;
     578              :      * it will be propagated into the fdw_private list of the Plan node.
     579              :      *
     580              :      * We don't support pushing join clauses into the quals of this path, but
     581              :      * it could still have required parameterization due to LATERAL refs in
     582              :      * its tlist.
     583              :      */
     584           42 :     add_path(baserel, (Path *)
     585           42 :              create_foreignscan_path(root, baserel,
     586              :                                      NULL,  /* default pathtarget */
     587              :                                      baserel->rows,
     588              :                                      0,
     589              :                                      startup_cost,
     590              :                                      total_cost,
     591              :                                      NIL,   /* no pathkeys */
     592              :                                      baserel->lateral_relids,
     593              :                                      NULL,  /* no extra plan */
     594              :                                      NIL,   /* no fdw_restrictinfo list */
     595              :                                      coptions));
     596              : 
     597              :     /*
     598              :      * If data file was sorted, and we knew it somehow, we could insert
     599              :      * appropriate pathkeys into the ForeignPath node to tell the planner
     600              :      * that.
     601              :      */
     602           42 : }
     603              : 
     604              : /*
     605              :  * fileGetForeignPlan
     606              :  *      Create a ForeignScan plan node for scanning the foreign table
     607              :  */
     608              : static ForeignScan *
     609           42 : fileGetForeignPlan(PlannerInfo *root,
     610              :                    RelOptInfo *baserel,
     611              :                    Oid foreigntableid,
     612              :                    ForeignPath *best_path,
     613              :                    List *tlist,
     614              :                    List *scan_clauses,
     615              :                    Plan *outer_plan)
     616              : {
     617           42 :     Index       scan_relid = baserel->relid;
     618              : 
     619              :     /*
     620              :      * We have no native ability to evaluate restriction clauses, so we just
     621              :      * put all the scan_clauses into the plan node's qual list for the
     622              :      * executor to check.  So all we have to do here is strip RestrictInfo
     623              :      * nodes from the clauses and ignore pseudoconstants (which will be
     624              :      * handled elsewhere).
     625              :      */
     626           42 :     scan_clauses = extract_actual_clauses(scan_clauses, false);
     627              : 
     628              :     /* Create the ForeignScan node */
     629           42 :     return make_foreignscan(tlist,
     630              :                             scan_clauses,
     631              :                             scan_relid,
     632              :                             NIL,    /* no expressions to evaluate */
     633              :                             best_path->fdw_private,
     634              :                             NIL,    /* no custom tlist */
     635              :                             NIL,    /* no remote quals */
     636              :                             outer_plan);
     637              : }
     638              : 
     639              : /*
     640              :  * fileExplainForeignScan
     641              :  *      Produce extra output for EXPLAIN
     642              :  */
     643              : static void
     644            3 : fileExplainForeignScan(ForeignScanState *node, ExplainState *es)
     645              : {
     646              :     char       *filename;
     647              :     bool        is_program;
     648              :     List       *options;
     649              : 
     650              :     /* Fetch options --- we only need filename and is_program at this point */
     651            3 :     fileGetOptions(RelationGetRelid(node->ss.ss_currentRelation),
     652              :                    &filename, &is_program, &options);
     653              : 
     654            3 :     if (is_program)
     655            0 :         ExplainPropertyText("Foreign Program", filename, es);
     656              :     else
     657            3 :         ExplainPropertyText("Foreign File", filename, es);
     658              : 
     659              :     /* Suppress file size if we're not showing cost details */
     660            3 :     if (es->costs)
     661              :     {
     662              :         struct stat stat_buf;
     663              : 
     664            0 :         if (!is_program &&
     665            0 :             stat(filename, &stat_buf) == 0)
     666            0 :             ExplainPropertyInteger("Foreign File Size", "b",
     667            0 :                                    (int64) stat_buf.st_size, es);
     668              :     }
     669            3 : }
     670              : 
     671              : /*
     672              :  * fileBeginForeignScan
     673              :  *      Initiate access to the file by creating CopyState
     674              :  */
     675              : static void
     676           37 : fileBeginForeignScan(ForeignScanState *node, int eflags)
     677              : {
     678           37 :     ForeignScan *plan = (ForeignScan *) node->ss.ps.plan;
     679              :     char       *filename;
     680              :     bool        is_program;
     681              :     List       *options;
     682              :     CopyFromState cstate;
     683              :     FileFdwExecutionState *festate;
     684              : 
     685              :     /*
     686              :      * Do nothing in EXPLAIN (no ANALYZE) case.  node->fdw_state stays NULL.
     687              :      */
     688           37 :     if (eflags & EXEC_FLAG_EXPLAIN_ONLY)
     689            3 :         return;
     690              : 
     691              :     /* Fetch options of foreign table */
     692           34 :     fileGetOptions(RelationGetRelid(node->ss.ss_currentRelation),
     693              :                    &filename, &is_program, &options);
     694              : 
     695              :     /* Add any options from the plan (currently only convert_selectively) */
     696           34 :     options = list_concat(options, plan->fdw_private);
     697              : 
     698              :     /*
     699              :      * Create CopyState from FDW options.  We always acquire all columns, so
     700              :      * as to match the expected ScanTupleSlot signature.
     701              :      */
     702           34 :     cstate = BeginCopyFrom(NULL,
     703              :                            node->ss.ss_currentRelation,
     704              :                            NULL,
     705              :                            filename,
     706              :                            is_program,
     707              :                            NULL,
     708              :                            NIL,
     709              :                            options);
     710              : 
     711              :     /*
     712              :      * Save state in node->fdw_state.  We must save enough information to call
     713              :      * BeginCopyFrom() again.
     714              :      */
     715           33 :     festate = palloc_object(FileFdwExecutionState);
     716           33 :     festate->filename = filename;
     717           33 :     festate->is_program = is_program;
     718           33 :     festate->options = options;
     719           33 :     festate->cstate = cstate;
     720              : 
     721           33 :     node->fdw_state = festate;
     722              : }
     723              : 
     724              : /*
     725              :  * fileIterateForeignScan
     726              :  *      Read next record from the data file and store it into the
     727              :  *      ScanTupleSlot as a virtual tuple
     728              :  */
     729              : static TupleTableSlot *
     730          127 : fileIterateForeignScan(ForeignScanState *node)
     731              : {
     732          127 :     FileFdwExecutionState *festate = (FileFdwExecutionState *) node->fdw_state;
     733          127 :     EState     *estate = CreateExecutorState();
     734              :     ExprContext *econtext;
     735          127 :     MemoryContext oldcontext = CurrentMemoryContext;
     736          127 :     TupleTableSlot *slot = node->ss.ss_ScanTupleSlot;
     737          127 :     CopyFromState cstate = festate->cstate;
     738              :     ErrorContextCallback errcallback;
     739              : 
     740              :     /* Set up callback to identify error line number. */
     741          127 :     errcallback.callback = CopyFromErrorCallback;
     742          127 :     errcallback.arg = cstate;
     743          127 :     errcallback.previous = error_context_stack;
     744          127 :     error_context_stack = &errcallback;
     745              : 
     746              :     /*
     747              :      * We pass ExprContext because there might be a use of the DEFAULT option
     748              :      * in COPY FROM, so we may need to evaluate default expressions.
     749              :      */
     750          127 :     econtext = GetPerTupleExprContext(estate);
     751              : 
     752          134 : retry:
     753              : 
     754              :     /*
     755              :      * DEFAULT expressions need to be evaluated in a per-tuple context, so
     756              :      * switch in case we are doing that.
     757              :      */
     758          134 :     MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));
     759              : 
     760              :     /*
     761              :      * The protocol for loading a virtual tuple into a slot is first
     762              :      * ExecClearTuple, then fill the values/isnull arrays, then
     763              :      * ExecStoreVirtualTuple.  If we don't find another row in the file, we
     764              :      * just skip the last step, leaving the slot empty as required.
     765              :      *
     766              :      */
     767          134 :     ExecClearTuple(slot);
     768              : 
     769          134 :     if (NextCopyFrom(cstate, econtext, slot->tts_values, slot->tts_isnull))
     770              :     {
     771          100 :         if (cstate->opts.on_error == COPY_ON_ERROR_IGNORE &&
     772           16 :             cstate->escontext->error_occurred)
     773              :         {
     774              :             /*
     775              :              * Soft error occurred, skip this tuple and just make
     776              :              * ErrorSaveContext ready for the next NextCopyFrom. Since we
     777              :              * don't set details_wanted and error_data is not to be filled,
     778              :              * just resetting error_occurred is enough.
     779              :              */
     780            8 :             cstate->escontext->error_occurred = false;
     781              : 
     782              :             /* Switch back to original memory context */
     783            8 :             MemoryContextSwitchTo(oldcontext);
     784              : 
     785              :             /*
     786              :              * Make sure we are interruptible while repeatedly calling
     787              :              * NextCopyFrom() until no soft error occurs.
     788              :              */
     789            8 :             CHECK_FOR_INTERRUPTS();
     790              : 
     791              :             /*
     792              :              * Reset the per-tuple exprcontext, to clean-up after expression
     793              :              * evaluations etc.
     794              :              */
     795            8 :             ResetPerTupleExprContext(estate);
     796              : 
     797            8 :             if (cstate->opts.reject_limit > 0 &&
     798            4 :                 cstate->num_errors > cstate->opts.reject_limit)
     799            1 :                 ereport(ERROR,
     800              :                         (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
     801              :                          errmsg("skipped more than REJECT_LIMIT (%" PRId64 ") rows due to data type incompatibility",
     802              :                                 cstate->opts.reject_limit)));
     803              : 
     804              :             /* Repeat NextCopyFrom() until no soft error occurs */
     805            7 :             goto retry;
     806              :         }
     807              : 
     808           92 :         ExecStoreVirtualTuple(slot);
     809              :     }
     810              : 
     811              :     /* Switch back to original memory context */
     812          124 :     MemoryContextSwitchTo(oldcontext);
     813              : 
     814              :     /* Remove error callback. */
     815          124 :     error_context_stack = errcallback.previous;
     816              : 
     817          124 :     return slot;
     818              : }
     819              : 
     820              : /*
     821              :  * fileReScanForeignScan
     822              :  *      Rescan table, possibly with new parameters
     823              :  */
     824              : static void
     825            3 : fileReScanForeignScan(ForeignScanState *node)
     826              : {
     827            3 :     FileFdwExecutionState *festate = (FileFdwExecutionState *) node->fdw_state;
     828              : 
     829            3 :     EndCopyFrom(festate->cstate);
     830              : 
     831            6 :     festate->cstate = BeginCopyFrom(NULL,
     832              :                                     node->ss.ss_currentRelation,
     833              :                                     NULL,
     834            3 :                                     festate->filename,
     835            3 :                                     festate->is_program,
     836              :                                     NULL,
     837              :                                     NIL,
     838              :                                     festate->options);
     839            3 : }
     840              : 
     841              : /*
     842              :  * fileEndForeignScan
     843              :  *      Finish scanning foreign table and dispose objects used for this scan
     844              :  */
     845              : static void
     846           33 : fileEndForeignScan(ForeignScanState *node)
     847              : {
     848           33 :     FileFdwExecutionState *festate = (FileFdwExecutionState *) node->fdw_state;
     849              : 
     850              :     /* if festate is NULL, we are in EXPLAIN; nothing to do */
     851           33 :     if (!festate)
     852            3 :         return;
     853              : 
     854           30 :     if (festate->cstate->opts.on_error == COPY_ON_ERROR_IGNORE &&
     855            3 :         festate->cstate->num_errors > 0 &&
     856            3 :         festate->cstate->opts.log_verbosity >= COPY_LOG_VERBOSITY_DEFAULT)
     857            1 :         ereport(NOTICE,
     858              :                 errmsg_plural("%" PRIu64 " row was skipped due to data type incompatibility",
     859              :                               "%" PRIu64 " rows were skipped due to data type incompatibility",
     860              :                               festate->cstate->num_errors,
     861              :                               festate->cstate->num_errors));
     862              : 
     863           30 :     EndCopyFrom(festate->cstate);
     864              : }
     865              : 
     866              : /*
     867              :  * fileAnalyzeForeignTable
     868              :  *      Test whether analyzing this foreign table is supported
     869              :  */
     870              : static bool
     871            1 : fileAnalyzeForeignTable(Relation relation,
     872              :                         AcquireSampleRowsFunc *func,
     873              :                         BlockNumber *totalpages)
     874              : {
     875              :     char       *filename;
     876              :     bool        is_program;
     877              :     List       *options;
     878              :     struct stat stat_buf;
     879              : 
     880              :     /* Fetch options of foreign table */
     881            1 :     fileGetOptions(RelationGetRelid(relation), &filename, &is_program, &options);
     882              : 
     883              :     /*
     884              :      * If this is a program instead of a file, just return false to skip
     885              :      * analyzing the table.  We could run the program and collect stats on
     886              :      * whatever it currently returns, but it seems likely that in such cases
     887              :      * the output would be too volatile for the stats to be useful.  Maybe
     888              :      * there should be an option to enable doing this?
     889              :      */
     890            1 :     if (is_program)
     891            0 :         return false;
     892              : 
     893              :     /*
     894              :      * Get size of the file.  (XXX if we fail here, would it be better to just
     895              :      * return false to skip analyzing the table?)
     896              :      */
     897            1 :     if (stat(filename, &stat_buf) < 0)
     898            0 :         ereport(ERROR,
     899              :                 (errcode_for_file_access(),
     900              :                  errmsg("could not stat file \"%s\": %m",
     901              :                         filename)));
     902              : 
     903              :     /*
     904              :      * Convert size to pages.  Must return at least 1 so that we can tell
     905              :      * later on that pg_class.relpages is not default.
     906              :      */
     907            1 :     *totalpages = (stat_buf.st_size + (BLCKSZ - 1)) / BLCKSZ;
     908            1 :     if (*totalpages < 1)
     909            0 :         *totalpages = 1;
     910              : 
     911            1 :     *func = file_acquire_sample_rows;
     912              : 
     913            1 :     return true;
     914              : }
     915              : 
     916              : /*
     917              :  * fileIsForeignScanParallelSafe
     918              :  *      Reading a file, or external program, in a parallel worker should work
     919              :  *      just the same as reading it in the leader, so mark scans safe.
     920              :  */
     921              : static bool
     922           38 : fileIsForeignScanParallelSafe(PlannerInfo *root, RelOptInfo *rel,
     923              :                               RangeTblEntry *rte)
     924              : {
     925           38 :     return true;
     926              : }
     927              : 
     928              : /*
     929              :  * check_selective_binary_conversion
     930              :  *
     931              :  * Check to see if it's useful to convert only a subset of the file's columns
     932              :  * to binary.  If so, construct a list of the column names to be converted,
     933              :  * return that at *columns, and return true.  (Note that it's possible to
     934              :  * determine that no columns need be converted, for instance with a COUNT(*)
     935              :  * query.  So we can't use returning a NIL list to indicate failure.)
     936              :  */
     937              : static bool
     938           42 : check_selective_binary_conversion(RelOptInfo *baserel,
     939              :                                   Oid foreigntableid,
     940              :                                   List **columns)
     941              : {
     942              :     ForeignTable *table;
     943              :     ListCell   *lc;
     944              :     Relation    rel;
     945              :     TupleDesc   tupleDesc;
     946              :     int         attidx;
     947           42 :     Bitmapset  *attrs_used = NULL;
     948           42 :     bool        has_wholerow = false;
     949              :     int         numattrs;
     950              :     int         i;
     951              : 
     952           42 :     *columns = NIL;             /* default result */
     953              : 
     954              :     /*
     955              :      * Check format of the file.  If binary format, this is irrelevant.
     956              :      */
     957           42 :     table = GetForeignTable(foreigntableid);
     958           42 :     foreach(lc, table->options)
     959              :     {
     960           42 :         DefElem    *def = (DefElem *) lfirst(lc);
     961              : 
     962           42 :         if (strcmp(def->defname, "format") == 0)
     963              :         {
     964           42 :             char       *format = defGetString(def);
     965              : 
     966           42 :             if (strcmp(format, "binary") == 0)
     967            0 :                 return false;
     968           42 :             break;
     969              :         }
     970              :     }
     971              : 
     972              :     /* Collect all the attributes needed for joins or final output. */
     973           42 :     pull_varattnos((Node *) baserel->reltarget->exprs, baserel->relid,
     974              :                    &attrs_used);
     975              : 
     976              :     /* Add all the attributes used by restriction clauses. */
     977           50 :     foreach(lc, baserel->baserestrictinfo)
     978              :     {
     979            8 :         RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
     980              : 
     981            8 :         pull_varattnos((Node *) rinfo->clause, baserel->relid,
     982              :                        &attrs_used);
     983              :     }
     984              : 
     985              :     /* Convert attribute numbers to column names. */
     986           42 :     rel = table_open(foreigntableid, AccessShareLock);
     987           42 :     tupleDesc = RelationGetDescr(rel);
     988              : 
     989           42 :     attidx = -1;
     990          131 :     while ((attidx = bms_next_member(attrs_used, attidx)) >= 0)
     991              :     {
     992              :         /* attidx is zero-based, attnum is the normal attribute number */
     993           93 :         AttrNumber  attnum = attidx + FirstLowInvalidHeapAttributeNumber;
     994              : 
     995           93 :         if (attnum == 0)
     996              :         {
     997            4 :             has_wholerow = true;
     998            4 :             break;
     999              :         }
    1000              : 
    1001              :         /* Ignore system attributes. */
    1002           89 :         if (attnum < 0)
    1003           13 :             continue;
    1004              : 
    1005              :         /* Get user attributes. */
    1006           76 :         if (attnum > 0)
    1007              :         {
    1008           76 :             Form_pg_attribute attr = TupleDescAttr(tupleDesc, attnum - 1);
    1009           76 :             char       *attname = NameStr(attr->attname);
    1010              : 
    1011              :             /* Skip dropped attributes (probably shouldn't see any here). */
    1012           76 :             if (attr->attisdropped)
    1013            0 :                 continue;
    1014              : 
    1015              :             /*
    1016              :              * Skip generated columns (COPY won't accept them in the column
    1017              :              * list)
    1018              :              */
    1019           76 :             if (attr->attgenerated)
    1020            1 :                 continue;
    1021           75 :             *columns = lappend(*columns, makeString(pstrdup(attname)));
    1022              :         }
    1023              :     }
    1024              : 
    1025              :     /* Count non-dropped user attributes while we have the tupdesc. */
    1026           42 :     numattrs = 0;
    1027          132 :     for (i = 0; i < tupleDesc->natts; i++)
    1028              :     {
    1029           90 :         if (TupleDescCompactAttr(tupleDesc, i)->attisdropped)
    1030            0 :             continue;
    1031           90 :         numattrs++;
    1032              :     }
    1033              : 
    1034           42 :     table_close(rel, AccessShareLock);
    1035              : 
    1036              :     /* If there's a whole-row reference, fail: we need all the columns. */
    1037           42 :     if (has_wholerow)
    1038              :     {
    1039            4 :         *columns = NIL;
    1040            4 :         return false;
    1041              :     }
    1042              : 
    1043              :     /* If all the user attributes are needed, fail. */
    1044           38 :     if (numattrs == list_length(*columns))
    1045              :     {
    1046           33 :         *columns = NIL;
    1047           33 :         return false;
    1048              :     }
    1049              : 
    1050            5 :     return true;
    1051              : }
    1052              : 
    1053              : /*
    1054              :  * Estimate size of a foreign table.
    1055              :  *
    1056              :  * The main result is returned in baserel->rows.  We also set
    1057              :  * fdw_private->pages and fdw_private->ntuples for later use in the cost
    1058              :  * calculation.
    1059              :  */
    1060              : static void
    1061           42 : estimate_size(PlannerInfo *root, RelOptInfo *baserel,
    1062              :               FileFdwPlanState *fdw_private)
    1063              : {
    1064              :     struct stat stat_buf;
    1065              :     BlockNumber pages;
    1066              :     double      ntuples;
    1067              :     double      nrows;
    1068              : 
    1069              :     /*
    1070              :      * Get size of the file.  It might not be there at plan time, though, in
    1071              :      * which case we have to use a default estimate.  We also have to fall
    1072              :      * back to the default if using a program as the input.
    1073              :      */
    1074           42 :     if (fdw_private->is_program || stat(fdw_private->filename, &stat_buf) < 0)
    1075            0 :         stat_buf.st_size = 10 * BLCKSZ;
    1076              : 
    1077              :     /*
    1078              :      * Convert size to pages for use in I/O cost estimate later.
    1079              :      */
    1080           42 :     pages = (stat_buf.st_size + (BLCKSZ - 1)) / BLCKSZ;
    1081           42 :     if (pages < 1)
    1082            0 :         pages = 1;
    1083           42 :     fdw_private->pages = pages;
    1084              : 
    1085              :     /*
    1086              :      * Estimate the number of tuples in the file.
    1087              :      */
    1088           42 :     if (baserel->tuples >= 0 && baserel->pages > 0)
    1089            0 :     {
    1090              :         /*
    1091              :          * We have # of pages and # of tuples from pg_class (that is, from a
    1092              :          * previous ANALYZE), so compute a tuples-per-page estimate and scale
    1093              :          * that by the current file size.
    1094              :          */
    1095              :         double      density;
    1096              : 
    1097            0 :         density = baserel->tuples / (double) baserel->pages;
    1098            0 :         ntuples = clamp_row_est(density * (double) pages);
    1099              :     }
    1100              :     else
    1101              :     {
    1102              :         /*
    1103              :          * Otherwise we have to fake it.  We back into this estimate using the
    1104              :          * planner's idea of the relation width; which is bogus if not all
    1105              :          * columns are being read, not to mention that the text representation
    1106              :          * of a row probably isn't the same size as its internal
    1107              :          * representation.  Possibly we could do something better, but the
    1108              :          * real answer to anyone who complains is "ANALYZE" ...
    1109              :          */
    1110              :         int         tuple_width;
    1111              : 
    1112           42 :         tuple_width = MAXALIGN(baserel->reltarget->width) +
    1113              :             MAXALIGN(SizeofHeapTupleHeader);
    1114           42 :         ntuples = clamp_row_est((double) stat_buf.st_size /
    1115           42 :                                 (double) tuple_width);
    1116              :     }
    1117           42 :     fdw_private->ntuples = ntuples;
    1118              : 
    1119              :     /*
    1120              :      * Now estimate the number of rows returned by the scan after applying the
    1121              :      * baserestrictinfo quals.
    1122              :      */
    1123           42 :     nrows = ntuples *
    1124           42 :         clauselist_selectivity(root,
    1125              :                                baserel->baserestrictinfo,
    1126              :                                0,
    1127              :                                JOIN_INNER,
    1128              :                                NULL);
    1129              : 
    1130           42 :     nrows = clamp_row_est(nrows);
    1131              : 
    1132              :     /* Save the output-rows estimate for the planner */
    1133           42 :     baserel->rows = nrows;
    1134           42 : }
    1135              : 
    1136              : /*
    1137              :  * Estimate costs of scanning a foreign table.
    1138              :  *
    1139              :  * Results are returned in *startup_cost and *total_cost.
    1140              :  */
    1141              : static void
    1142           42 : estimate_costs(PlannerInfo *root, RelOptInfo *baserel,
    1143              :                FileFdwPlanState *fdw_private,
    1144              :                Cost *startup_cost, Cost *total_cost)
    1145              : {
    1146           42 :     BlockNumber pages = fdw_private->pages;
    1147           42 :     double      ntuples = fdw_private->ntuples;
    1148           42 :     Cost        run_cost = 0;
    1149              :     Cost        cpu_per_tuple;
    1150              : 
    1151              :     /*
    1152              :      * We estimate costs almost the same way as cost_seqscan(), thus assuming
    1153              :      * that I/O costs are equivalent to a regular table file of the same size.
    1154              :      * However, we take per-tuple CPU costs as 10x of a seqscan, to account
    1155              :      * for the cost of parsing records.
    1156              :      *
    1157              :      * In the case of a program source, this calculation is even more divorced
    1158              :      * from reality, but we have no good alternative; and it's not clear that
    1159              :      * the numbers we produce here matter much anyway, since there's only one
    1160              :      * access path for the rel.
    1161              :      */
    1162           42 :     run_cost += seq_page_cost * pages;
    1163              : 
    1164           42 :     *startup_cost = baserel->baserestrictcost.startup;
    1165           42 :     cpu_per_tuple = cpu_tuple_cost * 10 + baserel->baserestrictcost.per_tuple;
    1166           42 :     run_cost += cpu_per_tuple * ntuples;
    1167           42 :     *total_cost = *startup_cost + run_cost;
    1168           42 : }
    1169              : 
    1170              : /*
    1171              :  * file_acquire_sample_rows -- acquire a random sample of rows from the table
    1172              :  *
    1173              :  * Selected rows are returned in the caller-allocated array rows[],
    1174              :  * which must have at least targrows entries.
    1175              :  * The actual number of rows selected is returned as the function result.
    1176              :  * We also count the total number of rows in the file and return it into
    1177              :  * *totalrows.  Rows skipped due to on_error = 'ignore' are not included
    1178              :  * in this count.  Note that *totaldeadrows is always set to 0.
    1179              :  *
    1180              :  * Note that the returned list of rows is not always in order by physical
    1181              :  * position in the file.  Therefore, correlation estimates derived later
    1182              :  * may be meaningless, but it's OK because we don't use the estimates
    1183              :  * currently (the planner only pays attention to correlation for indexscans).
    1184              :  */
    1185              : static int
    1186            1 : file_acquire_sample_rows(Relation onerel, int elevel,
    1187              :                          HeapTuple *rows, int targrows,
    1188              :                          double *totalrows, double *totaldeadrows)
    1189              : {
    1190            1 :     int         numrows = 0;
    1191            1 :     double      rowstoskip = -1;    /* -1 means not set yet */
    1192              :     ReservoirStateData rstate;
    1193              :     TupleDesc   tupDesc;
    1194              :     Datum      *values;
    1195              :     bool       *nulls;
    1196              :     bool        found;
    1197              :     char       *filename;
    1198              :     bool        is_program;
    1199              :     List       *options;
    1200              :     CopyFromState cstate;
    1201              :     ErrorContextCallback errcallback;
    1202            1 :     MemoryContext oldcontext = CurrentMemoryContext;
    1203              :     MemoryContext tupcontext;
    1204              : 
    1205              :     Assert(onerel);
    1206              :     Assert(targrows > 0);
    1207              : 
    1208            1 :     tupDesc = RelationGetDescr(onerel);
    1209            1 :     values = (Datum *) palloc(tupDesc->natts * sizeof(Datum));
    1210            1 :     nulls = (bool *) palloc(tupDesc->natts * sizeof(bool));
    1211              : 
    1212              :     /* Fetch options of foreign table */
    1213            1 :     fileGetOptions(RelationGetRelid(onerel), &filename, &is_program, &options);
    1214              : 
    1215              :     /*
    1216              :      * Create CopyState from FDW options.
    1217              :      */
    1218            1 :     cstate = BeginCopyFrom(NULL, onerel, NULL, filename, is_program, NULL, NIL,
    1219              :                            options);
    1220              : 
    1221              :     /*
    1222              :      * Use per-tuple memory context to prevent leak of memory used to read
    1223              :      * rows from the file with Copy routines.
    1224              :      */
    1225            1 :     tupcontext = AllocSetContextCreate(CurrentMemoryContext,
    1226              :                                        "file_fdw temporary context",
    1227              :                                        ALLOCSET_DEFAULT_SIZES);
    1228              : 
    1229              :     /* Prepare for sampling rows */
    1230            1 :     reservoir_init_selection_state(&rstate, targrows);
    1231              : 
    1232              :     /* Set up callback to identify error line number. */
    1233            1 :     errcallback.callback = CopyFromErrorCallback;
    1234            1 :     errcallback.arg = cstate;
    1235            1 :     errcallback.previous = error_context_stack;
    1236            1 :     error_context_stack = &errcallback;
    1237              : 
    1238            1 :     *totalrows = 0;
    1239            1 :     *totaldeadrows = 0;
    1240              :     for (;;)
    1241              :     {
    1242              :         /* Check for user-requested abort or sleep */
    1243            5 :         vacuum_delay_point(true);
    1244              : 
    1245              :         /* Fetch next row */
    1246            5 :         MemoryContextReset(tupcontext);
    1247            5 :         MemoryContextSwitchTo(tupcontext);
    1248              : 
    1249            5 :         found = NextCopyFrom(cstate, NULL, values, nulls);
    1250              : 
    1251            5 :         MemoryContextSwitchTo(oldcontext);
    1252              : 
    1253            5 :         if (!found)
    1254            1 :             break;
    1255              : 
    1256            4 :         if (cstate->opts.on_error == COPY_ON_ERROR_IGNORE &&
    1257            4 :             cstate->escontext->error_occurred)
    1258              :         {
    1259              :             /*
    1260              :              * Soft error occurred, skip this tuple and just make
    1261              :              * ErrorSaveContext ready for the next NextCopyFrom. Since we
    1262              :              * don't set details_wanted and error_data is not to be filled,
    1263              :              * just resetting error_occurred is enough.
    1264              :              */
    1265            2 :             cstate->escontext->error_occurred = false;
    1266              : 
    1267              :             /* Repeat NextCopyFrom() until no soft error occurs */
    1268            2 :             continue;
    1269              :         }
    1270              : 
    1271              :         /*
    1272              :          * The first targrows sample rows are simply copied into the
    1273              :          * reservoir.  Then we start replacing tuples in the sample until we
    1274              :          * reach the end of the relation. This algorithm is from Jeff Vitter's
    1275              :          * paper (see more info in commands/analyze.c).
    1276              :          */
    1277            2 :         if (numrows < targrows)
    1278              :         {
    1279            2 :             rows[numrows++] = heap_form_tuple(tupDesc, values, nulls);
    1280              :         }
    1281              :         else
    1282              :         {
    1283              :             /*
    1284              :              * t in Vitter's paper is the number of records already processed.
    1285              :              * If we need to compute a new S value, we must use the
    1286              :              * not-yet-incremented value of totalrows as t.
    1287              :              */
    1288            0 :             if (rowstoskip < 0)
    1289            0 :                 rowstoskip = reservoir_get_next_S(&rstate, *totalrows, targrows);
    1290              : 
    1291            0 :             if (rowstoskip <= 0)
    1292              :             {
    1293              :                 /*
    1294              :                  * Found a suitable tuple, so save it, replacing one old tuple
    1295              :                  * at random
    1296              :                  */
    1297            0 :                 int         k = (int) (targrows * sampler_random_fract(&rstate.randstate));
    1298              : 
    1299              :                 Assert(k >= 0 && k < targrows);
    1300            0 :                 heap_freetuple(rows[k]);
    1301            0 :                 rows[k] = heap_form_tuple(tupDesc, values, nulls);
    1302              :             }
    1303              : 
    1304            0 :             rowstoskip -= 1;
    1305              :         }
    1306              : 
    1307            2 :         *totalrows += 1;
    1308              :     }
    1309              : 
    1310              :     /* Remove error callback. */
    1311            1 :     error_context_stack = errcallback.previous;
    1312              : 
    1313              :     /* Clean up. */
    1314            1 :     MemoryContextDelete(tupcontext);
    1315              : 
    1316            1 :     if (cstate->opts.on_error == COPY_ON_ERROR_IGNORE &&
    1317            1 :         cstate->num_errors > 0 &&
    1318            1 :         cstate->opts.log_verbosity >= COPY_LOG_VERBOSITY_DEFAULT)
    1319            0 :         ereport(NOTICE,
    1320              :                 errmsg_plural("%" PRIu64 " row was skipped due to data type incompatibility",
    1321              :                               "%" PRIu64 " rows were skipped due to data type incompatibility",
    1322              :                               cstate->num_errors,
    1323              :                               cstate->num_errors));
    1324              : 
    1325            1 :     EndCopyFrom(cstate);
    1326              : 
    1327            1 :     pfree(values);
    1328            1 :     pfree(nulls);
    1329              : 
    1330              :     /*
    1331              :      * Emit some interesting relation info
    1332              :      */
    1333            1 :     ereport(elevel,
    1334              :             (errmsg("\"%s\": file contains %.0f rows; "
    1335              :                     "%d rows in sample",
    1336              :                     RelationGetRelationName(onerel),
    1337              :                     *totalrows, numrows)));
    1338              : 
    1339            1 :     return numrows;
    1340              : }
        

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