LCOV - code coverage report
Current view: top level - src/backend/optimizer/path - allpaths.c (source / functions) Hit Total Coverage
Test: PostgreSQL 17devel Lines: 1048 1110 94.4 %
Date: 2024-05-19 07:11:14 Functions: 49 49 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * allpaths.c
       4             :  *    Routines to find possible search paths for processing a query
       5             :  *
       6             :  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
       7             :  * Portions Copyright (c) 1994, Regents of the University of California
       8             :  *
       9             :  *
      10             :  * IDENTIFICATION
      11             :  *    src/backend/optimizer/path/allpaths.c
      12             :  *
      13             :  *-------------------------------------------------------------------------
      14             :  */
      15             : 
      16             : #include "postgres.h"
      17             : 
      18             : #include <limits.h>
      19             : #include <math.h>
      20             : 
      21             : #include "access/sysattr.h"
      22             : #include "access/tsmapi.h"
      23             : #include "catalog/pg_class.h"
      24             : #include "catalog/pg_operator.h"
      25             : #include "catalog/pg_proc.h"
      26             : #include "foreign/fdwapi.h"
      27             : #include "miscadmin.h"
      28             : #include "nodes/makefuncs.h"
      29             : #include "nodes/nodeFuncs.h"
      30             : #include "nodes/supportnodes.h"
      31             : #ifdef OPTIMIZER_DEBUG
      32             : #include "nodes/print.h"
      33             : #endif
      34             : #include "optimizer/appendinfo.h"
      35             : #include "optimizer/clauses.h"
      36             : #include "optimizer/cost.h"
      37             : #include "optimizer/geqo.h"
      38             : #include "optimizer/optimizer.h"
      39             : #include "optimizer/pathnode.h"
      40             : #include "optimizer/paths.h"
      41             : #include "optimizer/plancat.h"
      42             : #include "optimizer/planner.h"
      43             : #include "optimizer/tlist.h"
      44             : #include "parser/parse_clause.h"
      45             : #include "parser/parsetree.h"
      46             : #include "partitioning/partbounds.h"
      47             : #include "port/pg_bitutils.h"
      48             : #include "rewrite/rewriteManip.h"
      49             : #include "utils/lsyscache.h"
      50             : 
      51             : 
      52             : /* Bitmask flags for pushdown_safety_info.unsafeFlags */
      53             : #define UNSAFE_HAS_VOLATILE_FUNC        (1 << 0)
      54             : #define UNSAFE_HAS_SET_FUNC             (1 << 1)
      55             : #define UNSAFE_NOTIN_DISTINCTON_CLAUSE  (1 << 2)
      56             : #define UNSAFE_NOTIN_PARTITIONBY_CLAUSE (1 << 3)
      57             : #define UNSAFE_TYPE_MISMATCH            (1 << 4)
      58             : 
      59             : /* results of subquery_is_pushdown_safe */
      60             : typedef struct pushdown_safety_info
      61             : {
      62             :     unsigned char *unsafeFlags; /* bitmask of reasons why this target list
      63             :                                  * column is unsafe for qual pushdown, or 0 if
      64             :                                  * no reason. */
      65             :     bool        unsafeVolatile; /* don't push down volatile quals */
      66             :     bool        unsafeLeaky;    /* don't push down leaky quals */
      67             : } pushdown_safety_info;
      68             : 
      69             : /* Return type for qual_is_pushdown_safe */
      70             : typedef enum pushdown_safe_type
      71             : {
      72             :     PUSHDOWN_UNSAFE,            /* unsafe to push qual into subquery */
      73             :     PUSHDOWN_SAFE,              /* safe to push qual into subquery */
      74             :     PUSHDOWN_WINDOWCLAUSE_RUNCOND,  /* unsafe, but may work as WindowClause
      75             :                                      * run condition */
      76             : } pushdown_safe_type;
      77             : 
      78             : /* These parameters are set by GUC */
      79             : bool        enable_geqo = false;    /* just in case GUC doesn't set it */
      80             : int         geqo_threshold;
      81             : int         min_parallel_table_scan_size;
      82             : int         min_parallel_index_scan_size;
      83             : 
      84             : /* Hook for plugins to get control in set_rel_pathlist() */
      85             : set_rel_pathlist_hook_type set_rel_pathlist_hook = NULL;
      86             : 
      87             : /* Hook for plugins to replace standard_join_search() */
      88             : join_search_hook_type join_search_hook = NULL;
      89             : 
      90             : 
      91             : static void set_base_rel_consider_startup(PlannerInfo *root);
      92             : static void set_base_rel_sizes(PlannerInfo *root);
      93             : static void set_base_rel_pathlists(PlannerInfo *root);
      94             : static void set_rel_size(PlannerInfo *root, RelOptInfo *rel,
      95             :                          Index rti, RangeTblEntry *rte);
      96             : static void set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
      97             :                              Index rti, RangeTblEntry *rte);
      98             : static void set_plain_rel_size(PlannerInfo *root, RelOptInfo *rel,
      99             :                                RangeTblEntry *rte);
     100             : static void create_plain_partial_paths(PlannerInfo *root, RelOptInfo *rel);
     101             : static void set_rel_consider_parallel(PlannerInfo *root, RelOptInfo *rel,
     102             :                                       RangeTblEntry *rte);
     103             : static void set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
     104             :                                    RangeTblEntry *rte);
     105             : static void set_tablesample_rel_size(PlannerInfo *root, RelOptInfo *rel,
     106             :                                      RangeTblEntry *rte);
     107             : static void set_tablesample_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
     108             :                                          RangeTblEntry *rte);
     109             : static void set_foreign_size(PlannerInfo *root, RelOptInfo *rel,
     110             :                              RangeTblEntry *rte);
     111             : static void set_foreign_pathlist(PlannerInfo *root, RelOptInfo *rel,
     112             :                                  RangeTblEntry *rte);
     113             : static void set_append_rel_size(PlannerInfo *root, RelOptInfo *rel,
     114             :                                 Index rti, RangeTblEntry *rte);
     115             : static void set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
     116             :                                     Index rti, RangeTblEntry *rte);
     117             : static void generate_orderedappend_paths(PlannerInfo *root, RelOptInfo *rel,
     118             :                                          List *live_childrels,
     119             :                                          List *all_child_pathkeys);
     120             : static Path *get_cheapest_parameterized_child_path(PlannerInfo *root,
     121             :                                                    RelOptInfo *rel,
     122             :                                                    Relids required_outer);
     123             : static void accumulate_append_subpath(Path *path,
     124             :                                       List **subpaths,
     125             :                                       List **special_subpaths);
     126             : static Path *get_singleton_append_subpath(Path *path);
     127             : static void set_dummy_rel_pathlist(RelOptInfo *rel);
     128             : static void set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel,
     129             :                                   Index rti, RangeTblEntry *rte);
     130             : static void set_function_pathlist(PlannerInfo *root, RelOptInfo *rel,
     131             :                                   RangeTblEntry *rte);
     132             : static void set_values_pathlist(PlannerInfo *root, RelOptInfo *rel,
     133             :                                 RangeTblEntry *rte);
     134             : static void set_tablefunc_pathlist(PlannerInfo *root, RelOptInfo *rel,
     135             :                                    RangeTblEntry *rte);
     136             : static void set_cte_pathlist(PlannerInfo *root, RelOptInfo *rel,
     137             :                              RangeTblEntry *rte);
     138             : static void set_namedtuplestore_pathlist(PlannerInfo *root, RelOptInfo *rel,
     139             :                                          RangeTblEntry *rte);
     140             : static void set_result_pathlist(PlannerInfo *root, RelOptInfo *rel,
     141             :                                 RangeTblEntry *rte);
     142             : static void set_worktable_pathlist(PlannerInfo *root, RelOptInfo *rel,
     143             :                                    RangeTblEntry *rte);
     144             : static RelOptInfo *make_rel_from_joinlist(PlannerInfo *root, List *joinlist);
     145             : static bool subquery_is_pushdown_safe(Query *subquery, Query *topquery,
     146             :                                       pushdown_safety_info *safetyInfo);
     147             : static bool recurse_pushdown_safe(Node *setOp, Query *topquery,
     148             :                                   pushdown_safety_info *safetyInfo);
     149             : static void check_output_expressions(Query *subquery,
     150             :                                      pushdown_safety_info *safetyInfo);
     151             : static void compare_tlist_datatypes(List *tlist, List *colTypes,
     152             :                                     pushdown_safety_info *safetyInfo);
     153             : static bool targetIsInAllPartitionLists(TargetEntry *tle, Query *query);
     154             : static pushdown_safe_type qual_is_pushdown_safe(Query *subquery, Index rti,
     155             :                                                 RestrictInfo *rinfo,
     156             :                                                 pushdown_safety_info *safetyInfo);
     157             : static void subquery_push_qual(Query *subquery,
     158             :                                RangeTblEntry *rte, Index rti, Node *qual);
     159             : static void recurse_push_qual(Node *setOp, Query *topquery,
     160             :                               RangeTblEntry *rte, Index rti, Node *qual);
     161             : static void remove_unused_subquery_outputs(Query *subquery, RelOptInfo *rel,
     162             :                                            Bitmapset *extra_used_attrs);
     163             : 
     164             : 
     165             : /*
     166             :  * make_one_rel
     167             :  *    Finds all possible access paths for executing a query, returning a
     168             :  *    single rel that represents the join of all base rels in the query.
     169             :  */
     170             : RelOptInfo *
     171      266402 : make_one_rel(PlannerInfo *root, List *joinlist)
     172             : {
     173             :     RelOptInfo *rel;
     174             :     Index       rti;
     175             :     double      total_pages;
     176             : 
     177             :     /* Mark base rels as to whether we care about fast-start plans */
     178      266402 :     set_base_rel_consider_startup(root);
     179             : 
     180             :     /*
     181             :      * Compute size estimates and consider_parallel flags for each base rel.
     182             :      */
     183      266402 :     set_base_rel_sizes(root);
     184             : 
     185             :     /*
     186             :      * We should now have size estimates for every actual table involved in
     187             :      * the query, and we also know which if any have been deleted from the
     188             :      * query by join removal, pruned by partition pruning, or eliminated by
     189             :      * constraint exclusion.  So we can now compute total_table_pages.
     190             :      *
     191             :      * Note that appendrels are not double-counted here, even though we don't
     192             :      * bother to distinguish RelOptInfos for appendrel parents, because the
     193             :      * parents will have pages = 0.
     194             :      *
     195             :      * XXX if a table is self-joined, we will count it once per appearance,
     196             :      * which perhaps is the wrong thing ... but that's not completely clear,
     197             :      * and detecting self-joins here is difficult, so ignore it for now.
     198             :      */
     199      266374 :     total_pages = 0;
     200      803806 :     for (rti = 1; rti < root->simple_rel_array_size; rti++)
     201             :     {
     202      537432 :         RelOptInfo *brel = root->simple_rel_array[rti];
     203             : 
     204             :         /* there may be empty slots corresponding to non-baserel RTEs */
     205      537432 :         if (brel == NULL)
     206      121960 :             continue;
     207             : 
     208             :         Assert(brel->relid == rti); /* sanity check on array */
     209             : 
     210      415472 :         if (IS_DUMMY_REL(brel))
     211        1078 :             continue;
     212             : 
     213      414394 :         if (IS_SIMPLE_REL(brel))
     214      414394 :             total_pages += (double) brel->pages;
     215             :     }
     216      266374 :     root->total_table_pages = total_pages;
     217             : 
     218             :     /*
     219             :      * Generate access paths for each base rel.
     220             :      */
     221      266374 :     set_base_rel_pathlists(root);
     222             : 
     223             :     /*
     224             :      * Generate access paths for the entire join tree.
     225             :      */
     226      266374 :     rel = make_rel_from_joinlist(root, joinlist);
     227             : 
     228             :     /*
     229             :      * The result should join all and only the query's base + outer-join rels.
     230             :      */
     231             :     Assert(bms_equal(rel->relids, root->all_query_rels));
     232             : 
     233      266372 :     return rel;
     234             : }
     235             : 
     236             : /*
     237             :  * set_base_rel_consider_startup
     238             :  *    Set the consider_[param_]startup flags for each base-relation entry.
     239             :  *
     240             :  * For the moment, we only deal with consider_param_startup here; because the
     241             :  * logic for consider_startup is pretty trivial and is the same for every base
     242             :  * relation, we just let build_simple_rel() initialize that flag correctly to
     243             :  * start with.  If that logic ever gets more complicated it would probably
     244             :  * be better to move it here.
     245             :  */
     246             : static void
     247      266402 : set_base_rel_consider_startup(PlannerInfo *root)
     248             : {
     249             :     /*
     250             :      * Since parameterized paths can only be used on the inside of a nestloop
     251             :      * join plan, there is usually little value in considering fast-start
     252             :      * plans for them.  However, for relations that are on the RHS of a SEMI
     253             :      * or ANTI join, a fast-start plan can be useful because we're only going
     254             :      * to care about fetching one tuple anyway.
     255             :      *
     256             :      * To minimize growth of planning time, we currently restrict this to
     257             :      * cases where the RHS is a single base relation, not a join; there is no
     258             :      * provision for consider_param_startup to get set at all on joinrels.
     259             :      * Also we don't worry about appendrels.  costsize.c's costing rules for
     260             :      * nestloop semi/antijoins don't consider such cases either.
     261             :      */
     262             :     ListCell   *lc;
     263             : 
     264      302134 :     foreach(lc, root->join_info_list)
     265             :     {
     266       35732 :         SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(lc);
     267             :         int         varno;
     268             : 
     269       40794 :         if ((sjinfo->jointype == JOIN_SEMI || sjinfo->jointype == JOIN_ANTI) &&
     270        5062 :             bms_get_singleton_member(sjinfo->syn_righthand, &varno))
     271             :         {
     272        4892 :             RelOptInfo *rel = find_base_rel(root, varno);
     273             : 
     274        4892 :             rel->consider_param_startup = true;
     275             :         }
     276             :     }
     277      266402 : }
     278             : 
     279             : /*
     280             :  * set_base_rel_sizes
     281             :  *    Set the size estimates (rows and widths) for each base-relation entry.
     282             :  *    Also determine whether to consider parallel paths for base relations.
     283             :  *
     284             :  * We do this in a separate pass over the base rels so that rowcount
     285             :  * estimates are available for parameterized path generation, and also so
     286             :  * that each rel's consider_parallel flag is set correctly before we begin to
     287             :  * generate paths.
     288             :  */
     289             : static void
     290      266402 : set_base_rel_sizes(PlannerInfo *root)
     291             : {
     292             :     Index       rti;
     293             : 
     294      803836 :     for (rti = 1; rti < root->simple_rel_array_size; rti++)
     295             :     {
     296      537462 :         RelOptInfo *rel = root->simple_rel_array[rti];
     297             :         RangeTblEntry *rte;
     298             : 
     299             :         /* there may be empty slots corresponding to non-baserel RTEs */
     300      537462 :         if (rel == NULL)
     301      121962 :             continue;
     302             : 
     303             :         Assert(rel->relid == rti);   /* sanity check on array */
     304             : 
     305             :         /* ignore RTEs that are "other rels" */
     306      415500 :         if (rel->reloptkind != RELOPT_BASEREL)
     307       42490 :             continue;
     308             : 
     309      373010 :         rte = root->simple_rte_array[rti];
     310             : 
     311             :         /*
     312             :          * If parallelism is allowable for this query in general, see whether
     313             :          * it's allowable for this rel in particular.  We have to do this
     314             :          * before set_rel_size(), because (a) if this rel is an inheritance
     315             :          * parent, set_append_rel_size() will use and perhaps change the rel's
     316             :          * consider_parallel flag, and (b) for some RTE types, set_rel_size()
     317             :          * goes ahead and makes paths immediately.
     318             :          */
     319      373010 :         if (root->glob->parallelModeOK)
     320      292360 :             set_rel_consider_parallel(root, rel, rte);
     321             : 
     322      373010 :         set_rel_size(root, rel, rti, rte);
     323             :     }
     324      266374 : }
     325             : 
     326             : /*
     327             :  * set_base_rel_pathlists
     328             :  *    Finds all paths available for scanning each base-relation entry.
     329             :  *    Sequential scan and any available indices are considered.
     330             :  *    Each useful path is attached to its relation's 'pathlist' field.
     331             :  */
     332             : static void
     333      266374 : set_base_rel_pathlists(PlannerInfo *root)
     334             : {
     335             :     Index       rti;
     336             : 
     337      803806 :     for (rti = 1; rti < root->simple_rel_array_size; rti++)
     338             :     {
     339      537432 :         RelOptInfo *rel = root->simple_rel_array[rti];
     340             : 
     341             :         /* there may be empty slots corresponding to non-baserel RTEs */
     342      537432 :         if (rel == NULL)
     343      121960 :             continue;
     344             : 
     345             :         Assert(rel->relid == rti);   /* sanity check on array */
     346             : 
     347             :         /* ignore RTEs that are "other rels" */
     348      415472 :         if (rel->reloptkind != RELOPT_BASEREL)
     349       42490 :             continue;
     350             : 
     351      372982 :         set_rel_pathlist(root, rel, rti, root->simple_rte_array[rti]);
     352             :     }
     353      266374 : }
     354             : 
     355             : /*
     356             :  * set_rel_size
     357             :  *    Set size estimates for a base relation
     358             :  */
     359             : static void
     360      415280 : set_rel_size(PlannerInfo *root, RelOptInfo *rel,
     361             :              Index rti, RangeTblEntry *rte)
     362             : {
     363      788290 :     if (rel->reloptkind == RELOPT_BASEREL &&
     364      373010 :         relation_excluded_by_constraints(root, rel, rte))
     365             :     {
     366             :         /*
     367             :          * We proved we don't need to scan the rel via constraint exclusion,
     368             :          * so set up a single dummy path for it.  Here we only check this for
     369             :          * regular baserels; if it's an otherrel, CE was already checked in
     370             :          * set_append_rel_size().
     371             :          *
     372             :          * In this case, we go ahead and set up the relation's path right away
     373             :          * instead of leaving it for set_rel_pathlist to do.  This is because
     374             :          * we don't have a convention for marking a rel as dummy except by
     375             :          * assigning a dummy path to it.
     376             :          */
     377         450 :         set_dummy_rel_pathlist(rel);
     378             :     }
     379      414830 :     else if (rte->inh)
     380             :     {
     381             :         /* It's an "append relation", process accordingly */
     382       20062 :         set_append_rel_size(root, rel, rti, rte);
     383             :     }
     384             :     else
     385             :     {
     386      394768 :         switch (rel->rtekind)
     387             :         {
     388      334608 :             case RTE_RELATION:
     389      334608 :                 if (rte->relkind == RELKIND_FOREIGN_TABLE)
     390             :                 {
     391             :                     /* Foreign table */
     392        2348 :                     set_foreign_size(root, rel, rte);
     393             :                 }
     394      332260 :                 else if (rte->relkind == RELKIND_PARTITIONED_TABLE)
     395             :                 {
     396             :                     /*
     397             :                      * We could get here if asked to scan a partitioned table
     398             :                      * with ONLY.  In that case we shouldn't scan any of the
     399             :                      * partitions, so mark it as a dummy rel.
     400             :                      */
     401          40 :                     set_dummy_rel_pathlist(rel);
     402             :                 }
     403      332220 :                 else if (rte->tablesample != NULL)
     404             :                 {
     405             :                     /* Sampled relation */
     406         300 :                     set_tablesample_rel_size(root, rel, rte);
     407             :                 }
     408             :                 else
     409             :                 {
     410             :                     /* Plain relation */
     411      331920 :                     set_plain_rel_size(root, rel, rte);
     412             :                 }
     413      334580 :                 break;
     414        7076 :             case RTE_SUBQUERY:
     415             : 
     416             :                 /*
     417             :                  * Subqueries don't support making a choice between
     418             :                  * parameterized and unparameterized paths, so just go ahead
     419             :                  * and build their paths immediately.
     420             :                  */
     421        7076 :                 set_subquery_pathlist(root, rel, rti, rte);
     422        7076 :                 break;
     423       38920 :             case RTE_FUNCTION:
     424       38920 :                 set_function_size_estimates(root, rel);
     425       38920 :                 break;
     426         548 :             case RTE_TABLEFUNC:
     427         548 :                 set_tablefunc_size_estimates(root, rel);
     428         548 :                 break;
     429        7654 :             case RTE_VALUES:
     430        7654 :                 set_values_size_estimates(root, rel);
     431        7654 :                 break;
     432        4014 :             case RTE_CTE:
     433             : 
     434             :                 /*
     435             :                  * CTEs don't support making a choice between parameterized
     436             :                  * and unparameterized paths, so just go ahead and build their
     437             :                  * paths immediately.
     438             :                  */
     439        4014 :                 if (rte->self_reference)
     440         806 :                     set_worktable_pathlist(root, rel, rte);
     441             :                 else
     442        3208 :                     set_cte_pathlist(root, rel, rte);
     443        4014 :                 break;
     444         442 :             case RTE_NAMEDTUPLESTORE:
     445             :                 /* Might as well just build the path immediately */
     446         442 :                 set_namedtuplestore_pathlist(root, rel, rte);
     447         442 :                 break;
     448        1506 :             case RTE_RESULT:
     449             :                 /* Might as well just build the path immediately */
     450        1506 :                 set_result_pathlist(root, rel, rte);
     451        1506 :                 break;
     452           0 :             default:
     453           0 :                 elog(ERROR, "unexpected rtekind: %d", (int) rel->rtekind);
     454             :                 break;
     455             :         }
     456             :     }
     457             : 
     458             :     /*
     459             :      * We insist that all non-dummy rels have a nonzero rowcount estimate.
     460             :      */
     461             :     Assert(rel->rows > 0 || IS_DUMMY_REL(rel));
     462      415250 : }
     463             : 
     464             : /*
     465             :  * set_rel_pathlist
     466             :  *    Build access paths for a base relation
     467             :  */
     468             : static void
     469      415298 : set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
     470             :                  Index rti, RangeTblEntry *rte)
     471             : {
     472      415298 :     if (IS_DUMMY_REL(rel))
     473             :     {
     474             :         /* We already proved the relation empty, so nothing more to do */
     475             :     }
     476      414358 :     else if (rte->inh)
     477             :     {
     478             :         /* It's an "append relation", process accordingly */
     479       19766 :         set_append_rel_pathlist(root, rel, rti, rte);
     480             :     }
     481             :     else
     482             :     {
     483      394592 :         switch (rel->rtekind)
     484             :         {
     485      334540 :             case RTE_RELATION:
     486      334540 :                 if (rte->relkind == RELKIND_FOREIGN_TABLE)
     487             :                 {
     488             :                     /* Foreign table */
     489        2344 :                     set_foreign_pathlist(root, rel, rte);
     490             :                 }
     491      332196 :                 else if (rte->tablesample != NULL)
     492             :                 {
     493             :                     /* Sampled relation */
     494         300 :                     set_tablesample_rel_pathlist(root, rel, rte);
     495             :                 }
     496             :                 else
     497             :                 {
     498             :                     /* Plain relation */
     499      331896 :                     set_plain_rel_pathlist(root, rel, rte);
     500             :                 }
     501      334540 :                 break;
     502        6968 :             case RTE_SUBQUERY:
     503             :                 /* Subquery --- fully handled during set_rel_size */
     504        6968 :                 break;
     505       38920 :             case RTE_FUNCTION:
     506             :                 /* RangeFunction */
     507       38920 :                 set_function_pathlist(root, rel, rte);
     508       38920 :                 break;
     509         548 :             case RTE_TABLEFUNC:
     510             :                 /* Table Function */
     511         548 :                 set_tablefunc_pathlist(root, rel, rte);
     512         548 :                 break;
     513        7654 :             case RTE_VALUES:
     514             :                 /* Values list */
     515        7654 :                 set_values_pathlist(root, rel, rte);
     516        7654 :                 break;
     517        4014 :             case RTE_CTE:
     518             :                 /* CTE reference --- fully handled during set_rel_size */
     519        4014 :                 break;
     520         442 :             case RTE_NAMEDTUPLESTORE:
     521             :                 /* tuplestore reference --- fully handled during set_rel_size */
     522         442 :                 break;
     523        1506 :             case RTE_RESULT:
     524             :                 /* simple Result --- fully handled during set_rel_size */
     525        1506 :                 break;
     526           0 :             default:
     527           0 :                 elog(ERROR, "unexpected rtekind: %d", (int) rel->rtekind);
     528             :                 break;
     529             :         }
     530             :     }
     531             : 
     532             :     /*
     533             :      * Allow a plugin to editorialize on the set of Paths for this base
     534             :      * relation.  It could add new paths (such as CustomPaths) by calling
     535             :      * add_path(), or add_partial_path() if parallel aware.  It could also
     536             :      * delete or modify paths added by the core code.
     537             :      */
     538      415298 :     if (set_rel_pathlist_hook)
     539           0 :         (*set_rel_pathlist_hook) (root, rel, rti, rte);
     540             : 
     541             :     /*
     542             :      * If this is a baserel, we should normally consider gathering any partial
     543             :      * paths we may have created for it.  We have to do this after calling the
     544             :      * set_rel_pathlist_hook, else it cannot add partial paths to be included
     545             :      * here.
     546             :      *
     547             :      * However, if this is an inheritance child, skip it.  Otherwise, we could
     548             :      * end up with a very large number of gather nodes, each trying to grab
     549             :      * its own pool of workers.  Instead, we'll consider gathering partial
     550             :      * paths for the parent appendrel.
     551             :      *
     552             :      * Also, if this is the topmost scan/join rel, we postpone gathering until
     553             :      * the final scan/join targetlist is available (see grouping_planner).
     554             :      */
     555      415298 :     if (rel->reloptkind == RELOPT_BASEREL &&
     556      372982 :         !bms_equal(rel->relids, root->all_query_rels))
     557      183378 :         generate_useful_gather_paths(root, rel, false);
     558             : 
     559             :     /* Now find the cheapest of the paths for this rel */
     560      415298 :     set_cheapest(rel);
     561             : 
     562             : #ifdef OPTIMIZER_DEBUG
     563             :     pprint(rel);
     564             : #endif
     565      415298 : }
     566             : 
     567             : /*
     568             :  * set_plain_rel_size
     569             :  *    Set size estimates for a plain relation (no subquery, no inheritance)
     570             :  */
     571             : static void
     572      331920 : set_plain_rel_size(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
     573             : {
     574             :     /*
     575             :      * Test any partial indexes of rel for applicability.  We must do this
     576             :      * first since partial unique indexes can affect size estimates.
     577             :      */
     578      331920 :     check_index_predicates(root, rel);
     579             : 
     580             :     /* Mark rel with estimated output rows, width, etc */
     581      331920 :     set_baserel_size_estimates(root, rel);
     582      331896 : }
     583             : 
     584             : /*
     585             :  * If this relation could possibly be scanned from within a worker, then set
     586             :  * its consider_parallel flag.
     587             :  */
     588             : static void
     589      322800 : set_rel_consider_parallel(PlannerInfo *root, RelOptInfo *rel,
     590             :                           RangeTblEntry *rte)
     591             : {
     592             :     /*
     593             :      * The flag has previously been initialized to false, so we can just
     594             :      * return if it becomes clear that we can't safely set it.
     595             :      */
     596             :     Assert(!rel->consider_parallel);
     597             : 
     598             :     /* Don't call this if parallelism is disallowed for the entire query. */
     599             :     Assert(root->glob->parallelModeOK);
     600             : 
     601             :     /* This should only be called for baserels and appendrel children. */
     602             :     Assert(IS_SIMPLE_REL(rel));
     603             : 
     604             :     /* Assorted checks based on rtekind. */
     605      322800 :     switch (rte->rtekind)
     606             :     {
     607      288436 :         case RTE_RELATION:
     608             : 
     609             :             /*
     610             :              * Currently, parallel workers can't access the leader's temporary
     611             :              * tables.  We could possibly relax this if we wrote all of its
     612             :              * local buffers at the start of the query and made no changes
     613             :              * thereafter (maybe we could allow hint bit changes), and if we
     614             :              * taught the workers to read them.  Writing a large number of
     615             :              * temporary buffers could be expensive, though, and we don't have
     616             :              * the rest of the necessary infrastructure right now anyway.  So
     617             :              * for now, bail out if we see a temporary table.
     618             :              */
     619      288436 :             if (get_rel_persistence(rte->relid) == RELPERSISTENCE_TEMP)
     620        7640 :                 return;
     621             : 
     622             :             /*
     623             :              * Table sampling can be pushed down to workers if the sample
     624             :              * function and its arguments are safe.
     625             :              */
     626      280796 :             if (rte->tablesample != NULL)
     627             :             {
     628         324 :                 char        proparallel = func_parallel(rte->tablesample->tsmhandler);
     629             : 
     630         324 :                 if (proparallel != PROPARALLEL_SAFE)
     631          36 :                     return;
     632         288 :                 if (!is_parallel_safe(root, (Node *) rte->tablesample->args))
     633          12 :                     return;
     634             :             }
     635             : 
     636             :             /*
     637             :              * Ask FDWs whether they can support performing a ForeignScan
     638             :              * within a worker.  Most often, the answer will be no.  For
     639             :              * example, if the nature of the FDW is such that it opens a TCP
     640             :              * connection with a remote server, each parallel worker would end
     641             :              * up with a separate connection, and these connections might not
     642             :              * be appropriately coordinated between workers and the leader.
     643             :              */
     644      280748 :             if (rte->relkind == RELKIND_FOREIGN_TABLE)
     645             :             {
     646             :                 Assert(rel->fdwroutine);
     647        1514 :                 if (!rel->fdwroutine->IsForeignScanParallelSafe)
     648        1450 :                     return;
     649          64 :                 if (!rel->fdwroutine->IsForeignScanParallelSafe(root, rel, rte))
     650           0 :                     return;
     651             :             }
     652             : 
     653             :             /*
     654             :              * There are additional considerations for appendrels, which we'll
     655             :              * deal with in set_append_rel_size and set_append_rel_pathlist.
     656             :              * For now, just set consider_parallel based on the rel's own
     657             :              * quals and targetlist.
     658             :              */
     659      279298 :             break;
     660             : 
     661        6124 :         case RTE_SUBQUERY:
     662             : 
     663             :             /*
     664             :              * There's no intrinsic problem with scanning a subquery-in-FROM
     665             :              * (as distinct from a SubPlan or InitPlan) in a parallel worker.
     666             :              * If the subquery doesn't happen to have any parallel-safe paths,
     667             :              * then flagging it as consider_parallel won't change anything,
     668             :              * but that's true for plain tables, too.  We must set
     669             :              * consider_parallel based on the rel's own quals and targetlist,
     670             :              * so that if a subquery path is parallel-safe but the quals and
     671             :              * projection we're sticking onto it are not, we correctly mark
     672             :              * the SubqueryScanPath as not parallel-safe.  (Note that
     673             :              * set_subquery_pathlist() might push some of these quals down
     674             :              * into the subquery itself, but that doesn't change anything.)
     675             :              *
     676             :              * We can't push sub-select containing LIMIT/OFFSET to workers as
     677             :              * there is no guarantee that the row order will be fully
     678             :              * deterministic, and applying LIMIT/OFFSET will lead to
     679             :              * inconsistent results at the top-level.  (In some cases, where
     680             :              * the result is ordered, we could relax this restriction.  But it
     681             :              * doesn't currently seem worth expending extra effort to do so.)
     682             :              */
     683             :             {
     684        6124 :                 Query      *subquery = castNode(Query, rte->subquery);
     685             : 
     686        6124 :                 if (limit_needed(subquery))
     687         422 :                     return;
     688             :             }
     689        5702 :             break;
     690             : 
     691           0 :         case RTE_JOIN:
     692             :             /* Shouldn't happen; we're only considering baserels here. */
     693             :             Assert(false);
     694           0 :             return;
     695             : 
     696       20110 :         case RTE_FUNCTION:
     697             :             /* Check for parallel-restricted functions. */
     698       20110 :             if (!is_parallel_safe(root, (Node *) rte->functions))
     699        9888 :                 return;
     700       10222 :             break;
     701             : 
     702         548 :         case RTE_TABLEFUNC:
     703             :             /* not parallel safe */
     704         548 :             return;
     705             : 
     706        2760 :         case RTE_VALUES:
     707             :             /* Check for parallel-restricted functions. */
     708        2760 :             if (!is_parallel_safe(root, (Node *) rte->values_lists))
     709           6 :                 return;
     710        2754 :             break;
     711             : 
     712        3262 :         case RTE_CTE:
     713             : 
     714             :             /*
     715             :              * CTE tuplestores aren't shared among parallel workers, so we
     716             :              * force all CTE scans to happen in the leader.  Also, populating
     717             :              * the CTE would require executing a subplan that's not available
     718             :              * in the worker, might be parallel-restricted, and must get
     719             :              * executed only once.
     720             :              */
     721        3262 :             return;
     722             : 
     723         414 :         case RTE_NAMEDTUPLESTORE:
     724             : 
     725             :             /*
     726             :              * tuplestore cannot be shared, at least without more
     727             :              * infrastructure to support that.
     728             :              */
     729         414 :             return;
     730             : 
     731        1146 :         case RTE_RESULT:
     732             :             /* RESULT RTEs, in themselves, are no problem. */
     733        1146 :             break;
     734             :     }
     735             : 
     736             :     /*
     737             :      * If there's anything in baserestrictinfo that's parallel-restricted, we
     738             :      * give up on parallelizing access to this relation.  We could consider
     739             :      * instead postponing application of the restricted quals until we're
     740             :      * above all the parallelism in the plan tree, but it's not clear that
     741             :      * that would be a win in very many cases, and it might be tricky to make
     742             :      * outer join clauses work correctly.  It would likely break equivalence
     743             :      * classes, too.
     744             :      */
     745      299122 :     if (!is_parallel_safe(root, (Node *) rel->baserestrictinfo))
     746       20142 :         return;
     747             : 
     748             :     /*
     749             :      * Likewise, if the relation's outputs are not parallel-safe, give up.
     750             :      * (Usually, they're just Vars, but sometimes they're not.)
     751             :      */
     752      278980 :     if (!is_parallel_safe(root, (Node *) rel->reltarget->exprs))
     753          18 :         return;
     754             : 
     755             :     /* We have a winner. */
     756      278962 :     rel->consider_parallel = true;
     757             : }
     758             : 
     759             : /*
     760             :  * set_plain_rel_pathlist
     761             :  *    Build access paths for a plain relation (no subquery, no inheritance)
     762             :  */
     763             : static void
     764      331896 : set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
     765             : {
     766             :     Relids      required_outer;
     767             : 
     768             :     /*
     769             :      * We don't support pushing join clauses into the quals of a seqscan, but
     770             :      * it could still have required parameterization due to LATERAL refs in
     771             :      * its tlist.
     772             :      */
     773      331896 :     required_outer = rel->lateral_relids;
     774             : 
     775             :     /* Consider sequential scan */
     776      331896 :     add_path(rel, create_seqscan_path(root, rel, required_outer, 0));
     777             : 
     778             :     /* If appropriate, consider parallel sequential scan */
     779      331896 :     if (rel->consider_parallel && required_outer == NULL)
     780      246134 :         create_plain_partial_paths(root, rel);
     781             : 
     782             :     /* Consider index scans */
     783      331896 :     create_index_paths(root, rel);
     784             : 
     785             :     /* Consider TID scans */
     786      331896 :     create_tidscan_paths(root, rel);
     787      331896 : }
     788             : 
     789             : /*
     790             :  * create_plain_partial_paths
     791             :  *    Build partial access paths for parallel scan of a plain relation
     792             :  */
     793             : static void
     794      246134 : create_plain_partial_paths(PlannerInfo *root, RelOptInfo *rel)
     795             : {
     796             :     int         parallel_workers;
     797             : 
     798      246134 :     parallel_workers = compute_parallel_worker(rel, rel->pages, -1,
     799             :                                                max_parallel_workers_per_gather);
     800             : 
     801             :     /* If any limit was set to zero, the user doesn't want a parallel scan. */
     802      246134 :     if (parallel_workers <= 0)
     803      219970 :         return;
     804             : 
     805             :     /* Add an unordered partial path based on a parallel sequential scan. */
     806       26164 :     add_partial_path(rel, create_seqscan_path(root, rel, NULL, parallel_workers));
     807             : }
     808             : 
     809             : /*
     810             :  * set_tablesample_rel_size
     811             :  *    Set size estimates for a sampled relation
     812             :  */
     813             : static void
     814         300 : set_tablesample_rel_size(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
     815             : {
     816         300 :     TableSampleClause *tsc = rte->tablesample;
     817             :     TsmRoutine *tsm;
     818             :     BlockNumber pages;
     819             :     double      tuples;
     820             : 
     821             :     /*
     822             :      * Test any partial indexes of rel for applicability.  We must do this
     823             :      * first since partial unique indexes can affect size estimates.
     824             :      */
     825         300 :     check_index_predicates(root, rel);
     826             : 
     827             :     /*
     828             :      * Call the sampling method's estimation function to estimate the number
     829             :      * of pages it will read and the number of tuples it will return.  (Note:
     830             :      * we assume the function returns sane values.)
     831             :      */
     832         300 :     tsm = GetTsmRoutine(tsc->tsmhandler);
     833         300 :     tsm->SampleScanGetSampleSize(root, rel, tsc->args,
     834             :                                  &pages, &tuples);
     835             : 
     836             :     /*
     837             :      * For the moment, because we will only consider a SampleScan path for the
     838             :      * rel, it's okay to just overwrite the pages and tuples estimates for the
     839             :      * whole relation.  If we ever consider multiple path types for sampled
     840             :      * rels, we'll need more complication.
     841             :      */
     842         300 :     rel->pages = pages;
     843         300 :     rel->tuples = tuples;
     844             : 
     845             :     /* Mark rel with estimated output rows, width, etc */
     846         300 :     set_baserel_size_estimates(root, rel);
     847         300 : }
     848             : 
     849             : /*
     850             :  * set_tablesample_rel_pathlist
     851             :  *    Build access paths for a sampled relation
     852             :  */
     853             : static void
     854         300 : set_tablesample_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
     855             : {
     856             :     Relids      required_outer;
     857             :     Path       *path;
     858             : 
     859             :     /*
     860             :      * We don't support pushing join clauses into the quals of a samplescan,
     861             :      * but it could still have required parameterization due to LATERAL refs
     862             :      * in its tlist or TABLESAMPLE arguments.
     863             :      */
     864         300 :     required_outer = rel->lateral_relids;
     865             : 
     866             :     /* Consider sampled scan */
     867         300 :     path = create_samplescan_path(root, rel, required_outer);
     868             : 
     869             :     /*
     870             :      * If the sampling method does not support repeatable scans, we must avoid
     871             :      * plans that would scan the rel multiple times.  Ideally, we'd simply
     872             :      * avoid putting the rel on the inside of a nestloop join; but adding such
     873             :      * a consideration to the planner seems like a great deal of complication
     874             :      * to support an uncommon usage of second-rate sampling methods.  Instead,
     875             :      * if there is a risk that the query might perform an unsafe join, just
     876             :      * wrap the SampleScan in a Materialize node.  We can check for joins by
     877             :      * counting the membership of all_query_rels (note that this correctly
     878             :      * counts inheritance trees as single rels).  If we're inside a subquery,
     879             :      * we can't easily check whether a join might occur in the outer query, so
     880             :      * just assume one is possible.
     881             :      *
     882             :      * GetTsmRoutine is relatively expensive compared to the other tests here,
     883             :      * so check repeatable_across_scans last, even though that's a bit odd.
     884             :      */
     885         574 :     if ((root->query_level > 1 ||
     886         274 :          bms_membership(root->all_query_rels) != BMS_SINGLETON) &&
     887          92 :         !(GetTsmRoutine(rte->tablesample->tsmhandler)->repeatable_across_scans))
     888             :     {
     889           8 :         path = (Path *) create_material_path(rel, path);
     890             :     }
     891             : 
     892         300 :     add_path(rel, path);
     893             : 
     894             :     /* For the moment, at least, there are no other paths to consider */
     895         300 : }
     896             : 
     897             : /*
     898             :  * set_foreign_size
     899             :  *      Set size estimates for a foreign table RTE
     900             :  */
     901             : static void
     902        2348 : set_foreign_size(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
     903             : {
     904             :     /* Mark rel with estimated output rows, width, etc */
     905        2348 :     set_foreign_size_estimates(root, rel);
     906             : 
     907             :     /* Let FDW adjust the size estimates, if it can */
     908        2348 :     rel->fdwroutine->GetForeignRelSize(root, rel, rte->relid);
     909             : 
     910             :     /* ... but do not let it set the rows estimate to zero */
     911        2344 :     rel->rows = clamp_row_est(rel->rows);
     912             : 
     913             :     /*
     914             :      * Also, make sure rel->tuples is not insane relative to rel->rows.
     915             :      * Notably, this ensures sanity if pg_class.reltuples contains -1 and the
     916             :      * FDW doesn't do anything to replace that.
     917             :      */
     918        2344 :     rel->tuples = Max(rel->tuples, rel->rows);
     919        2344 : }
     920             : 
     921             : /*
     922             :  * set_foreign_pathlist
     923             :  *      Build access paths for a foreign table RTE
     924             :  */
     925             : static void
     926        2344 : set_foreign_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
     927             : {
     928             :     /* Call the FDW's GetForeignPaths function to generate path(s) */
     929        2344 :     rel->fdwroutine->GetForeignPaths(root, rel, rte->relid);
     930        2344 : }
     931             : 
     932             : /*
     933             :  * set_append_rel_size
     934             :  *    Set size estimates for a simple "append relation"
     935             :  *
     936             :  * The passed-in rel and RTE represent the entire append relation.  The
     937             :  * relation's contents are computed by appending together the output of the
     938             :  * individual member relations.  Note that in the non-partitioned inheritance
     939             :  * case, the first member relation is actually the same table as is mentioned
     940             :  * in the parent RTE ... but it has a different RTE and RelOptInfo.  This is
     941             :  * a good thing because their outputs are not the same size.
     942             :  */
     943             : static void
     944       20062 : set_append_rel_size(PlannerInfo *root, RelOptInfo *rel,
     945             :                     Index rti, RangeTblEntry *rte)
     946             : {
     947       20062 :     int         parentRTindex = rti;
     948             :     bool        has_live_children;
     949             :     double      parent_rows;
     950             :     double      parent_size;
     951             :     double     *parent_attrsizes;
     952             :     int         nattrs;
     953             :     ListCell   *l;
     954             : 
     955             :     /* Guard against stack overflow due to overly deep inheritance tree. */
     956       20062 :     check_stack_depth();
     957             : 
     958             :     Assert(IS_SIMPLE_REL(rel));
     959             : 
     960             :     /*
     961             :      * If this is a partitioned baserel, set the consider_partitionwise_join
     962             :      * flag; currently, we only consider partitionwise joins with the baserel
     963             :      * if its targetlist doesn't contain a whole-row Var.
     964             :      */
     965       20062 :     if (enable_partitionwise_join &&
     966        4070 :         rel->reloptkind == RELOPT_BASEREL &&
     967        3386 :         rte->relkind == RELKIND_PARTITIONED_TABLE &&
     968        3386 :         bms_is_empty(rel->attr_needed[InvalidAttrNumber - rel->min_attr]))
     969        3310 :         rel->consider_partitionwise_join = true;
     970             : 
     971             :     /*
     972             :      * Initialize to compute size estimates for whole append relation.
     973             :      *
     974             :      * We handle width estimates by weighting the widths of different child
     975             :      * rels proportionally to their number of rows.  This is sensible because
     976             :      * the use of width estimates is mainly to compute the total relation
     977             :      * "footprint" if we have to sort or hash it.  To do this, we sum the
     978             :      * total equivalent size (in "double" arithmetic) and then divide by the
     979             :      * total rowcount estimate.  This is done separately for the total rel
     980             :      * width and each attribute.
     981             :      *
     982             :      * Note: if you consider changing this logic, beware that child rels could
     983             :      * have zero rows and/or width, if they were excluded by constraints.
     984             :      */
     985       20062 :     has_live_children = false;
     986       20062 :     parent_rows = 0;
     987       20062 :     parent_size = 0;
     988       20062 :     nattrs = rel->max_attr - rel->min_attr + 1;
     989       20062 :     parent_attrsizes = (double *) palloc0(nattrs * sizeof(double));
     990             : 
     991      104362 :     foreach(l, root->append_rel_list)
     992             :     {
     993       84302 :         AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l);
     994             :         int         childRTindex;
     995             :         RangeTblEntry *childRTE;
     996             :         RelOptInfo *childrel;
     997             :         List       *childrinfos;
     998             :         ListCell   *parentvars;
     999             :         ListCell   *childvars;
    1000             :         ListCell   *lc;
    1001             : 
    1002             :         /* append_rel_list contains all append rels; ignore others */
    1003       84302 :         if (appinfo->parent_relid != parentRTindex)
    1004       42170 :             continue;
    1005             : 
    1006       42384 :         childRTindex = appinfo->child_relid;
    1007       42384 :         childRTE = root->simple_rte_array[childRTindex];
    1008             : 
    1009             :         /*
    1010             :          * The child rel's RelOptInfo was already created during
    1011             :          * add_other_rels_to_query.
    1012             :          */
    1013       42384 :         childrel = find_base_rel(root, childRTindex);
    1014             :         Assert(childrel->reloptkind == RELOPT_OTHER_MEMBER_REL);
    1015             : 
    1016             :         /* We may have already proven the child to be dummy. */
    1017       42384 :         if (IS_DUMMY_REL(childrel))
    1018          18 :             continue;
    1019             : 
    1020             :         /*
    1021             :          * We have to copy the parent's targetlist and quals to the child,
    1022             :          * with appropriate substitution of variables.  However, the
    1023             :          * baserestrictinfo quals were already copied/substituted when the
    1024             :          * child RelOptInfo was built.  So we don't need any additional setup
    1025             :          * before applying constraint exclusion.
    1026             :          */
    1027       42366 :         if (relation_excluded_by_constraints(root, childrel, childRTE))
    1028             :         {
    1029             :             /*
    1030             :              * This child need not be scanned, so we can omit it from the
    1031             :              * appendrel.
    1032             :              */
    1033          96 :             set_dummy_rel_pathlist(childrel);
    1034          96 :             continue;
    1035             :         }
    1036             : 
    1037             :         /*
    1038             :          * Constraint exclusion failed, so copy the parent's join quals and
    1039             :          * targetlist to the child, with appropriate variable substitutions.
    1040             :          *
    1041             :          * We skip join quals that came from above outer joins that can null
    1042             :          * this rel, since they would be of no value while generating paths
    1043             :          * for the child.  This saves some effort while processing the child
    1044             :          * rel, and it also avoids an implementation restriction in
    1045             :          * adjust_appendrel_attrs (it can't apply nullingrels to a non-Var).
    1046             :          */
    1047       42270 :         childrinfos = NIL;
    1048       54906 :         foreach(lc, rel->joininfo)
    1049             :         {
    1050       12636 :             RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
    1051             : 
    1052       12636 :             if (!bms_overlap(rinfo->clause_relids, rel->nulling_relids))
    1053       10314 :                 childrinfos = lappend(childrinfos,
    1054       10314 :                                       adjust_appendrel_attrs(root,
    1055             :                                                              (Node *) rinfo,
    1056             :                                                              1, &appinfo));
    1057             :         }
    1058       42270 :         childrel->joininfo = childrinfos;
    1059             : 
    1060             :         /*
    1061             :          * Now for the child's targetlist.
    1062             :          *
    1063             :          * NB: the resulting childrel->reltarget->exprs may contain arbitrary
    1064             :          * expressions, which otherwise would not occur in a rel's targetlist.
    1065             :          * Code that might be looking at an appendrel child must cope with
    1066             :          * such.  (Normally, a rel's targetlist would only include Vars and
    1067             :          * PlaceHolderVars.)  XXX we do not bother to update the cost or width
    1068             :          * fields of childrel->reltarget; not clear if that would be useful.
    1069             :          */
    1070       84540 :         childrel->reltarget->exprs = (List *)
    1071       42270 :             adjust_appendrel_attrs(root,
    1072       42270 :                                    (Node *) rel->reltarget->exprs,
    1073             :                                    1, &appinfo);
    1074             : 
    1075             :         /*
    1076             :          * We have to make child entries in the EquivalenceClass data
    1077             :          * structures as well.  This is needed either if the parent
    1078             :          * participates in some eclass joins (because we will want to consider
    1079             :          * inner-indexscan joins on the individual children) or if the parent
    1080             :          * has useful pathkeys (because we should try to build MergeAppend
    1081             :          * paths that produce those sort orderings).
    1082             :          */
    1083       42270 :         if (rel->has_eclass_joins || has_useful_pathkeys(root, rel))
    1084       21470 :             add_child_rel_equivalences(root, appinfo, rel, childrel);
    1085       42270 :         childrel->has_eclass_joins = rel->has_eclass_joins;
    1086             : 
    1087             :         /*
    1088             :          * Note: we could compute appropriate attr_needed data for the child's
    1089             :          * variables, by transforming the parent's attr_needed through the
    1090             :          * translated_vars mapping.  However, currently there's no need
    1091             :          * because attr_needed is only examined for base relations not
    1092             :          * otherrels.  So we just leave the child's attr_needed empty.
    1093             :          */
    1094             : 
    1095             :         /*
    1096             :          * If we consider partitionwise joins with the parent rel, do the same
    1097             :          * for partitioned child rels.
    1098             :          *
    1099             :          * Note: here we abuse the consider_partitionwise_join flag by setting
    1100             :          * it for child rels that are not themselves partitioned.  We do so to
    1101             :          * tell try_partitionwise_join() that the child rel is sufficiently
    1102             :          * valid to be used as a per-partition input, even if it later gets
    1103             :          * proven to be dummy.  (It's not usable until we've set up the
    1104             :          * reltarget and EC entries, which we just did.)
    1105             :          */
    1106       42270 :         if (rel->consider_partitionwise_join)
    1107       10904 :             childrel->consider_partitionwise_join = true;
    1108             : 
    1109             :         /*
    1110             :          * If parallelism is allowable for this query in general, see whether
    1111             :          * it's allowable for this childrel in particular.  But if we've
    1112             :          * already decided the appendrel is not parallel-safe as a whole,
    1113             :          * there's no point in considering parallelism for this child.  For
    1114             :          * consistency, do this before calling set_rel_size() for the child.
    1115             :          */
    1116       42270 :         if (root->glob->parallelModeOK && rel->consider_parallel)
    1117       30440 :             set_rel_consider_parallel(root, childrel, childRTE);
    1118             : 
    1119             :         /*
    1120             :          * Compute the child's size.
    1121             :          */
    1122       42270 :         set_rel_size(root, childrel, childRTindex, childRTE);
    1123             : 
    1124             :         /*
    1125             :          * It is possible that constraint exclusion detected a contradiction
    1126             :          * within a child subquery, even though we didn't prove one above. If
    1127             :          * so, we can skip this child.
    1128             :          */
    1129       42268 :         if (IS_DUMMY_REL(childrel))
    1130         138 :             continue;
    1131             : 
    1132             :         /* We have at least one live child. */
    1133       42130 :         has_live_children = true;
    1134             : 
    1135             :         /*
    1136             :          * If any live child is not parallel-safe, treat the whole appendrel
    1137             :          * as not parallel-safe.  In future we might be able to generate plans
    1138             :          * in which some children are farmed out to workers while others are
    1139             :          * not; but we don't have that today, so it's a waste to consider
    1140             :          * partial paths anywhere in the appendrel unless it's all safe.
    1141             :          * (Child rels visited before this one will be unmarked in
    1142             :          * set_append_rel_pathlist().)
    1143             :          */
    1144       42130 :         if (!childrel->consider_parallel)
    1145       12316 :             rel->consider_parallel = false;
    1146             : 
    1147             :         /*
    1148             :          * Accumulate size information from each live child.
    1149             :          */
    1150             :         Assert(childrel->rows > 0);
    1151             : 
    1152       42130 :         parent_rows += childrel->rows;
    1153       42130 :         parent_size += childrel->reltarget->width * childrel->rows;
    1154             : 
    1155             :         /*
    1156             :          * Accumulate per-column estimates too.  We need not do anything for
    1157             :          * PlaceHolderVars in the parent list.  If child expression isn't a
    1158             :          * Var, or we didn't record a width estimate for it, we have to fall
    1159             :          * back on a datatype-based estimate.
    1160             :          *
    1161             :          * By construction, child's targetlist is 1-to-1 with parent's.
    1162             :          */
    1163      134170 :         forboth(parentvars, rel->reltarget->exprs,
    1164             :                 childvars, childrel->reltarget->exprs)
    1165             :         {
    1166       92040 :             Var        *parentvar = (Var *) lfirst(parentvars);
    1167       92040 :             Node       *childvar = (Node *) lfirst(childvars);
    1168             : 
    1169       92040 :             if (IsA(parentvar, Var) && parentvar->varno == parentRTindex)
    1170             :             {
    1171       80420 :                 int         pndx = parentvar->varattno - rel->min_attr;
    1172       80420 :                 int32       child_width = 0;
    1173             : 
    1174       80420 :                 if (IsA(childvar, Var) &&
    1175       78398 :                     ((Var *) childvar)->varno == childrel->relid)
    1176             :                 {
    1177       78332 :                     int         cndx = ((Var *) childvar)->varattno - childrel->min_attr;
    1178             : 
    1179       78332 :                     child_width = childrel->attr_widths[cndx];
    1180             :                 }
    1181       80420 :                 if (child_width <= 0)
    1182        2088 :                     child_width = get_typavgwidth(exprType(childvar),
    1183             :                                                   exprTypmod(childvar));
    1184             :                 Assert(child_width > 0);
    1185       80420 :                 parent_attrsizes[pndx] += child_width * childrel->rows;
    1186             :             }
    1187             :         }
    1188             :     }
    1189             : 
    1190       20060 :     if (has_live_children)
    1191             :     {
    1192             :         /*
    1193             :          * Save the finished size estimates.
    1194             :          */
    1195             :         int         i;
    1196             : 
    1197             :         Assert(parent_rows > 0);
    1198       19766 :         rel->rows = parent_rows;
    1199       19766 :         rel->reltarget->width = rint(parent_size / parent_rows);
    1200      201426 :         for (i = 0; i < nattrs; i++)
    1201      181660 :             rel->attr_widths[i] = rint(parent_attrsizes[i] / parent_rows);
    1202             : 
    1203             :         /*
    1204             :          * Set "raw tuples" count equal to "rows" for the appendrel; needed
    1205             :          * because some places assume rel->tuples is valid for any baserel.
    1206             :          */
    1207       19766 :         rel->tuples = parent_rows;
    1208             : 
    1209             :         /*
    1210             :          * Note that we leave rel->pages as zero; this is important to avoid
    1211             :          * double-counting the appendrel tree in total_table_pages.
    1212             :          */
    1213             :     }
    1214             :     else
    1215             :     {
    1216             :         /*
    1217             :          * All children were excluded by constraints, so mark the whole
    1218             :          * appendrel dummy.  We must do this in this phase so that the rel's
    1219             :          * dummy-ness is visible when we generate paths for other rels.
    1220             :          */
    1221         294 :         set_dummy_rel_pathlist(rel);
    1222             :     }
    1223             : 
    1224       20060 :     pfree(parent_attrsizes);
    1225       20060 : }
    1226             : 
    1227             : /*
    1228             :  * set_append_rel_pathlist
    1229             :  *    Build access paths for an "append relation"
    1230             :  */
    1231             : static void
    1232       19766 : set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
    1233             :                         Index rti, RangeTblEntry *rte)
    1234             : {
    1235       19766 :     int         parentRTindex = rti;
    1236       19766 :     List       *live_childrels = NIL;
    1237             :     ListCell   *l;
    1238             : 
    1239             :     /*
    1240             :      * Generate access paths for each member relation, and remember the
    1241             :      * non-dummy children.
    1242             :      */
    1243      103652 :     foreach(l, root->append_rel_list)
    1244             :     {
    1245       83886 :         AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l);
    1246             :         int         childRTindex;
    1247             :         RangeTblEntry *childRTE;
    1248             :         RelOptInfo *childrel;
    1249             : 
    1250             :         /* append_rel_list contains all append rels; ignore others */
    1251       83886 :         if (appinfo->parent_relid != parentRTindex)
    1252       41570 :             continue;
    1253             : 
    1254             :         /* Re-locate the child RTE and RelOptInfo */
    1255       42316 :         childRTindex = appinfo->child_relid;
    1256       42316 :         childRTE = root->simple_rte_array[childRTindex];
    1257       42316 :         childrel = root->simple_rel_array[childRTindex];
    1258             : 
    1259             :         /*
    1260             :          * If set_append_rel_size() decided the parent appendrel was
    1261             :          * parallel-unsafe at some point after visiting this child rel, we
    1262             :          * need to propagate the unsafety marking down to the child, so that
    1263             :          * we don't generate useless partial paths for it.
    1264             :          */
    1265       42316 :         if (!rel->consider_parallel)
    1266       12422 :             childrel->consider_parallel = false;
    1267             : 
    1268             :         /*
    1269             :          * Compute the child's access paths.
    1270             :          */
    1271       42316 :         set_rel_pathlist(root, childrel, childRTindex, childRTE);
    1272             : 
    1273             :         /*
    1274             :          * If child is dummy, ignore it.
    1275             :          */
    1276       42316 :         if (IS_DUMMY_REL(childrel))
    1277         186 :             continue;
    1278             : 
    1279             :         /*
    1280             :          * Child is live, so add it to the live_childrels list for use below.
    1281             :          */
    1282       42130 :         live_childrels = lappend(live_childrels, childrel);
    1283             :     }
    1284             : 
    1285             :     /* Add paths to the append relation. */
    1286       19766 :     add_paths_to_append_rel(root, rel, live_childrels);
    1287       19766 : }
    1288             : 
    1289             : 
    1290             : /*
    1291             :  * add_paths_to_append_rel
    1292             :  *      Generate paths for the given append relation given the set of non-dummy
    1293             :  *      child rels.
    1294             :  *
    1295             :  * The function collects all parameterizations and orderings supported by the
    1296             :  * non-dummy children. For every such parameterization or ordering, it creates
    1297             :  * an append path collecting one path from each non-dummy child with given
    1298             :  * parameterization or ordering. Similarly it collects partial paths from
    1299             :  * non-dummy children to create partial append paths.
    1300             :  */
    1301             : void
    1302       34166 : add_paths_to_append_rel(PlannerInfo *root, RelOptInfo *rel,
    1303             :                         List *live_childrels)
    1304             : {
    1305       34166 :     List       *subpaths = NIL;
    1306       34166 :     bool        subpaths_valid = true;
    1307       34166 :     List       *startup_subpaths = NIL;
    1308       34166 :     bool        startup_subpaths_valid = true;
    1309       34166 :     List       *partial_subpaths = NIL;
    1310       34166 :     List       *pa_partial_subpaths = NIL;
    1311       34166 :     List       *pa_nonpartial_subpaths = NIL;
    1312       34166 :     bool        partial_subpaths_valid = true;
    1313             :     bool        pa_subpaths_valid;
    1314       34166 :     List       *all_child_pathkeys = NIL;
    1315       34166 :     List       *all_child_outers = NIL;
    1316             :     ListCell   *l;
    1317       34166 :     double      partial_rows = -1;
    1318             : 
    1319             :     /* If appropriate, consider parallel append */
    1320       34166 :     pa_subpaths_valid = enable_parallel_append && rel->consider_parallel;
    1321             : 
    1322             :     /*
    1323             :      * For every non-dummy child, remember the cheapest path.  Also, identify
    1324             :      * all pathkeys (orderings) and parameterizations (required_outer sets)
    1325             :      * available for the non-dummy member relations.
    1326             :      */
    1327      104830 :     foreach(l, live_childrels)
    1328             :     {
    1329       70664 :         RelOptInfo *childrel = lfirst(l);
    1330             :         ListCell   *lcp;
    1331       70664 :         Path       *cheapest_partial_path = NULL;
    1332             : 
    1333             :         /*
    1334             :          * If child has an unparameterized cheapest-total path, add that to
    1335             :          * the unparameterized Append path we are constructing for the parent.
    1336             :          * If not, there's no workable unparameterized path.
    1337             :          *
    1338             :          * With partitionwise aggregates, the child rel's pathlist may be
    1339             :          * empty, so don't assume that a path exists here.
    1340             :          */
    1341       70664 :         if (childrel->pathlist != NIL &&
    1342       70664 :             childrel->cheapest_total_path->param_info == NULL)
    1343       69932 :             accumulate_append_subpath(childrel->cheapest_total_path,
    1344             :                                       &subpaths, NULL);
    1345             :         else
    1346         732 :             subpaths_valid = false;
    1347             : 
    1348             :         /*
    1349             :          * When the planner is considering cheap startup plans, we'll also
    1350             :          * collect all the cheapest_startup_paths (if set) and build an
    1351             :          * AppendPath containing those as subpaths.
    1352             :          */
    1353       70664 :         if (rel->consider_startup && childrel->cheapest_startup_path != NULL)
    1354             :         {
    1355             :             /* cheapest_startup_path must not be a parameterized path. */
    1356             :             Assert(childrel->cheapest_startup_path->param_info == NULL);
    1357        1286 :             accumulate_append_subpath(childrel->cheapest_startup_path,
    1358             :                                       &startup_subpaths,
    1359             :                                       NULL);
    1360             :         }
    1361             :         else
    1362       69378 :             startup_subpaths_valid = false;
    1363             : 
    1364             : 
    1365             :         /* Same idea, but for a partial plan. */
    1366       70664 :         if (childrel->partial_pathlist != NIL)
    1367             :         {
    1368       47616 :             cheapest_partial_path = linitial(childrel->partial_pathlist);
    1369       47616 :             accumulate_append_subpath(cheapest_partial_path,
    1370             :                                       &partial_subpaths, NULL);
    1371             :         }
    1372             :         else
    1373       23048 :             partial_subpaths_valid = false;
    1374             : 
    1375             :         /*
    1376             :          * Same idea, but for a parallel append mixing partial and non-partial
    1377             :          * paths.
    1378             :          */
    1379       70664 :         if (pa_subpaths_valid)
    1380             :         {
    1381       50200 :             Path       *nppath = NULL;
    1382             : 
    1383             :             nppath =
    1384       50200 :                 get_cheapest_parallel_safe_total_inner(childrel->pathlist);
    1385             : 
    1386       50200 :             if (cheapest_partial_path == NULL && nppath == NULL)
    1387             :             {
    1388             :                 /* Neither a partial nor a parallel-safe path?  Forget it. */
    1389         450 :                 pa_subpaths_valid = false;
    1390             :             }
    1391       49750 :             else if (nppath == NULL ||
    1392       47166 :                      (cheapest_partial_path != NULL &&
    1393       47166 :                       cheapest_partial_path->total_cost < nppath->total_cost))
    1394             :             {
    1395             :                 /* Partial path is cheaper or the only option. */
    1396             :                 Assert(cheapest_partial_path != NULL);
    1397       46930 :                 accumulate_append_subpath(cheapest_partial_path,
    1398             :                                           &pa_partial_subpaths,
    1399             :                                           &pa_nonpartial_subpaths);
    1400             :             }
    1401             :             else
    1402             :             {
    1403             :                 /*
    1404             :                  * Either we've got only a non-partial path, or we think that
    1405             :                  * a single backend can execute the best non-partial path
    1406             :                  * faster than all the parallel backends working together can
    1407             :                  * execute the best partial path.
    1408             :                  *
    1409             :                  * It might make sense to be more aggressive here.  Even if
    1410             :                  * the best non-partial path is more expensive than the best
    1411             :                  * partial path, it could still be better to choose the
    1412             :                  * non-partial path if there are several such paths that can
    1413             :                  * be given to different workers.  For now, we don't try to
    1414             :                  * figure that out.
    1415             :                  */
    1416        2820 :                 accumulate_append_subpath(nppath,
    1417             :                                           &pa_nonpartial_subpaths,
    1418             :                                           NULL);
    1419             :             }
    1420             :         }
    1421             : 
    1422             :         /*
    1423             :          * Collect lists of all the available path orderings and
    1424             :          * parameterizations for all the children.  We use these as a
    1425             :          * heuristic to indicate which sort orderings and parameterizations we
    1426             :          * should build Append and MergeAppend paths for.
    1427             :          */
    1428      161240 :         foreach(lcp, childrel->pathlist)
    1429             :         {
    1430       90576 :             Path       *childpath = (Path *) lfirst(lcp);
    1431       90576 :             List       *childkeys = childpath->pathkeys;
    1432       90576 :             Relids      childouter = PATH_REQ_OUTER(childpath);
    1433             : 
    1434             :             /* Unsorted paths don't contribute to pathkey list */
    1435       90576 :             if (childkeys != NIL)
    1436             :             {
    1437             :                 ListCell   *lpk;
    1438       20110 :                 bool        found = false;
    1439             : 
    1440             :                 /* Have we already seen this ordering? */
    1441       20298 :                 foreach(lpk, all_child_pathkeys)
    1442             :                 {
    1443       14530 :                     List       *existing_pathkeys = (List *) lfirst(lpk);
    1444             : 
    1445       14530 :                     if (compare_pathkeys(existing_pathkeys,
    1446             :                                          childkeys) == PATHKEYS_EQUAL)
    1447             :                     {
    1448       14342 :                         found = true;
    1449       14342 :                         break;
    1450             :                     }
    1451             :                 }
    1452       20110 :                 if (!found)
    1453             :                 {
    1454             :                     /* No, so add it to all_child_pathkeys */
    1455        5768 :                     all_child_pathkeys = lappend(all_child_pathkeys,
    1456             :                                                  childkeys);
    1457             :                 }
    1458             :             }
    1459             : 
    1460             :             /* Unparameterized paths don't contribute to param-set list */
    1461       90576 :             if (childouter)
    1462             :             {
    1463             :                 ListCell   *lco;
    1464        5880 :                 bool        found = false;
    1465             : 
    1466             :                 /* Have we already seen this param set? */
    1467        6492 :                 foreach(lco, all_child_outers)
    1468             :                 {
    1469        4266 :                     Relids      existing_outers = (Relids) lfirst(lco);
    1470             : 
    1471        4266 :                     if (bms_equal(existing_outers, childouter))
    1472             :                     {
    1473        3654 :                         found = true;
    1474        3654 :                         break;
    1475             :                     }
    1476             :                 }
    1477        5880 :                 if (!found)
    1478             :                 {
    1479             :                     /* No, so add it to all_child_outers */
    1480        2226 :                     all_child_outers = lappend(all_child_outers,
    1481             :                                                childouter);
    1482             :                 }
    1483             :             }
    1484             :         }
    1485             :     }
    1486             : 
    1487             :     /*
    1488             :      * If we found unparameterized paths for all children, build an unordered,
    1489             :      * unparameterized Append path for the rel.  (Note: this is correct even
    1490             :      * if we have zero or one live subpath due to constraint exclusion.)
    1491             :      */
    1492       34166 :     if (subpaths_valid)
    1493       33854 :         add_path(rel, (Path *) create_append_path(root, rel, subpaths, NIL,
    1494             :                                                   NIL, NULL, 0, false,
    1495             :                                                   -1));
    1496             : 
    1497             :     /* build an AppendPath for the cheap startup paths, if valid */
    1498       34166 :     if (startup_subpaths_valid)
    1499         544 :         add_path(rel, (Path *) create_append_path(root, rel, startup_subpaths,
    1500             :                                                   NIL, NIL, NULL, 0, false, -1));
    1501             : 
    1502             :     /*
    1503             :      * Consider an append of unordered, unparameterized partial paths.  Make
    1504             :      * it parallel-aware if possible.
    1505             :      */
    1506       34166 :     if (partial_subpaths_valid && partial_subpaths != NIL)
    1507             :     {
    1508             :         AppendPath *appendpath;
    1509             :         ListCell   *lc;
    1510       21408 :         int         parallel_workers = 0;
    1511             : 
    1512             :         /* Find the highest number of workers requested for any subpath. */
    1513       73192 :         foreach(lc, partial_subpaths)
    1514             :         {
    1515       51784 :             Path       *path = lfirst(lc);
    1516             : 
    1517       51784 :             parallel_workers = Max(parallel_workers, path->parallel_workers);
    1518             :         }
    1519             :         Assert(parallel_workers > 0);
    1520             : 
    1521             :         /*
    1522             :          * If the use of parallel append is permitted, always request at least
    1523             :          * log2(# of children) workers.  We assume it can be useful to have
    1524             :          * extra workers in this case because they will be spread out across
    1525             :          * the children.  The precise formula is just a guess, but we don't
    1526             :          * want to end up with a radically different answer for a table with N
    1527             :          * partitions vs. an unpartitioned table with the same data, so the
    1528             :          * use of some kind of log-scaling here seems to make some sense.
    1529             :          */
    1530       21408 :         if (enable_parallel_append)
    1531             :         {
    1532       21360 :             parallel_workers = Max(parallel_workers,
    1533             :                                    pg_leftmost_one_pos32(list_length(live_childrels)) + 1);
    1534       21360 :             parallel_workers = Min(parallel_workers,
    1535             :                                    max_parallel_workers_per_gather);
    1536             :         }
    1537             :         Assert(parallel_workers > 0);
    1538             : 
    1539             :         /* Generate a partial append path. */
    1540       21408 :         appendpath = create_append_path(root, rel, NIL, partial_subpaths,
    1541             :                                         NIL, NULL, parallel_workers,
    1542             :                                         enable_parallel_append,
    1543             :                                         -1);
    1544             : 
    1545             :         /*
    1546             :          * Make sure any subsequent partial paths use the same row count
    1547             :          * estimate.
    1548             :          */
    1549       21408 :         partial_rows = appendpath->path.rows;
    1550             : 
    1551             :         /* Add the path. */
    1552       21408 :         add_partial_path(rel, (Path *) appendpath);
    1553             :     }
    1554             : 
    1555             :     /*
    1556             :      * Consider a parallel-aware append using a mix of partial and non-partial
    1557             :      * paths.  (This only makes sense if there's at least one child which has
    1558             :      * a non-partial path that is substantially cheaper than any partial path;
    1559             :      * otherwise, we should use the append path added in the previous step.)
    1560             :      */
    1561       34166 :     if (pa_subpaths_valid && pa_nonpartial_subpaths != NIL)
    1562             :     {
    1563             :         AppendPath *appendpath;
    1564             :         ListCell   *lc;
    1565        1472 :         int         parallel_workers = 0;
    1566             : 
    1567             :         /*
    1568             :          * Find the highest number of workers requested for any partial
    1569             :          * subpath.
    1570             :          */
    1571        2356 :         foreach(lc, pa_partial_subpaths)
    1572             :         {
    1573         884 :             Path       *path = lfirst(lc);
    1574             : 
    1575         884 :             parallel_workers = Max(parallel_workers, path->parallel_workers);
    1576             :         }
    1577             : 
    1578             :         /*
    1579             :          * Same formula here as above.  It's even more important in this
    1580             :          * instance because the non-partial paths won't contribute anything to
    1581             :          * the planned number of parallel workers.
    1582             :          */
    1583        1472 :         parallel_workers = Max(parallel_workers,
    1584             :                                pg_leftmost_one_pos32(list_length(live_childrels)) + 1);
    1585        1472 :         parallel_workers = Min(parallel_workers,
    1586             :                                max_parallel_workers_per_gather);
    1587             :         Assert(parallel_workers > 0);
    1588             : 
    1589        1472 :         appendpath = create_append_path(root, rel, pa_nonpartial_subpaths,
    1590             :                                         pa_partial_subpaths,
    1591             :                                         NIL, NULL, parallel_workers, true,
    1592             :                                         partial_rows);
    1593        1472 :         add_partial_path(rel, (Path *) appendpath);
    1594             :     }
    1595             : 
    1596             :     /*
    1597             :      * Also build unparameterized ordered append paths based on the collected
    1598             :      * list of child pathkeys.
    1599             :      */
    1600       34166 :     if (subpaths_valid)
    1601       33854 :         generate_orderedappend_paths(root, rel, live_childrels,
    1602             :                                      all_child_pathkeys);
    1603             : 
    1604             :     /*
    1605             :      * Build Append paths for each parameterization seen among the child rels.
    1606             :      * (This may look pretty expensive, but in most cases of practical
    1607             :      * interest, the child rels will expose mostly the same parameterizations,
    1608             :      * so that not that many cases actually get considered here.)
    1609             :      *
    1610             :      * The Append node itself cannot enforce quals, so all qual checking must
    1611             :      * be done in the child paths.  This means that to have a parameterized
    1612             :      * Append path, we must have the exact same parameterization for each
    1613             :      * child path; otherwise some children might be failing to check the
    1614             :      * moved-down quals.  To make them match up, we can try to increase the
    1615             :      * parameterization of lesser-parameterized paths.
    1616             :      */
    1617       36392 :     foreach(l, all_child_outers)
    1618             :     {
    1619        2226 :         Relids      required_outer = (Relids) lfirst(l);
    1620             :         ListCell   *lcr;
    1621             : 
    1622             :         /* Select the child paths for an Append with this parameterization */
    1623        2226 :         subpaths = NIL;
    1624        2226 :         subpaths_valid = true;
    1625        8190 :         foreach(lcr, live_childrels)
    1626             :         {
    1627        5976 :             RelOptInfo *childrel = (RelOptInfo *) lfirst(lcr);
    1628             :             Path       *subpath;
    1629             : 
    1630        5976 :             if (childrel->pathlist == NIL)
    1631             :             {
    1632             :                 /* failed to make a suitable path for this child */
    1633           0 :                 subpaths_valid = false;
    1634           0 :                 break;
    1635             :             }
    1636             : 
    1637        5976 :             subpath = get_cheapest_parameterized_child_path(root,
    1638             :                                                             childrel,
    1639             :                                                             required_outer);
    1640        5976 :             if (subpath == NULL)
    1641             :             {
    1642             :                 /* failed to make a suitable path for this child */
    1643          12 :                 subpaths_valid = false;
    1644          12 :                 break;
    1645             :             }
    1646        5964 :             accumulate_append_subpath(subpath, &subpaths, NULL);
    1647             :         }
    1648             : 
    1649        2226 :         if (subpaths_valid)
    1650        2214 :             add_path(rel, (Path *)
    1651        2214 :                      create_append_path(root, rel, subpaths, NIL,
    1652             :                                         NIL, required_outer, 0, false,
    1653             :                                         -1));
    1654             :     }
    1655             : 
    1656             :     /*
    1657             :      * When there is only a single child relation, the Append path can inherit
    1658             :      * any ordering available for the child rel's path, so that it's useful to
    1659             :      * consider ordered partial paths.  Above we only considered the cheapest
    1660             :      * partial path for each child, but let's also make paths using any
    1661             :      * partial paths that have pathkeys.
    1662             :      */
    1663       34166 :     if (list_length(live_childrels) == 1)
    1664             :     {
    1665       13684 :         RelOptInfo *childrel = (RelOptInfo *) linitial(live_childrels);
    1666             : 
    1667             :         /* skip the cheapest partial path, since we already used that above */
    1668       13888 :         for_each_from(l, childrel->partial_pathlist, 1)
    1669             :         {
    1670         204 :             Path       *path = (Path *) lfirst(l);
    1671             :             AppendPath *appendpath;
    1672             : 
    1673             :             /* skip paths with no pathkeys. */
    1674         204 :             if (path->pathkeys == NIL)
    1675           0 :                 continue;
    1676             : 
    1677         204 :             appendpath = create_append_path(root, rel, NIL, list_make1(path),
    1678             :                                             NIL, NULL,
    1679             :                                             path->parallel_workers, true,
    1680             :                                             partial_rows);
    1681         204 :             add_partial_path(rel, (Path *) appendpath);
    1682             :         }
    1683             :     }
    1684       34166 : }
    1685             : 
    1686             : /*
    1687             :  * generate_orderedappend_paths
    1688             :  *      Generate ordered append paths for an append relation
    1689             :  *
    1690             :  * Usually we generate MergeAppend paths here, but there are some special
    1691             :  * cases where we can generate simple Append paths, because the subpaths
    1692             :  * can provide tuples in the required order already.
    1693             :  *
    1694             :  * We generate a path for each ordering (pathkey list) appearing in
    1695             :  * all_child_pathkeys.
    1696             :  *
    1697             :  * We consider both cheapest-startup and cheapest-total cases, ie, for each
    1698             :  * interesting ordering, collect all the cheapest startup subpaths and all the
    1699             :  * cheapest total paths, and build a suitable path for each case.
    1700             :  *
    1701             :  * We don't currently generate any parameterized ordered paths here.  While
    1702             :  * it would not take much more code here to do so, it's very unclear that it
    1703             :  * is worth the planning cycles to investigate such paths: there's little
    1704             :  * use for an ordered path on the inside of a nestloop.  In fact, it's likely
    1705             :  * that the current coding of add_path would reject such paths out of hand,
    1706             :  * because add_path gives no credit for sort ordering of parameterized paths,
    1707             :  * and a parameterized MergeAppend is going to be more expensive than the
    1708             :  * corresponding parameterized Append path.  If we ever try harder to support
    1709             :  * parameterized mergejoin plans, it might be worth adding support for
    1710             :  * parameterized paths here to feed such joins.  (See notes in
    1711             :  * optimizer/README for why that might not ever happen, though.)
    1712             :  */
    1713             : static void
    1714       33854 : generate_orderedappend_paths(PlannerInfo *root, RelOptInfo *rel,
    1715             :                              List *live_childrels,
    1716             :                              List *all_child_pathkeys)
    1717             : {
    1718             :     ListCell   *lcp;
    1719       33854 :     List       *partition_pathkeys = NIL;
    1720       33854 :     List       *partition_pathkeys_desc = NIL;
    1721       33854 :     bool        partition_pathkeys_partial = true;
    1722       33854 :     bool        partition_pathkeys_desc_partial = true;
    1723             : 
    1724             :     /*
    1725             :      * Some partitioned table setups may allow us to use an Append node
    1726             :      * instead of a MergeAppend.  This is possible in cases such as RANGE
    1727             :      * partitioned tables where it's guaranteed that an earlier partition must
    1728             :      * contain rows which come earlier in the sort order.  To detect whether
    1729             :      * this is relevant, build pathkey descriptions of the partition ordering,
    1730             :      * for both forward and reverse scans.
    1731             :      */
    1732       60238 :     if (rel->part_scheme != NULL && IS_SIMPLE_REL(rel) &&
    1733       26384 :         partitions_are_ordered(rel->boundinfo, rel->live_parts))
    1734             :     {
    1735       22006 :         partition_pathkeys = build_partition_pathkeys(root, rel,
    1736             :                                                       ForwardScanDirection,
    1737             :                                                       &partition_pathkeys_partial);
    1738             : 
    1739       22006 :         partition_pathkeys_desc = build_partition_pathkeys(root, rel,
    1740             :                                                            BackwardScanDirection,
    1741             :                                                            &partition_pathkeys_desc_partial);
    1742             : 
    1743             :         /*
    1744             :          * You might think we should truncate_useless_pathkeys here, but
    1745             :          * allowing partition keys which are a subset of the query's pathkeys
    1746             :          * can often be useful.  For example, consider a table partitioned by
    1747             :          * RANGE (a, b), and a query with ORDER BY a, b, c.  If we have child
    1748             :          * paths that can produce the a, b, c ordering (perhaps via indexes on
    1749             :          * (a, b, c)) then it works to consider the appendrel output as
    1750             :          * ordered by a, b, c.
    1751             :          */
    1752             :     }
    1753             : 
    1754             :     /* Now consider each interesting sort ordering */
    1755       39562 :     foreach(lcp, all_child_pathkeys)
    1756             :     {
    1757        5708 :         List       *pathkeys = (List *) lfirst(lcp);
    1758        5708 :         List       *startup_subpaths = NIL;
    1759        5708 :         List       *total_subpaths = NIL;
    1760        5708 :         List       *fractional_subpaths = NIL;
    1761        5708 :         bool        startup_neq_total = false;
    1762             :         bool        match_partition_order;
    1763             :         bool        match_partition_order_desc;
    1764             :         int         end_index;
    1765             :         int         first_index;
    1766             :         int         direction;
    1767             : 
    1768             :         /*
    1769             :          * Determine if this sort ordering matches any partition pathkeys we
    1770             :          * have, for both ascending and descending partition order.  If the
    1771             :          * partition pathkeys happen to be contained in pathkeys then it still
    1772             :          * works, as described above, providing that the partition pathkeys
    1773             :          * are complete and not just a prefix of the partition keys.  (In such
    1774             :          * cases we'll be relying on the child paths to have sorted the
    1775             :          * lower-order columns of the required pathkeys.)
    1776             :          */
    1777        5708 :         match_partition_order =
    1778        9298 :             pathkeys_contained_in(pathkeys, partition_pathkeys) ||
    1779        3726 :             (!partition_pathkeys_partial &&
    1780         136 :              pathkeys_contained_in(partition_pathkeys, pathkeys));
    1781             : 
    1782       12726 :         match_partition_order_desc = !match_partition_order &&
    1783        3524 :             (pathkeys_contained_in(pathkeys, partition_pathkeys_desc) ||
    1784        3534 :              (!partition_pathkeys_desc_partial &&
    1785          40 :               pathkeys_contained_in(partition_pathkeys_desc, pathkeys)));
    1786             : 
    1787             :         /*
    1788             :          * When the required pathkeys match the reverse of the partition
    1789             :          * order, we must build the list of paths in reverse starting with the
    1790             :          * last matching partition first.  We can get away without making any
    1791             :          * special cases for this in the loop below by just looping backward
    1792             :          * over the child relations in this case.
    1793             :          */
    1794        5708 :         if (match_partition_order_desc)
    1795             :         {
    1796             :             /* loop backward */
    1797          42 :             first_index = list_length(live_childrels) - 1;
    1798          42 :             end_index = -1;
    1799          42 :             direction = -1;
    1800             : 
    1801             :             /*
    1802             :              * Set this to true to save us having to check for
    1803             :              * match_partition_order_desc in the loop below.
    1804             :              */
    1805          42 :             match_partition_order = true;
    1806             :         }
    1807             :         else
    1808             :         {
    1809             :             /* for all other case, loop forward */
    1810        5666 :             first_index = 0;
    1811        5666 :             end_index = list_length(live_childrels);
    1812        5666 :             direction = 1;
    1813             :         }
    1814             : 
    1815             :         /* Select the child paths for this ordering... */
    1816       21048 :         for (int i = first_index; i != end_index; i += direction)
    1817             :         {
    1818       15340 :             RelOptInfo *childrel = list_nth_node(RelOptInfo, live_childrels, i);
    1819             :             Path       *cheapest_startup,
    1820             :                        *cheapest_total,
    1821       15340 :                        *cheapest_fractional = NULL;
    1822             : 
    1823             :             /* Locate the right paths, if they are available. */
    1824             :             cheapest_startup =
    1825       15340 :                 get_cheapest_path_for_pathkeys(childrel->pathlist,
    1826             :                                                pathkeys,
    1827             :                                                NULL,
    1828             :                                                STARTUP_COST,
    1829             :                                                false);
    1830             :             cheapest_total =
    1831       15340 :                 get_cheapest_path_for_pathkeys(childrel->pathlist,
    1832             :                                                pathkeys,
    1833             :                                                NULL,
    1834             :                                                TOTAL_COST,
    1835             :                                                false);
    1836             : 
    1837             :             /*
    1838             :              * If we can't find any paths with the right order just use the
    1839             :              * cheapest-total path; we'll have to sort it later.
    1840             :              */
    1841       15340 :             if (cheapest_startup == NULL || cheapest_total == NULL)
    1842             :             {
    1843         268 :                 cheapest_startup = cheapest_total =
    1844             :                     childrel->cheapest_total_path;
    1845             :                 /* Assert we do have an unparameterized path for this child */
    1846             :                 Assert(cheapest_total->param_info == NULL);
    1847             :             }
    1848             : 
    1849             :             /*
    1850             :              * When building a fractional path, determine a cheapest
    1851             :              * fractional path for each child relation too. Looking at startup
    1852             :              * and total costs is not enough, because the cheapest fractional
    1853             :              * path may be dominated by two separate paths (one for startup,
    1854             :              * one for total).
    1855             :              *
    1856             :              * When needed (building fractional path), determine the cheapest
    1857             :              * fractional path too.
    1858             :              */
    1859       15340 :             if (root->tuple_fraction > 0)
    1860             :             {
    1861         668 :                 double      path_fraction = (1.0 / root->tuple_fraction);
    1862             : 
    1863             :                 cheapest_fractional =
    1864         668 :                     get_cheapest_fractional_path_for_pathkeys(childrel->pathlist,
    1865             :                                                               pathkeys,
    1866             :                                                               NULL,
    1867             :                                                               path_fraction);
    1868             : 
    1869             :                 /*
    1870             :                  * If we found no path with matching pathkeys, use the
    1871             :                  * cheapest total path instead.
    1872             :                  *
    1873             :                  * XXX We might consider partially sorted paths too (with an
    1874             :                  * incremental sort on top). But we'd have to build all the
    1875             :                  * incremental paths, do the costing etc.
    1876             :                  */
    1877         668 :                 if (!cheapest_fractional)
    1878          44 :                     cheapest_fractional = cheapest_total;
    1879             :             }
    1880             : 
    1881             :             /*
    1882             :              * Notice whether we actually have different paths for the
    1883             :              * "cheapest" and "total" cases; frequently there will be no point
    1884             :              * in two create_merge_append_path() calls.
    1885             :              */
    1886       15340 :             if (cheapest_startup != cheapest_total)
    1887          48 :                 startup_neq_total = true;
    1888             : 
    1889             :             /*
    1890             :              * Collect the appropriate child paths.  The required logic varies
    1891             :              * for the Append and MergeAppend cases.
    1892             :              */
    1893       15340 :             if (match_partition_order)
    1894             :             {
    1895             :                 /*
    1896             :                  * We're going to make a plain Append path.  We don't need
    1897             :                  * most of what accumulate_append_subpath would do, but we do
    1898             :                  * want to cut out child Appends or MergeAppends if they have
    1899             :                  * just a single subpath (and hence aren't doing anything
    1900             :                  * useful).
    1901             :                  */
    1902        5978 :                 cheapest_startup = get_singleton_append_subpath(cheapest_startup);
    1903        5978 :                 cheapest_total = get_singleton_append_subpath(cheapest_total);
    1904             : 
    1905        5978 :                 startup_subpaths = lappend(startup_subpaths, cheapest_startup);
    1906        5978 :                 total_subpaths = lappend(total_subpaths, cheapest_total);
    1907             : 
    1908        5978 :                 if (cheapest_fractional)
    1909             :                 {
    1910         120 :                     cheapest_fractional = get_singleton_append_subpath(cheapest_fractional);
    1911         120 :                     fractional_subpaths = lappend(fractional_subpaths, cheapest_fractional);
    1912             :                 }
    1913             :             }
    1914             :             else
    1915             :             {
    1916             :                 /*
    1917             :                  * Otherwise, rely on accumulate_append_subpath to collect the
    1918             :                  * child paths for the MergeAppend.
    1919             :                  */
    1920        9362 :                 accumulate_append_subpath(cheapest_startup,
    1921             :                                           &startup_subpaths, NULL);
    1922        9362 :                 accumulate_append_subpath(cheapest_total,
    1923             :                                           &total_subpaths, NULL);
    1924             : 
    1925        9362 :                 if (cheapest_fractional)
    1926         548 :                     accumulate_append_subpath(cheapest_fractional,
    1927             :                                               &fractional_subpaths, NULL);
    1928             :             }
    1929             :         }
    1930             : 
    1931             :         /* ... and build the Append or MergeAppend paths */
    1932        5708 :         if (match_partition_order)
    1933             :         {
    1934             :             /* We only need Append */
    1935        2226 :             add_path(rel, (Path *) create_append_path(root,
    1936             :                                                       rel,
    1937             :                                                       startup_subpaths,
    1938             :                                                       NIL,
    1939             :                                                       pathkeys,
    1940             :                                                       NULL,
    1941             :                                                       0,
    1942             :                                                       false,
    1943             :                                                       -1));
    1944        2226 :             if (startup_neq_total)
    1945           0 :                 add_path(rel, (Path *) create_append_path(root,
    1946             :                                                           rel,
    1947             :                                                           total_subpaths,
    1948             :                                                           NIL,
    1949             :                                                           pathkeys,
    1950             :                                                           NULL,
    1951             :                                                           0,
    1952             :                                                           false,
    1953             :                                                           -1));
    1954             : 
    1955        2226 :             if (fractional_subpaths)
    1956          60 :                 add_path(rel, (Path *) create_append_path(root,
    1957             :                                                           rel,
    1958             :                                                           fractional_subpaths,
    1959             :                                                           NIL,
    1960             :                                                           pathkeys,
    1961             :                                                           NULL,
    1962             :                                                           0,
    1963             :                                                           false,
    1964             :                                                           -1));
    1965             :         }
    1966             :         else
    1967             :         {
    1968             :             /* We need MergeAppend */
    1969        3482 :             add_path(rel, (Path *) create_merge_append_path(root,
    1970             :                                                             rel,
    1971             :                                                             startup_subpaths,
    1972             :                                                             pathkeys,
    1973             :                                                             NULL));
    1974        3482 :             if (startup_neq_total)
    1975          24 :                 add_path(rel, (Path *) create_merge_append_path(root,
    1976             :                                                                 rel,
    1977             :                                                                 total_subpaths,
    1978             :                                                                 pathkeys,
    1979             :                                                                 NULL));
    1980             : 
    1981        3482 :             if (fractional_subpaths)
    1982         196 :                 add_path(rel, (Path *) create_merge_append_path(root,
    1983             :                                                                 rel,
    1984             :                                                                 fractional_subpaths,
    1985             :                                                                 pathkeys,
    1986             :                                                                 NULL));
    1987             :         }
    1988             :     }
    1989       33854 : }
    1990             : 
    1991             : /*
    1992             :  * get_cheapest_parameterized_child_path
    1993             :  *      Get cheapest path for this relation that has exactly the requested
    1994             :  *      parameterization.
    1995             :  *
    1996             :  * Returns NULL if unable to create such a path.
    1997             :  */
    1998             : static Path *
    1999        5976 : get_cheapest_parameterized_child_path(PlannerInfo *root, RelOptInfo *rel,
    2000             :                                       Relids required_outer)
    2001             : {
    2002             :     Path       *cheapest;
    2003             :     ListCell   *lc;
    2004             : 
    2005             :     /*
    2006             :      * Look up the cheapest existing path with no more than the needed
    2007             :      * parameterization.  If it has exactly the needed parameterization, we're
    2008             :      * done.
    2009             :      */
    2010        5976 :     cheapest = get_cheapest_path_for_pathkeys(rel->pathlist,
    2011             :                                               NIL,
    2012             :                                               required_outer,
    2013             :                                               TOTAL_COST,
    2014             :                                               false);
    2015             :     Assert(cheapest != NULL);
    2016        5976 :     if (bms_equal(PATH_REQ_OUTER(cheapest), required_outer))
    2017        5684 :         return cheapest;
    2018             : 
    2019             :     /*
    2020             :      * Otherwise, we can "reparameterize" an existing path to match the given
    2021             :      * parameterization, which effectively means pushing down additional
    2022             :      * joinquals to be checked within the path's scan.  However, some existing
    2023             :      * paths might check the available joinquals already while others don't;
    2024             :      * therefore, it's not clear which existing path will be cheapest after
    2025             :      * reparameterization.  We have to go through them all and find out.
    2026             :      */
    2027         292 :     cheapest = NULL;
    2028        1012 :     foreach(lc, rel->pathlist)
    2029             :     {
    2030         720 :         Path       *path = (Path *) lfirst(lc);
    2031             : 
    2032             :         /* Can't use it if it needs more than requested parameterization */
    2033         720 :         if (!bms_is_subset(PATH_REQ_OUTER(path), required_outer))
    2034          24 :             continue;
    2035             : 
    2036             :         /*
    2037             :          * Reparameterization can only increase the path's cost, so if it's
    2038             :          * already more expensive than the current cheapest, forget it.
    2039             :          */
    2040        1080 :         if (cheapest != NULL &&
    2041         384 :             compare_path_costs(cheapest, path, TOTAL_COST) <= 0)
    2042         312 :             continue;
    2043             : 
    2044             :         /* Reparameterize if needed, then recheck cost */
    2045         384 :         if (!bms_equal(PATH_REQ_OUTER(path), required_outer))
    2046             :         {
    2047         308 :             path = reparameterize_path(root, path, required_outer, 1.0);
    2048         308 :             if (path == NULL)
    2049          32 :                 continue;       /* failed to reparameterize this one */
    2050             :             Assert(bms_equal(PATH_REQ_OUTER(path), required_outer));
    2051             : 
    2052         276 :             if (cheapest != NULL &&
    2053           0 :                 compare_path_costs(cheapest, path, TOTAL_COST) <= 0)
    2054           0 :                 continue;
    2055             :         }
    2056             : 
    2057             :         /* We have a new best path */
    2058         352 :         cheapest = path;
    2059             :     }
    2060             : 
    2061             :     /* Return the best path, or NULL if we found no suitable candidate */
    2062         292 :     return cheapest;
    2063             : }
    2064             : 
    2065             : /*
    2066             :  * accumulate_append_subpath
    2067             :  *      Add a subpath to the list being built for an Append or MergeAppend.
    2068             :  *
    2069             :  * It's possible that the child is itself an Append or MergeAppend path, in
    2070             :  * which case we can "cut out the middleman" and just add its child paths to
    2071             :  * our own list.  (We don't try to do this earlier because we need to apply
    2072             :  * both levels of transformation to the quals.)
    2073             :  *
    2074             :  * Note that if we omit a child MergeAppend in this way, we are effectively
    2075             :  * omitting a sort step, which seems fine: if the parent is to be an Append,
    2076             :  * its result would be unsorted anyway, while if the parent is to be a
    2077             :  * MergeAppend, there's no point in a separate sort on a child.
    2078             :  *
    2079             :  * Normally, either path is a partial path and subpaths is a list of partial
    2080             :  * paths, or else path is a non-partial plan and subpaths is a list of those.
    2081             :  * However, if path is a parallel-aware Append, then we add its partial path
    2082             :  * children to subpaths and the rest to special_subpaths.  If the latter is
    2083             :  * NULL, we don't flatten the path at all (unless it contains only partial
    2084             :  * paths).
    2085             :  */
    2086             : static void
    2087      193820 : accumulate_append_subpath(Path *path, List **subpaths, List **special_subpaths)
    2088             : {
    2089      193820 :     if (IsA(path, AppendPath))
    2090             :     {
    2091       14024 :         AppendPath *apath = (AppendPath *) path;
    2092             : 
    2093       14024 :         if (!apath->path.parallel_aware || apath->first_partial_path == 0)
    2094             :         {
    2095       13832 :             *subpaths = list_concat(*subpaths, apath->subpaths);
    2096       13832 :             return;
    2097             :         }
    2098         192 :         else if (special_subpaths != NULL)
    2099             :         {
    2100             :             List       *new_special_subpaths;
    2101             : 
    2102             :             /* Split Parallel Append into partial and non-partial subpaths */
    2103          96 :             *subpaths = list_concat(*subpaths,
    2104          96 :                                     list_copy_tail(apath->subpaths,
    2105             :                                                    apath->first_partial_path));
    2106          96 :             new_special_subpaths = list_copy_head(apath->subpaths,
    2107             :                                                   apath->first_partial_path);
    2108          96 :             *special_subpaths = list_concat(*special_subpaths,
    2109             :                                             new_special_subpaths);
    2110          96 :             return;
    2111             :         }
    2112             :     }
    2113      179796 :     else if (IsA(path, MergeAppendPath))
    2114             :     {
    2115         620 :         MergeAppendPath *mpath = (MergeAppendPath *) path;
    2116             : 
    2117         620 :         *subpaths = list_concat(*subpaths, mpath->subpaths);
    2118         620 :         return;
    2119             :     }
    2120             : 
    2121      179272 :     *subpaths = lappend(*subpaths, path);
    2122             : }
    2123             : 
    2124             : /*
    2125             :  * get_singleton_append_subpath
    2126             :  *      Returns the single subpath of an Append/MergeAppend, or just
    2127             :  *      return 'path' if it's not a single sub-path Append/MergeAppend.
    2128             :  *
    2129             :  * Note: 'path' must not be a parallel-aware path.
    2130             :  */
    2131             : static Path *
    2132       12076 : get_singleton_append_subpath(Path *path)
    2133             : {
    2134             :     Assert(!path->parallel_aware);
    2135             : 
    2136       12076 :     if (IsA(path, AppendPath))
    2137             :     {
    2138         340 :         AppendPath *apath = (AppendPath *) path;
    2139             : 
    2140         340 :         if (list_length(apath->subpaths) == 1)
    2141         156 :             return (Path *) linitial(apath->subpaths);
    2142             :     }
    2143       11736 :     else if (IsA(path, MergeAppendPath))
    2144             :     {
    2145         252 :         MergeAppendPath *mpath = (MergeAppendPath *) path;
    2146             : 
    2147         252 :         if (list_length(mpath->subpaths) == 1)
    2148           0 :             return (Path *) linitial(mpath->subpaths);
    2149             :     }
    2150             : 
    2151       11920 :     return path;
    2152             : }
    2153             : 
    2154             : /*
    2155             :  * set_dummy_rel_pathlist
    2156             :  *    Build a dummy path for a relation that's been excluded by constraints
    2157             :  *
    2158             :  * Rather than inventing a special "dummy" path type, we represent this as an
    2159             :  * AppendPath with no members (see also IS_DUMMY_APPEND/IS_DUMMY_REL macros).
    2160             :  *
    2161             :  * (See also mark_dummy_rel, which does basically the same thing, but is
    2162             :  * typically used to change a rel into dummy state after we already made
    2163             :  * paths for it.)
    2164             :  */
    2165             : static void
    2166         988 : set_dummy_rel_pathlist(RelOptInfo *rel)
    2167             : {
    2168             :     /* Set dummy size estimates --- we leave attr_widths[] as zeroes */
    2169         988 :     rel->rows = 0;
    2170         988 :     rel->reltarget->width = 0;
    2171             : 
    2172             :     /* Discard any pre-existing paths; no further need for them */
    2173         988 :     rel->pathlist = NIL;
    2174         988 :     rel->partial_pathlist = NIL;
    2175             : 
    2176             :     /* Set up the dummy path */
    2177         988 :     add_path(rel, (Path *) create_append_path(NULL, rel, NIL, NIL,
    2178             :                                               NIL, rel->lateral_relids,
    2179             :                                               0, false, -1));
    2180             : 
    2181             :     /*
    2182             :      * We set the cheapest-path fields immediately, just in case they were
    2183             :      * pointing at some discarded path.  This is redundant in current usage
    2184             :      * because set_rel_pathlist will do it later, but it's cheap so we keep it
    2185             :      * for safety and consistency with mark_dummy_rel.
    2186             :      */
    2187         988 :     set_cheapest(rel);
    2188         988 : }
    2189             : 
    2190             : /*
    2191             :  * find_window_run_conditions
    2192             :  *      Determine if 'wfunc' is really a WindowFunc and call its prosupport
    2193             :  *      function to determine the function's monotonic properties.  We then
    2194             :  *      see if 'opexpr' can be used to short-circuit execution.
    2195             :  *
    2196             :  * For example row_number() over (order by ...) always produces a value one
    2197             :  * higher than the previous.  If someone has a window function in a subquery
    2198             :  * and has a WHERE clause in the outer query to filter rows <= 10, then we may
    2199             :  * as well stop processing the windowagg once the row number reaches 11.  Here
    2200             :  * we check if 'opexpr' might help us to stop doing needless extra processing
    2201             :  * in WindowAgg nodes.
    2202             :  *
    2203             :  * '*keep_original' is set to true if the caller should also use 'opexpr' for
    2204             :  * its original purpose.  This is set to false if the caller can assume that
    2205             :  * the run condition will handle all of the required filtering.
    2206             :  *
    2207             :  * Returns true if 'opexpr' was found to be useful and was added to the
    2208             :  * WindowFunc's runCondition.  We also set *keep_original accordingly and add
    2209             :  * 'attno' to *run_cond_attrs offset by FirstLowInvalidHeapAttributeNumber.
    2210             :  * If the 'opexpr' cannot be used then we set *keep_original to true and
    2211             :  * return false.
    2212             :  */
    2213             : static bool
    2214         234 : find_window_run_conditions(Query *subquery, RangeTblEntry *rte, Index rti,
    2215             :                            AttrNumber attno, WindowFunc *wfunc, OpExpr *opexpr,
    2216             :                            bool wfunc_left, bool *keep_original,
    2217             :                            Bitmapset **run_cond_attrs)
    2218             : {
    2219             :     Oid         prosupport;
    2220             :     Expr       *otherexpr;
    2221             :     SupportRequestWFuncMonotonic req;
    2222             :     SupportRequestWFuncMonotonic *res;
    2223             :     WindowClause *wclause;
    2224             :     List       *opinfos;
    2225             :     OpExpr     *runopexpr;
    2226             :     Oid         runoperator;
    2227             :     ListCell   *lc;
    2228             : 
    2229         234 :     *keep_original = true;
    2230             : 
    2231         234 :     while (IsA(wfunc, RelabelType))
    2232           0 :         wfunc = (WindowFunc *) ((RelabelType *) wfunc)->arg;
    2233             : 
    2234             :     /* we can only work with window functions */
    2235         234 :     if (!IsA(wfunc, WindowFunc))
    2236          24 :         return false;
    2237             : 
    2238             :     /* can't use it if there are subplans in the WindowFunc */
    2239         210 :     if (contain_subplans((Node *) wfunc))
    2240           6 :         return false;
    2241             : 
    2242         204 :     prosupport = get_func_support(wfunc->winfnoid);
    2243             : 
    2244             :     /* Check if there's a support function for 'wfunc' */
    2245         204 :     if (!OidIsValid(prosupport))
    2246          18 :         return false;
    2247             : 
    2248             :     /* get the Expr from the other side of the OpExpr */
    2249         186 :     if (wfunc_left)
    2250         162 :         otherexpr = lsecond(opexpr->args);
    2251             :     else
    2252          24 :         otherexpr = linitial(opexpr->args);
    2253             : 
    2254             :     /*
    2255             :      * The value being compared must not change during the evaluation of the
    2256             :      * window partition.
    2257             :      */
    2258         186 :     if (!is_pseudo_constant_clause((Node *) otherexpr))
    2259           0 :         return false;
    2260             : 
    2261             :     /* find the window clause belonging to the window function */
    2262         186 :     wclause = (WindowClause *) list_nth(subquery->windowClause,
    2263         186 :                                         wfunc->winref - 1);
    2264             : 
    2265         186 :     req.type = T_SupportRequestWFuncMonotonic;
    2266         186 :     req.window_func = wfunc;
    2267         186 :     req.window_clause = wclause;
    2268             : 
    2269             :     /* call the support function */
    2270             :     res = (SupportRequestWFuncMonotonic *)
    2271         186 :         DatumGetPointer(OidFunctionCall1(prosupport,
    2272             :                                          PointerGetDatum(&req)));
    2273             : 
    2274             :     /*
    2275             :      * Nothing to do if the function is neither monotonically increasing nor
    2276             :      * monotonically decreasing.
    2277             :      */
    2278         186 :     if (res == NULL || res->monotonic == MONOTONICFUNC_NONE)
    2279           0 :         return false;
    2280             : 
    2281         186 :     runopexpr = NULL;
    2282         186 :     runoperator = InvalidOid;
    2283         186 :     opinfos = get_op_btree_interpretation(opexpr->opno);
    2284             : 
    2285         186 :     foreach(lc, opinfos)
    2286             :     {
    2287         186 :         OpBtreeInterpretation *opinfo = (OpBtreeInterpretation *) lfirst(lc);
    2288         186 :         int         strategy = opinfo->strategy;
    2289             : 
    2290             :         /* handle < / <= */
    2291         186 :         if (strategy == BTLessStrategyNumber ||
    2292             :             strategy == BTLessEqualStrategyNumber)
    2293             :         {
    2294             :             /*
    2295             :              * < / <= is supported for monotonically increasing functions in
    2296             :              * the form <wfunc> op <pseudoconst> and <pseudoconst> op <wfunc>
    2297             :              * for monotonically decreasing functions.
    2298             :              */
    2299         132 :             if ((wfunc_left && (res->monotonic & MONOTONICFUNC_INCREASING)) ||
    2300          18 :                 (!wfunc_left && (res->monotonic & MONOTONICFUNC_DECREASING)))
    2301             :             {
    2302         120 :                 *keep_original = false;
    2303         120 :                 runopexpr = opexpr;
    2304         120 :                 runoperator = opexpr->opno;
    2305             :             }
    2306         132 :             break;
    2307             :         }
    2308             :         /* handle > / >= */
    2309          54 :         else if (strategy == BTGreaterStrategyNumber ||
    2310             :                  strategy == BTGreaterEqualStrategyNumber)
    2311             :         {
    2312             :             /*
    2313             :              * > / >= is supported for monotonically decreasing functions in
    2314             :              * the form <wfunc> op <pseudoconst> and <pseudoconst> op <wfunc>
    2315             :              * for monotonically increasing functions.
    2316             :              */
    2317          18 :             if ((wfunc_left && (res->monotonic & MONOTONICFUNC_DECREASING)) ||
    2318          12 :                 (!wfunc_left && (res->monotonic & MONOTONICFUNC_INCREASING)))
    2319             :             {
    2320          18 :                 *keep_original = false;
    2321          18 :                 runopexpr = opexpr;
    2322          18 :                 runoperator = opexpr->opno;
    2323             :             }
    2324          18 :             break;
    2325             :         }
    2326             :         /* handle = */
    2327          36 :         else if (strategy == BTEqualStrategyNumber)
    2328             :         {
    2329             :             int16       newstrategy;
    2330             : 
    2331             :             /*
    2332             :              * When both monotonically increasing and decreasing then the
    2333             :              * return value of the window function will be the same each time.
    2334             :              * We can simply use 'opexpr' as the run condition without
    2335             :              * modifying it.
    2336             :              */
    2337          36 :             if ((res->monotonic & MONOTONICFUNC_BOTH) == MONOTONICFUNC_BOTH)
    2338             :             {
    2339           6 :                 *keep_original = false;
    2340           6 :                 runopexpr = opexpr;
    2341           6 :                 runoperator = opexpr->opno;
    2342           6 :                 break;
    2343             :             }
    2344             : 
    2345             :             /*
    2346             :              * When monotonically increasing we make a qual with <wfunc> <=
    2347             :              * <value> or <value> >= <wfunc> in order to filter out values
    2348             :              * which are above the value in the equality condition.  For
    2349             :              * monotonically decreasing functions we want to filter values
    2350             :              * below the value in the equality condition.
    2351             :              */
    2352          30 :             if (res->monotonic & MONOTONICFUNC_INCREASING)
    2353          30 :                 newstrategy = wfunc_left ? BTLessEqualStrategyNumber : BTGreaterEqualStrategyNumber;
    2354             :             else
    2355           0 :                 newstrategy = wfunc_left ? BTGreaterEqualStrategyNumber : BTLessEqualStrategyNumber;
    2356             : 
    2357             :             /* We must keep the original equality qual */
    2358          30 :             *keep_original = true;
    2359          30 :             runopexpr = opexpr;
    2360             : 
    2361             :             /* determine the operator to use for the WindowFuncRunCondition */
    2362          30 :             runoperator = get_opfamily_member(opinfo->opfamily_id,
    2363             :                                               opinfo->oplefttype,
    2364             :                                               opinfo->oprighttype,
    2365             :                                               newstrategy);
    2366          30 :             break;
    2367             :         }
    2368             :     }
    2369             : 
    2370         186 :     if (runopexpr != NULL)
    2371             :     {
    2372             :         WindowFuncRunCondition *wfuncrc;
    2373             : 
    2374         174 :         wfuncrc = makeNode(WindowFuncRunCondition);
    2375         174 :         wfuncrc->opno = runoperator;
    2376         174 :         wfuncrc->inputcollid = runopexpr->inputcollid;
    2377         174 :         wfuncrc->wfunc_left = wfunc_left;
    2378         174 :         wfuncrc->arg = copyObject(otherexpr);
    2379             : 
    2380         174 :         wfunc->runCondition = lappend(wfunc->runCondition, wfuncrc);
    2381             : 
    2382             :         /* record that this attno was used in a run condition */
    2383         174 :         *run_cond_attrs = bms_add_member(*run_cond_attrs,
    2384             :                                          attno - FirstLowInvalidHeapAttributeNumber);
    2385         174 :         return true;
    2386             :     }
    2387             : 
    2388             :     /* unsupported OpExpr */
    2389          12 :     return false;
    2390             : }
    2391             : 
    2392             : /*
    2393             :  * check_and_push_window_quals
    2394             :  *      Check if 'clause' is a qual that can be pushed into a WindowFunc
    2395             :  *      as a 'runCondition' qual.  These, when present, allow some unnecessary
    2396             :  *      work to be skipped during execution.
    2397             :  *
    2398             :  * 'run_cond_attrs' will be populated with all targetlist resnos of subquery
    2399             :  * targets (offset by FirstLowInvalidHeapAttributeNumber) that we pushed
    2400             :  * window quals for.
    2401             :  *
    2402             :  * Returns true if the caller still must keep the original qual or false if
    2403             :  * the caller can safely ignore the original qual because the WindowAgg node
    2404             :  * will use the runCondition to stop returning tuples.
    2405             :  */
    2406             : static bool
    2407         246 : check_and_push_window_quals(Query *subquery, RangeTblEntry *rte, Index rti,
    2408             :                             Node *clause, Bitmapset **run_cond_attrs)
    2409             : {
    2410         246 :     OpExpr     *opexpr = (OpExpr *) clause;
    2411         246 :     bool        keep_original = true;
    2412             :     Var        *var1;
    2413             :     Var        *var2;
    2414             : 
    2415             :     /* We're only able to use OpExprs with 2 operands */
    2416         246 :     if (!IsA(opexpr, OpExpr))
    2417          18 :         return true;
    2418             : 
    2419         228 :     if (list_length(opexpr->args) != 2)
    2420           0 :         return true;
    2421             : 
    2422             :     /*
    2423             :      * Currently, we restrict this optimization to strict OpExprs.  The reason
    2424             :      * for this is that during execution, once the runcondition becomes false,
    2425             :      * we stop evaluating WindowFuncs.  To avoid leaving around stale window
    2426             :      * function result values, we set them to NULL.  Having only strict
    2427             :      * OpExprs here ensures that we properly filter out the tuples with NULLs
    2428             :      * in the top-level WindowAgg.
    2429             :      */
    2430         228 :     set_opfuncid(opexpr);
    2431         228 :     if (!func_strict(opexpr->opfuncid))
    2432           0 :         return true;
    2433             : 
    2434             :     /*
    2435             :      * Check for plain Vars that reference window functions in the subquery.
    2436             :      * If we find any, we'll ask find_window_run_conditions() if 'opexpr' can
    2437             :      * be used as part of the run condition.
    2438             :      */
    2439             : 
    2440             :     /* Check the left side of the OpExpr */
    2441         228 :     var1 = linitial(opexpr->args);
    2442         228 :     if (IsA(var1, Var) && var1->varattno > 0)
    2443             :     {
    2444         192 :         TargetEntry *tle = list_nth(subquery->targetList, var1->varattno - 1);
    2445         192 :         WindowFunc *wfunc = (WindowFunc *) tle->expr;
    2446             : 
    2447         192 :         if (find_window_run_conditions(subquery, rte, rti, tle->resno, wfunc,
    2448             :                                        opexpr, true, &keep_original,
    2449             :                                        run_cond_attrs))
    2450         156 :             return keep_original;
    2451             :     }
    2452             : 
    2453             :     /* and check the right side */
    2454          72 :     var2 = lsecond(opexpr->args);
    2455          72 :     if (IsA(var2, Var) && var2->varattno > 0)
    2456             :     {
    2457          42 :         TargetEntry *tle = list_nth(subquery->targetList, var2->varattno - 1);
    2458          42 :         WindowFunc *wfunc = (WindowFunc *) tle->expr;
    2459             : 
    2460          42 :         if (find_window_run_conditions(subquery, rte, rti, tle->resno, wfunc,
    2461             :                                        opexpr, false, &keep_original,
    2462             :                                        run_cond_attrs))
    2463          18 :             return keep_original;
    2464             :     }
    2465             : 
    2466          54 :     return true;
    2467             : }
    2468             : 
    2469             : /*
    2470             :  * set_subquery_pathlist
    2471             :  *      Generate SubqueryScan access paths for a subquery RTE
    2472             :  *
    2473             :  * We don't currently support generating parameterized paths for subqueries
    2474             :  * by pushing join clauses down into them; it seems too expensive to re-plan
    2475             :  * the subquery multiple times to consider different alternatives.
    2476             :  * (XXX that could stand to be reconsidered, now that we use Paths.)
    2477             :  * So the paths made here will be parameterized if the subquery contains
    2478             :  * LATERAL references, otherwise not.  As long as that's true, there's no need
    2479             :  * for a separate set_subquery_size phase: just make the paths right away.
    2480             :  */
    2481             : static void
    2482        7076 : set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel,
    2483             :                       Index rti, RangeTblEntry *rte)
    2484             : {
    2485        7076 :     Query      *parse = root->parse;
    2486        7076 :     Query      *subquery = rte->subquery;
    2487             :     bool        trivial_pathtarget;
    2488             :     Relids      required_outer;
    2489             :     pushdown_safety_info safetyInfo;
    2490             :     double      tuple_fraction;
    2491             :     RelOptInfo *sub_final_rel;
    2492        7076 :     Bitmapset  *run_cond_attrs = NULL;
    2493             :     ListCell   *lc;
    2494             : 
    2495             :     /*
    2496             :      * Must copy the Query so that planning doesn't mess up the RTE contents
    2497             :      * (really really need to fix the planner to not scribble on its input,
    2498             :      * someday ... but see remove_unused_subquery_outputs to start with).
    2499             :      */
    2500        7076 :     subquery = copyObject(subquery);
    2501             : 
    2502             :     /*
    2503             :      * If it's a LATERAL subquery, it might contain some Vars of the current
    2504             :      * query level, requiring it to be treated as parameterized, even though
    2505             :      * we don't support pushing down join quals into subqueries.
    2506             :      */
    2507        7076 :     required_outer = rel->lateral_relids;
    2508             : 
    2509             :     /*
    2510             :      * Zero out result area for subquery_is_pushdown_safe, so that it can set
    2511             :      * flags as needed while recursing.  In particular, we need a workspace
    2512             :      * for keeping track of the reasons why columns are unsafe to reference.
    2513             :      * These reasons are stored in the bits inside unsafeFlags[i] when we
    2514             :      * discover reasons that column i of the subquery is unsafe to be used in
    2515             :      * a pushed-down qual.
    2516             :      */
    2517        7076 :     memset(&safetyInfo, 0, sizeof(safetyInfo));
    2518        7076 :     safetyInfo.unsafeFlags = (unsigned char *)
    2519        7076 :         palloc0((list_length(subquery->targetList) + 1) * sizeof(unsigned char));
    2520             : 
    2521             :     /*
    2522             :      * If the subquery has the "security_barrier" flag, it means the subquery
    2523             :      * originated from a view that must enforce row-level security.  Then we
    2524             :      * must not push down quals that contain leaky functions.  (Ideally this
    2525             :      * would be checked inside subquery_is_pushdown_safe, but since we don't
    2526             :      * currently pass the RTE to that function, we must do it here.)
    2527             :      */
    2528        7076 :     safetyInfo.unsafeLeaky = rte->security_barrier;
    2529             : 
    2530             :     /*
    2531             :      * If there are any restriction clauses that have been attached to the
    2532             :      * subquery relation, consider pushing them down to become WHERE or HAVING
    2533             :      * quals of the subquery itself.  This transformation is useful because it
    2534             :      * may allow us to generate a better plan for the subquery than evaluating
    2535             :      * all the subquery output rows and then filtering them.
    2536             :      *
    2537             :      * There are several cases where we cannot push down clauses. Restrictions
    2538             :      * involving the subquery are checked by subquery_is_pushdown_safe().
    2539             :      * Restrictions on individual clauses are checked by
    2540             :      * qual_is_pushdown_safe().  Also, we don't want to push down
    2541             :      * pseudoconstant clauses; better to have the gating node above the
    2542             :      * subquery.
    2543             :      *
    2544             :      * Non-pushed-down clauses will get evaluated as qpquals of the
    2545             :      * SubqueryScan node.
    2546             :      *
    2547             :      * XXX Are there any cases where we want to make a policy decision not to
    2548             :      * push down a pushable qual, because it'd result in a worse plan?
    2549             :      */
    2550        8408 :     if (rel->baserestrictinfo != NIL &&
    2551        1332 :         subquery_is_pushdown_safe(subquery, subquery, &safetyInfo))
    2552             :     {
    2553             :         /* OK to consider pushing down individual quals */
    2554        1192 :         List       *upperrestrictlist = NIL;
    2555             :         ListCell   *l;
    2556             : 
    2557        2760 :         foreach(l, rel->baserestrictinfo)
    2558             :         {
    2559        1568 :             RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
    2560        1568 :             Node       *clause = (Node *) rinfo->clause;
    2561             : 
    2562        1568 :             if (rinfo->pseudoconstant)
    2563             :             {
    2564           4 :                 upperrestrictlist = lappend(upperrestrictlist, rinfo);
    2565           4 :                 continue;
    2566             :             }
    2567             : 
    2568        1564 :             switch (qual_is_pushdown_safe(subquery, rti, rinfo, &safetyInfo))
    2569             :             {
    2570         894 :                 case PUSHDOWN_SAFE:
    2571             :                     /* Push it down */
    2572         894 :                     subquery_push_qual(subquery, rte, rti, clause);
    2573         894 :                     break;
    2574             : 
    2575         246 :                 case PUSHDOWN_WINDOWCLAUSE_RUNCOND:
    2576             : 
    2577             :                     /*
    2578             :                      * Since we can't push the qual down into the subquery,
    2579             :                      * check if it happens to reference a window function.  If
    2580             :                      * so then it might be useful to use for the WindowAgg's
    2581             :                      * runCondition.
    2582             :                      */
    2583         492 :                     if (!subquery->hasWindowFuncs ||
    2584         246 :                         check_and_push_window_quals(subquery, rte, rti, clause,
    2585             :                                                     &run_cond_attrs))
    2586             :                     {
    2587             :                         /*
    2588             :                          * subquery has no window funcs or the clause is not a
    2589             :                          * suitable window run condition qual or it is, but
    2590             :                          * the original must also be kept in the upper query.
    2591             :                          */
    2592         102 :                         upperrestrictlist = lappend(upperrestrictlist, rinfo);
    2593             :                     }
    2594         246 :                     break;
    2595             : 
    2596         424 :                 case PUSHDOWN_UNSAFE:
    2597         424 :                     upperrestrictlist = lappend(upperrestrictlist, rinfo);
    2598         424 :                     break;
    2599             :             }
    2600        1568 :         }
    2601        1192 :         rel->baserestrictinfo = upperrestrictlist;
    2602             :         /* We don't bother recomputing baserestrict_min_security */
    2603             :     }
    2604             : 
    2605        7076 :     pfree(safetyInfo.unsafeFlags);
    2606             : 
    2607             :     /*
    2608             :      * The upper query might not use all the subquery's output columns; if
    2609             :      * not, we can simplify.  Pass the attributes that were pushed down into
    2610             :      * WindowAgg run conditions to ensure we don't accidentally think those
    2611             :      * are unused.
    2612             :      */
    2613        7076 :     remove_unused_subquery_outputs(subquery, rel, run_cond_attrs);
    2614             : 
    2615             :     /*
    2616             :      * We can safely pass the outer tuple_fraction down to the subquery if the
    2617             :      * outer level has no joining, aggregation, or sorting to do. Otherwise
    2618             :      * we'd better tell the subquery to plan for full retrieval. (XXX This
    2619             :      * could probably be made more intelligent ...)
    2620             :      */
    2621        7076 :     if (parse->hasAggs ||
    2622        6498 :         parse->groupClause ||
    2623        6492 :         parse->groupingSets ||
    2624        6492 :         root->hasHavingQual ||
    2625        6492 :         parse->distinctClause ||
    2626       10466 :         parse->sortClause ||
    2627        4398 :         bms_membership(root->all_baserels) == BMS_MULTIPLE)
    2628        3794 :         tuple_fraction = 0.0;   /* default case */
    2629             :     else
    2630        3282 :         tuple_fraction = root->tuple_fraction;
    2631             : 
    2632             :     /* plan_params should not be in use in current query level */
    2633             :     Assert(root->plan_params == NIL);
    2634             : 
    2635             :     /* Generate a subroot and Paths for the subquery */
    2636        7076 :     rel->subroot = subquery_planner(root->glob, subquery, root, false,
    2637             :                                     tuple_fraction, NULL);
    2638             : 
    2639             :     /* Isolate the params needed by this specific subplan */
    2640        7076 :     rel->subplan_params = root->plan_params;
    2641        7076 :     root->plan_params = NIL;
    2642             : 
    2643             :     /*
    2644             :      * It's possible that constraint exclusion proved the subquery empty. If
    2645             :      * so, it's desirable to produce an unadorned dummy path so that we will
    2646             :      * recognize appropriate optimizations at this query level.
    2647             :      */
    2648        7076 :     sub_final_rel = fetch_upper_rel(rel->subroot, UPPERREL_FINAL, NULL);
    2649             : 
    2650        7076 :     if (IS_DUMMY_REL(sub_final_rel))
    2651             :     {
    2652         108 :         set_dummy_rel_pathlist(rel);
    2653         108 :         return;
    2654             :     }
    2655             : 
    2656             :     /*
    2657             :      * Mark rel with estimated output rows, width, etc.  Note that we have to
    2658             :      * do this before generating outer-query paths, else cost_subqueryscan is
    2659             :      * not happy.
    2660             :      */
    2661        6968 :     set_subquery_size_estimates(root, rel);
    2662             : 
    2663             :     /*
    2664             :      * Also detect whether the reltarget is trivial, so that we can pass that
    2665             :      * info to cost_subqueryscan (rather than re-deriving it multiple times).
    2666             :      * It's trivial if it fetches all the subplan output columns in order.
    2667             :      */
    2668        6968 :     if (list_length(rel->reltarget->exprs) != list_length(subquery->targetList))
    2669        1828 :         trivial_pathtarget = false;
    2670             :     else
    2671             :     {
    2672        5140 :         trivial_pathtarget = true;
    2673       14708 :         foreach(lc, rel->reltarget->exprs)
    2674             :         {
    2675        9872 :             Node       *node = (Node *) lfirst(lc);
    2676             :             Var        *var;
    2677             : 
    2678        9872 :             if (!IsA(node, Var))
    2679             :             {
    2680           0 :                 trivial_pathtarget = false;
    2681           0 :                 break;
    2682             :             }
    2683        9872 :             var = (Var *) node;
    2684        9872 :             if (var->varno != rti ||
    2685        9872 :                 var->varattno != foreach_current_index(lc) + 1)
    2686             :             {
    2687         304 :                 trivial_pathtarget = false;
    2688         304 :                 break;
    2689             :             }
    2690             :         }
    2691             :     }
    2692             : 
    2693             :     /*
    2694             :      * For each Path that subquery_planner produced, make a SubqueryScanPath
    2695             :      * in the outer query.
    2696             :      */
    2697       14574 :     foreach(lc, sub_final_rel->pathlist)
    2698             :     {
    2699        7606 :         Path       *subpath = (Path *) lfirst(lc);
    2700             :         List       *pathkeys;
    2701             : 
    2702             :         /* Convert subpath's pathkeys to outer representation */
    2703        7606 :         pathkeys = convert_subquery_pathkeys(root,
    2704             :                                              rel,
    2705             :                                              subpath->pathkeys,
    2706             :                                              make_tlist_from_pathtarget(subpath->pathtarget));
    2707             : 
    2708             :         /* Generate outer path using this subpath */
    2709        7606 :         add_path(rel, (Path *)
    2710        7606 :                  create_subqueryscan_path(root, rel, subpath,
    2711             :                                           trivial_pathtarget,
    2712             :                                           pathkeys, required_outer));
    2713             :     }
    2714             : 
    2715             :     /* If outer rel allows parallelism, do same for partial paths. */
    2716        6968 :     if (rel->consider_parallel && bms_is_empty(required_outer))
    2717             :     {
    2718             :         /* If consider_parallel is false, there should be no partial paths. */
    2719             :         Assert(sub_final_rel->consider_parallel ||
    2720             :                sub_final_rel->partial_pathlist == NIL);
    2721             : 
    2722             :         /* Same for partial paths. */
    2723        3850 :         foreach(lc, sub_final_rel->partial_pathlist)
    2724             :         {
    2725          42 :             Path       *subpath = (Path *) lfirst(lc);
    2726             :             List       *pathkeys;
    2727             : 
    2728             :             /* Convert subpath's pathkeys to outer representation */
    2729          42 :             pathkeys = convert_subquery_pathkeys(root,
    2730             :                                                  rel,
    2731             :                                                  subpath->pathkeys,
    2732             :                                                  make_tlist_from_pathtarget(subpath->pathtarget));
    2733             : 
    2734             :             /* Generate outer path using this subpath */
    2735          42 :             add_partial_path(rel, (Path *)
    2736          42 :                              create_subqueryscan_path(root, rel, subpath,
    2737             :                                                       trivial_pathtarget,
    2738             :                                                       pathkeys,
    2739             :                                                       required_outer));
    2740             :         }
    2741             :     }
    2742             : }
    2743             : 
    2744             : /*
    2745             :  * set_function_pathlist
    2746             :  *      Build the (single) access path for a function RTE
    2747             :  */
    2748             : static void
    2749       38920 : set_function_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
    2750             : {
    2751             :     Relids      required_outer;
    2752       38920 :     List       *pathkeys = NIL;
    2753             : 
    2754             :     /*
    2755             :      * We don't support pushing join clauses into the quals of a function
    2756             :      * scan, but it could still have required parameterization due to LATERAL
    2757             :      * refs in the function expression.
    2758             :      */
    2759       38920 :     required_outer = rel->lateral_relids;
    2760             : 
    2761             :     /*
    2762             :      * The result is considered unordered unless ORDINALITY was used, in which
    2763             :      * case it is ordered by the ordinal column (the last one).  See if we
    2764             :      * care, by checking for uses of that Var in equivalence classes.
    2765             :      */
    2766       38920 :     if (rte->funcordinality)
    2767             :     {
    2768         624 :         AttrNumber  ordattno = rel->max_attr;
    2769         624 :         Var        *var = NULL;
    2770             :         ListCell   *lc;
    2771             : 
    2772             :         /*
    2773             :          * Is there a Var for it in rel's targetlist?  If not, the query did
    2774             :          * not reference the ordinality column, or at least not in any way
    2775             :          * that would be interesting for sorting.
    2776             :          */
    2777        1778 :         foreach(lc, rel->reltarget->exprs)
    2778             :         {
    2779        1772 :             Var        *node = (Var *) lfirst(lc);
    2780             : 
    2781             :             /* checking varno/varlevelsup is just paranoia */
    2782        1772 :             if (IsA(node, Var) &&
    2783        1772 :                 node->varattno == ordattno &&
    2784         618 :                 node->varno == rel->relid &&
    2785         618 :                 node->varlevelsup == 0)
    2786             :             {
    2787         618 :                 var = node;
    2788         618 :                 break;
    2789             :             }
    2790             :         }
    2791             : 
    2792             :         /*
    2793             :          * Try to build pathkeys for this Var with int8 sorting.  We tell
    2794             :          * build_expression_pathkey not to build any new equivalence class; if
    2795             :          * the Var isn't already mentioned in some EC, it means that nothing
    2796             :          * cares about the ordering.
    2797             :          */
    2798         624 :         if (var)
    2799         618 :             pathkeys = build_expression_pathkey(root,
    2800             :                                                 (Expr *) var,
    2801             :                                                 Int8LessOperator,
    2802             :                                                 rel->relids,
    2803             :                                                 false);
    2804             :     }
    2805             : 
    2806             :     /* Generate appropriate path */
    2807       38920 :     add_path(rel, create_functionscan_path(root, rel,
    2808             :                                            pathkeys, required_outer));
    2809       38920 : }
    2810             : 
    2811             : /*
    2812             :  * set_values_pathlist
    2813             :  *      Build the (single) access path for a VALUES RTE
    2814             :  */
    2815             : static void
    2816        7654 : set_values_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
    2817             : {
    2818             :     Relids      required_outer;
    2819             : 
    2820             :     /*
    2821             :      * We don't support pushing join clauses into the quals of a values scan,
    2822             :      * but it could still have required parameterization due to LATERAL refs
    2823             :      * in the values expressions.
    2824             :      */
    2825        7654 :     required_outer = rel->lateral_relids;
    2826             : 
    2827             :     /* Generate appropriate path */
    2828        7654 :     add_path(rel, create_valuesscan_path(root, rel, required_outer));
    2829        7654 : }
    2830             : 
    2831             : /*
    2832             :  * set_tablefunc_pathlist
    2833             :  *      Build the (single) access path for a table func RTE
    2834             :  */
    2835             : static void
    2836         548 : set_tablefunc_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
    2837             : {
    2838             :     Relids      required_outer;
    2839             : 
    2840             :     /*
    2841             :      * We don't support pushing join clauses into the quals of a tablefunc
    2842             :      * scan, but it could still have required parameterization due to LATERAL
    2843             :      * refs in the function expression.
    2844             :      */
    2845         548 :     required_outer = rel->lateral_relids;
    2846             : 
    2847             :     /* Generate appropriate path */
    2848         548 :     add_path(rel, create_tablefuncscan_path(root, rel,
    2849             :                                             required_outer));
    2850         548 : }
    2851             : 
    2852             : /*
    2853             :  * set_cte_pathlist
    2854             :  *      Build the (single) access path for a non-self-reference CTE RTE
    2855             :  *
    2856             :  * There's no need for a separate set_cte_size phase, since we don't
    2857             :  * support join-qual-parameterized paths for CTEs.
    2858             :  */
    2859             : static void
    2860        3208 : set_cte_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
    2861             : {
    2862             :     Path       *ctepath;
    2863             :     Plan       *cteplan;
    2864             :     PlannerInfo *cteroot;
    2865             :     Index       levelsup;
    2866             :     List       *pathkeys;
    2867             :     int         ndx;
    2868             :     ListCell   *lc;
    2869             :     int         plan_id;
    2870             :     Relids      required_outer;
    2871             : 
    2872             :     /*
    2873             :      * Find the referenced CTE, and locate the path and plan previously made
    2874             :      * for it.
    2875             :      */
    2876        3208 :     levelsup = rte->ctelevelsup;
    2877        3208 :     cteroot = root;
    2878        5718 :     while (levelsup-- > 0)
    2879             :     {
    2880        2510 :         cteroot = cteroot->parent_root;
    2881        2510 :         if (!cteroot)           /* shouldn't happen */
    2882           0 :             elog(ERROR, "bad levelsup for CTE \"%s\"", rte->ctename);
    2883             :     }
    2884             : 
    2885             :     /*
    2886             :      * Note: cte_plan_ids can be shorter than cteList, if we are still working
    2887             :      * on planning the CTEs (ie, this is a side-reference from another CTE).
    2888             :      * So we mustn't use forboth here.
    2889             :      */
    2890        3208 :     ndx = 0;
    2891        4660 :     foreach(lc, cteroot->parse->cteList)
    2892             :     {
    2893        4660 :         CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
    2894             : 
    2895        4660 :         if (strcmp(cte->ctename, rte->ctename) == 0)
    2896        3208 :             break;
    2897        1452 :         ndx++;
    2898             :     }
    2899        3208 :     if (lc == NULL)             /* shouldn't happen */
    2900           0 :         elog(ERROR, "could not find CTE \"%s\"", rte->ctename);
    2901        3208 :     if (ndx >= list_length(cteroot->cte_plan_ids))
    2902           0 :         elog(ERROR, "could not find plan for CTE \"%s\"", rte->ctename);
    2903        3208 :     plan_id = list_nth_int(cteroot->cte_plan_ids, ndx);
    2904        3208 :     if (plan_id <= 0)
    2905           0 :         elog(ERROR, "no plan was made for CTE \"%s\"", rte->ctename);
    2906             : 
    2907             :     Assert(list_length(root->glob->subpaths) == list_length(root->glob->subplans));
    2908        3208 :     ctepath = (Path *) list_nth(root->glob->subpaths, plan_id - 1);
    2909        3208 :     cteplan = (Plan *) list_nth(root->glob->subplans, plan_id - 1);
    2910             : 
    2911             :     /* Mark rel with estimated output rows, width, etc */
    2912        3208 :     set_cte_size_estimates(root, rel, cteplan->plan_rows);
    2913             : 
    2914             :     /* Convert the ctepath's pathkeys to outer query's representation */
    2915        3208 :     pathkeys = convert_subquery_pathkeys(root,
    2916             :                                          rel,
    2917             :                                          ctepath->pathkeys,
    2918             :                                          cteplan->targetlist);
    2919             : 
    2920             :     /*
    2921             :      * We don't support pushing join clauses into the quals of a CTE scan, but
    2922             :      * it could still have required parameterization due to LATERAL refs in
    2923             :      * its tlist.
    2924             :      */
    2925        3208 :     required_outer = rel->lateral_relids;
    2926             : 
    2927             :     /* Generate appropriate path */
    2928        3208 :     add_path(rel, create_ctescan_path(root, rel, pathkeys, required_outer));
    2929        3208 : }
    2930             : 
    2931             : /*
    2932             :  * set_namedtuplestore_pathlist
    2933             :  *      Build the (single) access path for a named tuplestore RTE
    2934             :  *
    2935             :  * There's no need for a separate set_namedtuplestore_size phase, since we
    2936             :  * don't support join-qual-parameterized paths for tuplestores.
    2937             :  */
    2938             : static void
    2939         442 : set_namedtuplestore_pathlist(PlannerInfo *root, RelOptInfo *rel,
    2940             :                              RangeTblEntry *rte)
    2941             : {
    2942             :     Relids      required_outer;
    2943             : 
    2944             :     /* Mark rel with estimated output rows, width, etc */
    2945         442 :     set_namedtuplestore_size_estimates(root, rel);
    2946             : 
    2947             :     /*
    2948             :      * We don't support pushing join clauses into the quals of a tuplestore
    2949             :      * scan, but it could still have required parameterization due to LATERAL
    2950             :      * refs in its tlist.
    2951             :      */
    2952         442 :     required_outer = rel->lateral_relids;
    2953             : 
    2954             :     /* Generate appropriate path */
    2955         442 :     add_path(rel, create_namedtuplestorescan_path(root, rel, required_outer));
    2956         442 : }
    2957             : 
    2958             : /*
    2959             :  * set_result_pathlist
    2960             :  *      Build the (single) access path for an RTE_RESULT RTE
    2961             :  *
    2962             :  * There's no need for a separate set_result_size phase, since we
    2963             :  * don't support join-qual-parameterized paths for these RTEs.
    2964             :  */
    2965             : static void
    2966        1506 : set_result_pathlist(PlannerInfo *root, RelOptInfo *rel,
    2967             :                     RangeTblEntry *rte)
    2968             : {
    2969             :     Relids      required_outer;
    2970             : 
    2971             :     /* Mark rel with estimated output rows, width, etc */
    2972        1506 :     set_result_size_estimates(root, rel);
    2973             : 
    2974             :     /*
    2975             :      * We don't support pushing join clauses into the quals of a Result scan,
    2976             :      * but it could still have required parameterization due to LATERAL refs
    2977             :      * in its tlist.
    2978             :      */
    2979        1506 :     required_outer = rel->lateral_relids;
    2980             : 
    2981             :     /* Generate appropriate path */
    2982        1506 :     add_path(rel, create_resultscan_path(root, rel, required_outer));
    2983        1506 : }
    2984             : 
    2985             : /*
    2986             :  * set_worktable_pathlist
    2987             :  *      Build the (single) access path for a self-reference CTE RTE
    2988             :  *
    2989             :  * There's no need for a separate set_worktable_size phase, since we don't
    2990             :  * support join-qual-parameterized paths for CTEs.
    2991             :  */
    2992             : static void
    2993         806 : set_worktable_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
    2994             : {
    2995             :     Path       *ctepath;
    2996             :     PlannerInfo *cteroot;
    2997             :     Index       levelsup;
    2998             :     Relids      required_outer;
    2999             : 
    3000             :     /*
    3001             :      * We need to find the non-recursive term's path, which is in the plan
    3002             :      * level that's processing the recursive UNION, which is one level *below*
    3003             :      * where the CTE comes from.
    3004             :      */
    3005         806 :     levelsup = rte->ctelevelsup;
    3006         806 :     if (levelsup == 0)          /* shouldn't happen */
    3007           0 :         elog(ERROR, "bad levelsup for CTE \"%s\"", rte->ctename);
    3008         806 :     levelsup--;
    3009         806 :     cteroot = root;
    3010        1832 :     while (levelsup-- > 0)
    3011             :     {
    3012        1026 :         cteroot = cteroot->parent_root;
    3013        1026 :         if (!cteroot)           /* shouldn't happen */
    3014           0 :             elog(ERROR, "bad levelsup for CTE \"%s\"", rte->ctename);
    3015             :     }
    3016         806 :     ctepath = cteroot->non_recursive_path;
    3017         806 :     if (!ctepath)               /* shouldn't happen */
    3018           0 :         elog(ERROR, "could not find path for CTE \"%s\"", rte->ctename);
    3019             : 
    3020             :     /* Mark rel with estimated output rows, width, etc */
    3021         806 :     set_cte_size_estimates(root, rel, ctepath->rows);
    3022             : 
    3023             :     /*
    3024             :      * We don't support pushing join clauses into the quals of a worktable
    3025             :      * scan, but it could still have required parameterization due to LATERAL
    3026             :      * refs in its tlist.  (I'm not sure this is actually possible given the
    3027             :      * restrictions on recursive references, but it's easy enough to support.)
    3028             :      */
    3029         806 :     required_outer = rel->lateral_relids;
    3030             : 
    3031             :     /* Generate appropriate path */
    3032         806 :     add_path(rel, create_worktablescan_path(root, rel, required_outer));
    3033         806 : }
    3034             : 
    3035             : /*
    3036             :  * generate_gather_paths
    3037             :  *      Generate parallel access paths for a relation by pushing a Gather or
    3038             :  *      Gather Merge on top of a partial path.
    3039             :  *
    3040             :  * This must not be called until after we're done creating all partial paths
    3041             :  * for the specified relation.  (Otherwise, add_partial_path might delete a
    3042             :  * path that some GatherPath or GatherMergePath has a reference to.)
    3043             :  *
    3044             :  * If we're generating paths for a scan or join relation, override_rows will
    3045             :  * be false, and we'll just use the relation's size estimate.  When we're
    3046             :  * being called for a partially-grouped or partially-distinct path, though, we
    3047             :  * need to override the rowcount estimate.  (It's not clear that the
    3048             :  * particular value we're using here is actually best, but the underlying rel
    3049             :  * has no estimate so we must do something.)
    3050             :  */
    3051             : void
    3052       16066 : generate_gather_paths(PlannerInfo *root, RelOptInfo *rel, bool override_rows)
    3053             : {
    3054             :     Path       *cheapest_partial_path;
    3055             :     Path       *simple_gather_path;
    3056             :     ListCell   *lc;
    3057             :     double      rows;
    3058       16066 :     double     *rowsp = NULL;
    3059             : 
    3060             :     /* If there are no partial paths, there's nothing to do here. */
    3061       16066 :     if (rel->partial_pathlist == NIL)
    3062           0 :         return;
    3063             : 
    3064             :     /* Should we override the rel's rowcount estimate? */
    3065       16066 :     if (override_rows)
    3066        1744 :         rowsp = &rows;
    3067             : 
    3068             :     /*
    3069             :      * The output of Gather is always unsorted, so there's only one partial
    3070             :      * path of interest: the cheapest one.  That will be the one at the front
    3071             :      * of partial_pathlist because of the way add_partial_path works.
    3072             :      */
    3073       16066 :     cheapest_partial_path = linitial(rel->partial_pathlist);
    3074       16066 :     rows =
    3075       16066 :         cheapest_partial_path->rows * cheapest_partial_path->parallel_workers;
    3076             :     simple_gather_path = (Path *)
    3077       16066 :         create_gather_path(root, rel, cheapest_partial_path, rel->reltarget,
    3078             :                            NULL, rowsp);
    3079       16066 :     add_path(rel, simple_gather_path);
    3080             : 
    3081             :     /*
    3082             :      * For each useful ordering, we can consider an order-preserving Gather
    3083             :      * Merge.
    3084             :      */
    3085       33430 :     foreach(lc, rel->partial_pathlist)
    3086             :     {
    3087       17364 :         Path       *subpath = (Path *) lfirst(lc);
    3088             :         GatherMergePath *path;
    3089             : 
    3090       17364 :         if (subpath->pathkeys == NIL)
    3091       15752 :             continue;
    3092             : 
    3093        1612 :         rows = subpath->rows * subpath->parallel_workers;
    3094        1612 :         path = create_gather_merge_path(root, rel, subpath, rel->reltarget,
    3095             :                                         subpath->pathkeys, NULL, rowsp);
    3096        1612 :         add_path(rel, &path->path);
    3097             :     }
    3098             : }
    3099             : 
    3100             : /*
    3101             :  * get_useful_pathkeys_for_relation
    3102             :  *      Determine which orderings of a relation might be useful.
    3103             :  *
    3104             :  * Getting data in sorted order can be useful either because the requested
    3105             :  * order matches the final output ordering for the overall query we're
    3106             :  * planning, or because it enables an efficient merge join.  Here, we try
    3107             :  * to figure out which pathkeys to consider.
    3108             :  *
    3109             :  * This allows us to do incremental sort on top of an index scan under a gather
    3110             :  * merge node, i.e. parallelized.
    3111             :  *
    3112             :  * If the require_parallel_safe is true, we also require the expressions to
    3113             :  * be parallel safe (which allows pushing the sort below Gather Merge).
    3114             :  *
    3115             :  * XXX At the moment this can only ever return a list with a single element,
    3116             :  * because it looks at query_pathkeys only. So we might return the pathkeys
    3117             :  * directly, but it seems plausible we'll want to consider other orderings
    3118             :  * in the future. For example, we might want to consider pathkeys useful for
    3119             :  * merge joins.
    3120             :  */
    3121             : static List *
    3122       16066 : get_useful_pathkeys_for_relation(PlannerInfo *root, RelOptInfo *rel,
    3123             :                                  bool require_parallel_safe)
    3124             : {
    3125       16066 :     List       *useful_pathkeys_list = NIL;
    3126             : 
    3127             :     /*
    3128             :      * Considering query_pathkeys is always worth it, because it might allow
    3129             :      * us to avoid a total sort when we have a partially presorted path
    3130             :      * available or to push the total sort into the parallel portion of the
    3131             :      * query.
    3132             :      */
    3133       16066 :     if (root->query_pathkeys)
    3134             :     {
    3135             :         ListCell   *lc;
    3136        6806 :         int         npathkeys = 0;  /* useful pathkeys */
    3137             : 
    3138       14674 :         foreach(lc, root->query_pathkeys)
    3139             :         {
    3140        9836 :             PathKey    *pathkey = (PathKey *) lfirst(lc);
    3141        9836 :             EquivalenceClass *pathkey_ec = pathkey->pk_eclass;
    3142             : 
    3143             :             /*
    3144             :              * We can only build a sort for pathkeys that contain a
    3145             :              * safe-to-compute-early EC member computable from the current
    3146             :              * relation's reltarget, so ignore the remainder of the list as
    3147             :              * soon as we find a pathkey without such a member.
    3148             :              *
    3149             :              * It's still worthwhile to return any prefix of the pathkeys list
    3150             :              * that meets this requirement, as we may be able to do an
    3151             :              * incremental sort.
    3152             :              *
    3153             :              * If requested, ensure the sort expression is parallel-safe too.
    3154             :              */
    3155        9836 :             if (!relation_can_be_sorted_early(root, rel, pathkey_ec,
    3156             :                                               require_parallel_safe))
    3157        1968 :                 break;
    3158             : 
    3159        7868 :             npathkeys++;
    3160             :         }
    3161             : 
    3162             :         /*
    3163             :          * The whole query_pathkeys list matches, so append it directly, to
    3164             :          * allow comparing pathkeys easily by comparing list pointer. If we
    3165             :          * have to truncate the pathkeys, we gotta do a copy though.
    3166             :          */
    3167        6806 :         if (npathkeys == list_length(root->query_pathkeys))
    3168        4838 :             useful_pathkeys_list = lappend(useful_pathkeys_list,
    3169        4838 :                                            root->query_pathkeys);
    3170        1968 :         else if (npathkeys > 0)
    3171         444 :             useful_pathkeys_list = lappend(useful_pathkeys_list,
    3172         444 :                                            list_copy_head(root->query_pathkeys,
    3173             :                                                           npathkeys));
    3174             :     }
    3175             : 
    3176       16066 :     return useful_pathkeys_list;
    3177             : }
    3178             : 
    3179             : /*
    3180             :  * generate_useful_gather_paths
    3181             :  *      Generate parallel access paths for a relation by pushing a Gather or
    3182             :  *      Gather Merge on top of a partial path.
    3183             :  *
    3184             :  * Unlike plain generate_gather_paths, this looks both at pathkeys of input
    3185             :  * paths (aiming to preserve the ordering), but also considers ordering that
    3186             :  * might be useful for nodes above the gather merge node, and tries to add
    3187             :  * a sort (regular or incremental) to provide that.
    3188             :  */
    3189             : void
    3190      488938 : generate_useful_gather_paths(PlannerInfo *root, RelOptInfo *rel, bool override_rows)
    3191             : {
    3192             :     ListCell   *lc;
    3193             :     double      rows;
    3194      488938 :     double     *rowsp = NULL;
    3195      488938 :     List       *useful_pathkeys_list = NIL;
    3196      488938 :     Path       *cheapest_partial_path = NULL;
    3197             : 
    3198             :     /* If there are no partial paths, there's nothing to do here. */
    3199      488938 :     if (rel->partial_pathlist == NIL)
    3200      472872 :         return;
    3201             : 
    3202             :     /* Should we override the rel's rowcount estimate? */
    3203       16066 :     if (override_rows)
    3204        1744 :         rowsp = &rows;
    3205             : 
    3206             :     /* generate the regular gather (merge) paths */
    3207       16066 :     generate_gather_paths(root, rel, override_rows);
    3208             : 
    3209             :     /* consider incremental sort for interesting orderings */
    3210       16066 :     useful_pathkeys_list = get_useful_pathkeys_for_relation(root, rel, true);
    3211             : 
    3212             :     /* used for explicit (full) sort paths */
    3213       16066 :     cheapest_partial_path = linitial(rel->partial_pathlist);
    3214             : 
    3215             :     /*
    3216             :      * Consider sorted paths for each interesting ordering. We generate both
    3217             :      * incremental and full sort.
    3218             :      */
    3219       21348 :     foreach(lc, useful_pathkeys_list)
    3220             :     {
    3221        5282 :         List       *useful_pathkeys = lfirst(lc);
    3222             :         ListCell   *lc2;
    3223             :         bool        is_sorted;
    3224             :         int         presorted_keys;
    3225             : 
    3226       11748 :         foreach(lc2, rel->partial_pathlist)
    3227             :         {
    3228        6466 :             Path       *subpath = (Path *) lfirst(lc2);
    3229             :             GatherMergePath *path;
    3230             : 
    3231        6466 :             is_sorted = pathkeys_count_contained_in(useful_pathkeys,
    3232             :                                                     subpath->pathkeys,
    3233             :                                                     &presorted_keys);
    3234             : 
    3235             :             /*
    3236             :              * We don't need to consider the case where a subpath is already
    3237             :              * fully sorted because generate_gather_paths already creates a
    3238             :              * gather merge path for every subpath that has pathkeys present.
    3239             :              *
    3240             :              * But since the subpath is already sorted, we know we don't need
    3241             :              * to consider adding a sort (full or incremental) on top of it,
    3242             :              * so we can continue here.
    3243             :              */
    3244        6466 :             if (is_sorted)
    3245        1204 :                 continue;
    3246             : 
    3247             :             /*
    3248             :              * Try at least sorting the cheapest path and also try
    3249             :              * incrementally sorting any path which is partially sorted
    3250             :              * already (no need to deal with paths which have presorted keys
    3251             :              * when incremental sort is disabled unless it's the cheapest
    3252             :              * input path).
    3253             :              */
    3254        5262 :             if (subpath != cheapest_partial_path &&
    3255         198 :                 (presorted_keys == 0 || !enable_incremental_sort))
    3256          54 :                 continue;
    3257             : 
    3258             :             /*
    3259             :              * Consider regular sort for any path that's not presorted or if
    3260             :              * incremental sort is disabled.  We've no need to consider both
    3261             :              * sort and incremental sort on the same path.  We assume that
    3262             :              * incremental sort is always faster when there are presorted
    3263             :              * keys.
    3264             :              *
    3265             :              * This is not redundant with the gather paths created in
    3266             :              * generate_gather_paths, because that doesn't generate ordered
    3267             :              * output. Here we add an explicit sort to match the useful
    3268             :              * ordering.
    3269             :              */
    3270        5208 :             if (presorted_keys == 0 || !enable_incremental_sort)
    3271             :             {
    3272        5052 :                 subpath = (Path *) create_sort_path(root,
    3273             :                                                     rel,
    3274             :                                                     subpath,
    3275             :                                                     useful_pathkeys,
    3276             :                                                     -1.0);
    3277        5052 :                 rows = subpath->rows * subpath->parallel_workers;
    3278             :             }
    3279             :             else
    3280         156 :                 subpath = (Path *) create_incremental_sort_path(root,
    3281             :                                                                 rel,
    3282             :                                                                 subpath,
    3283             :                                                                 useful_pathkeys,
    3284             :                                                                 presorted_keys,
    3285             :                                                                 -1);
    3286        5208 :             path = create_gather_merge_path(root, rel,
    3287             :                                             subpath,
    3288        5208 :                                             rel->reltarget,
    3289             :                                             subpath->pathkeys,
    3290             :                                             NULL,
    3291             :                                             rowsp);
    3292             : 
    3293        5208 :             add_path(rel, &path->path);
    3294             :         }
    3295             :     }
    3296             : }
    3297             : 
    3298             : /*
    3299             :  * make_rel_from_joinlist
    3300             :  *    Build access paths using a "joinlist" to guide the join path search.
    3301             :  *
    3302             :  * See comments for deconstruct_jointree() for definition of the joinlist
    3303             :  * data structure.
    3304             :  */
    3305             : static RelOptInfo *
    3306      269596 : make_rel_from_joinlist(PlannerInfo *root, List *joinlist)
    3307             : {
    3308             :     int         levels_needed;
    3309             :     List       *initial_rels;
    3310             :     ListCell   *jl;
    3311             : 
    3312             :     /*
    3313             :      * Count the number of child joinlist nodes.  This is the depth of the
    3314             :      * dynamic-programming algorithm we must employ to consider all ways of
    3315             :      * joining the child nodes.
    3316             :      */
    3317      269596 :     levels_needed = list_length(joinlist);
    3318             : 
    3319      269596 :     if (levels_needed <= 0)
    3320           0 :         return NULL;            /* nothing to do? */
    3321             : 
    3322             :     /*
    3323             :      * Construct a list of rels corresponding to the child joinlist nodes.
    3324             :      * This may contain both base rels and rels constructed according to
    3325             :      * sub-joinlists.
    3326             :      */
    3327      269596 :     initial_rels = NIL;
    3328      645800 :     foreach(jl, joinlist)
    3329             :     {
    3330      376204 :         Node       *jlnode = (Node *) lfirst(jl);
    3331             :         RelOptInfo *thisrel;
    3332             : 
    3333      376204 :         if (IsA(jlnode, RangeTblRef))
    3334             :         {
    3335      372982 :             int         varno = ((RangeTblRef *) jlnode)->rtindex;
    3336             : 
    3337      372982 :             thisrel = find_base_rel(root, varno);
    3338             :         }
    3339        3222 :         else if (IsA(jlnode, List))
    3340             :         {
    3341             :             /* Recurse to handle subproblem */
    3342        3222 :             thisrel = make_rel_from_joinlist(root, (List *) jlnode);
    3343             :         }
    3344             :         else
    3345             :         {
    3346           0 :             elog(ERROR, "unrecognized joinlist node type: %d",
    3347             :                  (int) nodeTag(jlnode));
    3348             :             thisrel = NULL;     /* keep compiler quiet */
    3349             :         }
    3350             : 
    3351      376204 :         initial_rels = lappend(initial_rels, thisrel);
    3352             :     }
    3353             : 
    3354      269596 :     if (levels_needed == 1)
    3355             :     {
    3356             :         /*
    3357             :          * Single joinlist node, so we're done.
    3358             :          */
    3359      192382 :         return (RelOptInfo *) linitial(initial_rels);
    3360             :     }
    3361             :     else
    3362             :     {
    3363             :         /*
    3364             :          * Consider the different orders in which we could join the rels,
    3365             :          * using a plugin, GEQO, or the regular join search code.
    3366             :          *
    3367             :          * We put the initial_rels list into a PlannerInfo field because
    3368             :          * has_legal_joinclause() needs to look at it (ugly :-().
    3369             :          */
    3370       77214 :         root->initial_rels = initial_rels;
    3371             : 
    3372       77214 :         if (join_search_hook)
    3373           0 :             return (*join_search_hook) (root, levels_needed, initial_rels);
    3374       77214 :         else if (enable_geqo && levels_needed >= geqo_threshold)
    3375           6 :             return geqo(root, levels_needed, initial_rels);
    3376             :         else
    3377       77208 :             return standard_join_search(root, levels_needed, initial_rels);
    3378             :     }
    3379             : }
    3380             : 
    3381             : /*
    3382             :  * standard_join_search
    3383             :  *    Find possible joinpaths for a query by successively finding ways
    3384             :  *    to join component relations into join relations.
    3385             :  *
    3386             :  * 'levels_needed' is the number of iterations needed, ie, the number of
    3387             :  *      independent jointree items in the query.  This is > 1.
    3388             :  *
    3389             :  * 'initial_rels' is a list of RelOptInfo nodes for each independent
    3390             :  *      jointree item.  These are the components to be joined together.
    3391             :  *      Note that levels_needed == list_length(initial_rels).
    3392             :  *
    3393             :  * Returns the final level of join relations, i.e., the relation that is
    3394             :  * the result of joining all the original relations together.
    3395             :  * At least one implementation path must be provided for this relation and
    3396             :  * all required sub-relations.
    3397             :  *
    3398             :  * To support loadable plugins that modify planner behavior by changing the
    3399             :  * join searching algorithm, we provide a hook variable that lets a plugin
    3400             :  * replace or supplement this function.  Any such hook must return the same
    3401             :  * final join relation as the standard code would, but it might have a
    3402             :  * different set of implementation paths attached, and only the sub-joinrels
    3403             :  * needed for these paths need have been instantiated.
    3404             :  *
    3405             :  * Note to plugin authors: the functions invoked during standard_join_search()
    3406             :  * modify root->join_rel_list and root->join_rel_hash.  If you want to do more
    3407             :  * than one join-order search, you'll probably need to save and restore the
    3408             :  * original states of those data structures.  See geqo_eval() for an example.
    3409             :  */
    3410             : RelOptInfo *
    3411       77208 : standard_join_search(PlannerInfo *root, int levels_needed, List *initial_rels)
    3412             : {
    3413             :     int         lev;
    3414             :     RelOptInfo *rel;
    3415             : 
    3416             :     /*
    3417             :      * This function cannot be invoked recursively within any one planning
    3418             :      * problem, so join_rel_level[] can't be in use already.
    3419             :      */
    3420             :     Assert(root->join_rel_level == NULL);
    3421             : 
    3422             :     /*
    3423             :      * We employ a simple "dynamic programming" algorithm: we first find all
    3424             :      * ways to build joins of two jointree items, then all ways to build joins
    3425             :      * of three items (from two-item joins and single items), then four-item
    3426             :      * joins, and so on until we have considered all ways to join all the
    3427             :      * items into one rel.
    3428             :      *
    3429             :      * root->join_rel_level[j] is a list of all the j-item rels.  Initially we
    3430             :      * set root->join_rel_level[1] to represent all the single-jointree-item
    3431             :      * relations.
    3432             :      */
    3433       77208 :     root->join_rel_level = (List **) palloc0((levels_needed + 1) * sizeof(List *));
    3434             : 
    3435       77208 :     root->join_rel_level[1] = initial_rels;
    3436             : 
    3437      183788 :     for (lev = 2; lev <= levels_needed; lev++)
    3438             :     {
    3439             :         ListCell   *lc;
    3440             : 
    3441             :         /*
    3442             :          * Determine all possible pairs of relations to be joined at this
    3443             :          * level, and build paths for making each one from every available
    3444             :          * pair of lower-level relations.
    3445             :          */
    3446      106582 :         join_search_one_level(root, lev);
    3447             : 
    3448             :         /*
    3449             :          * Run generate_partitionwise_join_paths() and
    3450             :          * generate_useful_gather_paths() for each just-processed joinrel.  We
    3451             :          * could not do this earlier because both regular and partial paths
    3452             :          * can get added to a particular joinrel at multiple times within
    3453             :          * join_search_one_level.
    3454             :          *
    3455             :          * After that, we're done creating paths for the joinrel, so run
    3456             :          * set_cheapest().
    3457             :          */
    3458      269990 :         foreach(lc, root->join_rel_level[lev])
    3459             :         {
    3460      163410 :             rel = (RelOptInfo *) lfirst(lc);
    3461             : 
    3462             :             /* Create paths for partitionwise joins. */
    3463      163410 :             generate_partitionwise_join_paths(root, rel);
    3464             : 
    3465             :             /*
    3466             :              * Except for the topmost scan/join rel, consider gathering
    3467             :              * partial paths.  We'll do the same for the topmost scan/join rel
    3468             :              * once we know the final targetlist (see grouping_planner's and
    3469             :              * its call to apply_scanjoin_target_to_paths).
    3470             :              */
    3471      163410 :             if (!bms_equal(rel->relids, root->all_query_rels))
    3472       86648 :                 generate_useful_gather_paths(root, rel, false);
    3473             : 
    3474             :             /* Find and save the cheapest paths for this rel */
    3475      163410 :             set_cheapest(rel);
    3476             : 
    3477             : #ifdef OPTIMIZER_DEBUG
    3478             :             pprint(rel);
    3479             : #endif
    3480             :         }
    3481             :     }
    3482             : 
    3483             :     /*
    3484             :      * We should have a single rel at the final level.
    3485             :      */
    3486       77206 :     if (root->join_rel_level[levels_needed] == NIL)
    3487           0 :         elog(ERROR, "failed to build any %d-way joins", levels_needed);
    3488             :     Assert(list_length(root->join_rel_level[levels_needed]) == 1);
    3489             : 
    3490       77206 :     rel = (RelOptInfo *) linitial(root->join_rel_level[levels_needed]);
    3491             : 
    3492       77206 :     root->join_rel_level = NULL;
    3493             : 
    3494       77206 :     return rel;
    3495             : }
    3496             : 
    3497             : /*****************************************************************************
    3498             :  *          PUSHING QUALS DOWN INTO SUBQUERIES
    3499             :  *****************************************************************************/
    3500             : 
    3501             : /*
    3502             :  * subquery_is_pushdown_safe - is a subquery safe for pushing down quals?
    3503             :  *
    3504             :  * subquery is the particular component query being checked.  topquery
    3505             :  * is the top component of a set-operations tree (the same Query if no
    3506             :  * set-op is involved).
    3507             :  *
    3508             :  * Conditions checked here:
    3509             :  *
    3510             :  * 1. If the subquery has a LIMIT clause, we must not push down any quals,
    3511             :  * since that could change the set of rows returned.
    3512             :  *
    3513             :  * 2. If the subquery contains EXCEPT or EXCEPT ALL set ops we cannot push
    3514             :  * quals into it, because that could change the results.
    3515             :  *
    3516             :  * 3. If the subquery uses DISTINCT, we cannot push volatile quals into it.
    3517             :  * This is because upper-level quals should semantically be evaluated only
    3518             :  * once per distinct row, not once per original row, and if the qual is
    3519             :  * volatile then extra evaluations could change the results.  (This issue
    3520             :  * does not apply to other forms of aggregation such as GROUP BY, because
    3521             :  * when those are present we push into HAVING not WHERE, so that the quals
    3522             :  * are still applied after aggregation.)
    3523             :  *
    3524             :  * 4. If the subquery contains window functions, we cannot push volatile quals
    3525             :  * into it.  The issue here is a bit different from DISTINCT: a volatile qual
    3526             :  * might succeed for some rows of a window partition and fail for others,
    3527             :  * thereby changing the partition contents and thus the window functions'
    3528             :  * results for rows that remain.
    3529             :  *
    3530             :  * 5. If the subquery contains any set-returning functions in its targetlist,
    3531             :  * we cannot push volatile quals into it.  That would push them below the SRFs
    3532             :  * and thereby change the number of times they are evaluated.  Also, a
    3533             :  * volatile qual could succeed for some SRF output rows and fail for others,
    3534             :  * a behavior that cannot occur if it's evaluated before SRF expansion.
    3535             :  *
    3536             :  * 6. If the subquery has nonempty grouping sets, we cannot push down any
    3537             :  * quals.  The concern here is that a qual referencing a "constant" grouping
    3538             :  * column could get constant-folded, which would be improper because the value
    3539             :  * is potentially nullable by grouping-set expansion.  This restriction could
    3540             :  * be removed if we had a parsetree representation that shows that such
    3541             :  * grouping columns are not really constant.  (There are other ideas that
    3542             :  * could be used to relax this restriction, but that's the approach most
    3543             :  * likely to get taken in the future.  Note that there's not much to be gained
    3544             :  * so long as subquery_planner can't move HAVING clauses to WHERE within such
    3545             :  * a subquery.)
    3546             :  *
    3547             :  * In addition, we make several checks on the subquery's output columns to see
    3548             :  * if it is safe to reference them in pushed-down quals.  If output column k
    3549             :  * is found to be unsafe to reference, we set the reason for that inside
    3550             :  * safetyInfo->unsafeFlags[k], but we don't reject the subquery overall since
    3551             :  * column k might not be referenced by some/all quals.  The unsafeFlags[]
    3552             :  * array will be consulted later by qual_is_pushdown_safe().  It's better to
    3553             :  * do it this way than to make the checks directly in qual_is_pushdown_safe(),
    3554             :  * because when the subquery involves set operations we have to check the
    3555             :  * output expressions in each arm of the set op.
    3556             :  *
    3557             :  * Note: pushing quals into a DISTINCT subquery is theoretically dubious:
    3558             :  * we're effectively assuming that the quals cannot distinguish values that
    3559             :  * the DISTINCT's equality operator sees as equal, yet there are many
    3560             :  * counterexamples to that assumption.  However use of such a qual with a
    3561             :  * DISTINCT subquery would be unsafe anyway, since there's no guarantee which
    3562             :  * "equal" value will be chosen as the output value by the DISTINCT operation.
    3563             :  * So we don't worry too much about that.  Another objection is that if the
    3564             :  * qual is expensive to evaluate, running it for each original row might cost
    3565             :  * more than we save by eliminating rows before the DISTINCT step.  But it
    3566             :  * would be very hard to estimate that at this stage, and in practice pushdown
    3567             :  * seldom seems to make things worse, so we ignore that problem too.
    3568             :  *
    3569             :  * Note: likewise, pushing quals into a subquery with window functions is a
    3570             :  * bit dubious: the quals might remove some rows of a window partition while
    3571             :  * leaving others, causing changes in the window functions' results for the
    3572             :  * surviving rows.  We insist that such a qual reference only partitioning
    3573             :  * columns, but again that only protects us if the qual does not distinguish
    3574             :  * values that the partitioning equality operator sees as equal.  The risks
    3575             :  * here are perhaps larger than for DISTINCT, since no de-duplication of rows
    3576             :  * occurs and thus there is no theoretical problem with such a qual.  But
    3577             :  * we'll do this anyway because the potential performance benefits are very
    3578             :  * large, and we've seen no field complaints about the longstanding comparable
    3579             :  * behavior with DISTINCT.
    3580             :  */
    3581             : static bool
    3582        1498 : subquery_is_pushdown_safe(Query *subquery, Query *topquery,
    3583             :                           pushdown_safety_info *safetyInfo)
    3584             : {
    3585             :     SetOperationStmt *topop;
    3586             : 
    3587             :     /* Check point 1 */
    3588        1498 :     if (subquery->limitOffset != NULL || subquery->limitCount != NULL)
    3589         128 :         return false;
    3590             : 
    3591             :     /* Check point 6 */
    3592        1370 :     if (subquery->groupClause && subquery->groupingSets)
    3593          12 :         return false;
    3594             : 
    3595             :     /* Check points 3, 4, and 5 */
    3596        1358 :     if (subquery->distinctClause ||
    3597        1286 :         subquery->hasWindowFuncs ||
    3598        1022 :         subquery->hasTargetSRFs)
    3599         526 :         safetyInfo->unsafeVolatile = true;
    3600             : 
    3601             :     /*
    3602             :      * If we're at a leaf query, check for unsafe expressions in its target
    3603             :      * list, and mark any reasons why they're unsafe in unsafeFlags[].
    3604             :      * (Non-leaf nodes in setop trees have only simple Vars in their tlists,
    3605             :      * so no need to check them.)
    3606             :      */
    3607        1358 :     if (subquery->setOperations == NULL)
    3608        1278 :         check_output_expressions(subquery, safetyInfo);
    3609             : 
    3610             :     /* Are we at top level, or looking at a setop component? */
    3611        1358 :     if (subquery == topquery)
    3612             :     {
    3613             :         /* Top level, so check any component queries */
    3614        1192 :         if (subquery->setOperations != NULL)
    3615          80 :             if (!recurse_pushdown_safe(subquery->setOperations, topquery,
    3616             :                                        safetyInfo))
    3617           0 :                 return false;
    3618             :     }
    3619             :     else
    3620             :     {
    3621             :         /* Setop component must not have more components (too weird) */
    3622         166 :         if (subquery->setOperations != NULL)
    3623           0 :             return false;
    3624             :         /* Check whether setop component output types match top level */
    3625         166 :         topop = castNode(SetOperationStmt, topquery->setOperations);
    3626             :         Assert(topop);
    3627         166 :         compare_tlist_datatypes(subquery->targetList,
    3628             :                                 topop->colTypes,
    3629             :                                 safetyInfo);
    3630             :     }
    3631        1358 :     return true;
    3632             : }
    3633             : 
    3634             : /*
    3635             :  * Helper routine to recurse through setOperations tree
    3636             :  */
    3637             : static bool
    3638         252 : recurse_pushdown_safe(Node *setOp, Query *topquery,
    3639             :                       pushdown_safety_info *safetyInfo)
    3640             : {
    3641         252 :     if (IsA(setOp, RangeTblRef))
    3642             :     {
    3643         166 :         RangeTblRef *rtr = (RangeTblRef *) setOp;
    3644         166 :         RangeTblEntry *rte = rt_fetch(rtr->rtindex, topquery->rtable);
    3645         166 :         Query      *subquery = rte->subquery;
    3646             : 
    3647             :         Assert(subquery != NULL);
    3648         166 :         return subquery_is_pushdown_safe(subquery, topquery, safetyInfo);
    3649             :     }
    3650          86 :     else if (IsA(setOp, SetOperationStmt))
    3651             :     {
    3652          86 :         SetOperationStmt *op = (SetOperationStmt *) setOp;
    3653             : 
    3654             :         /* EXCEPT is no good (point 2 for subquery_is_pushdown_safe) */
    3655          86 :         if (op->op == SETOP_EXCEPT)
    3656           0 :             return false;
    3657             :         /* Else recurse */
    3658          86 :         if (!recurse_pushdown_safe(op->larg, topquery, safetyInfo))
    3659           0 :             return false;
    3660          86 :         if (!recurse_pushdown_safe(op->rarg, topquery, safetyInfo))
    3661           0 :             return false;
    3662             :     }
    3663             :     else
    3664             :     {
    3665           0 :         elog(ERROR, "unrecognized node type: %d",
    3666             :              (int) nodeTag(setOp));
    3667             :     }
    3668          86 :     return true;
    3669             : }
    3670             : 
    3671             : /*
    3672             :  * check_output_expressions - check subquery's output expressions for safety
    3673             :  *
    3674             :  * There are several cases in which it's unsafe to push down an upper-level
    3675             :  * qual if it references a particular output column of a subquery.  We check
    3676             :  * each output column of the subquery and set flags in unsafeFlags[k] when we
    3677             :  * see that column is unsafe for a pushed-down qual to reference.  The
    3678             :  * conditions checked here are:
    3679             :  *
    3680             :  * 1. We must not push down any quals that refer to subselect outputs that
    3681             :  * return sets, else we'd introduce functions-returning-sets into the
    3682             :  * subquery's WHERE/HAVING quals.
    3683             :  *
    3684             :  * 2. We must not push down any quals that refer to subselect outputs that
    3685             :  * contain volatile functions, for fear of introducing strange results due
    3686             :  * to multiple evaluation of a volatile function.
    3687             :  *
    3688             :  * 3. If the subquery uses DISTINCT ON, we must not push down any quals that
    3689             :  * refer to non-DISTINCT output columns, because that could change the set
    3690             :  * of rows returned.  (This condition is vacuous for DISTINCT, because then
    3691             :  * there are no non-DISTINCT output columns, so we needn't check.  Note that
    3692             :  * subquery_is_pushdown_safe already reported that we can't use volatile
    3693             :  * quals if there's DISTINCT or DISTINCT ON.)
    3694             :  *
    3695             :  * 4. If the subquery has any window functions, we must not push down quals
    3696             :  * that reference any output columns that are not listed in all the subquery's
    3697             :  * window PARTITION BY clauses.  We can push down quals that use only
    3698             :  * partitioning columns because they should succeed or fail identically for
    3699             :  * every row of any one window partition, and totally excluding some
    3700             :  * partitions will not change a window function's results for remaining
    3701             :  * partitions.  (Again, this also requires nonvolatile quals, but
    3702             :  * subquery_is_pushdown_safe handles that.).  Subquery columns marked as
    3703             :  * unsafe for this reason can still have WindowClause run conditions pushed
    3704             :  * down.
    3705             :  */
    3706             : static void
    3707        1278 : check_output_expressions(Query *subquery, pushdown_safety_info *safetyInfo)
    3708             : {
    3709             :     ListCell   *lc;
    3710             : 
    3711        9058 :     foreach(lc, subquery->targetList)
    3712             :     {
    3713        7780 :         TargetEntry *tle = (TargetEntry *) lfirst(lc);
    3714             : 
    3715        7780 :         if (tle->resjunk)
    3716         144 :             continue;           /* ignore resjunk columns */
    3717             : 
    3718             :         /* Functions returning sets are unsafe (point 1) */
    3719        7636 :         if (subquery->hasTargetSRFs &&
    3720         614 :             (safetyInfo->unsafeFlags[tle->resno] &
    3721         614 :              UNSAFE_HAS_SET_FUNC) == 0 &&
    3722         614 :             expression_returns_set((Node *) tle->expr))
    3723             :         {
    3724         352 :             safetyInfo->unsafeFlags[tle->resno] |= UNSAFE_HAS_SET_FUNC;
    3725         352 :             continue;
    3726             :         }
    3727             : 
    3728             :         /* Volatile functions are unsafe (point 2) */
    3729        7284 :         if ((safetyInfo->unsafeFlags[tle->resno] &
    3730        7272 :              UNSAFE_HAS_VOLATILE_FUNC) == 0 &&
    3731        7272 :             contain_volatile_functions((Node *) tle->expr))
    3732             :         {
    3733          78 :             safetyInfo->unsafeFlags[tle->resno] |= UNSAFE_HAS_VOLATILE_FUNC;
    3734          78 :             continue;
    3735             :         }
    3736             : 
    3737             :         /* If subquery uses DISTINCT ON, check point 3 */
    3738        7206 :         if (subquery->hasDistinctOn &&
    3739           0 :             (safetyInfo->unsafeFlags[tle->resno] &
    3740           0 :              UNSAFE_NOTIN_DISTINCTON_CLAUSE) == 0 &&
    3741           0 :             !targetIsInSortList(tle, InvalidOid, subquery->distinctClause))
    3742             :         {
    3743             :             /* non-DISTINCT column, so mark it unsafe */
    3744           0 :             safetyInfo->unsafeFlags[tle->resno] |= UNSAFE_NOTIN_DISTINCTON_CLAUSE;
    3745           0 :             continue;
    3746             :         }
    3747             : 
    3748             :         /* If subquery uses window functions, check point 4 */
    3749        7206 :         if (subquery->hasWindowFuncs &&
    3750        1146 :             (safetyInfo->unsafeFlags[tle->resno] &
    3751        1146 :              UNSAFE_NOTIN_DISTINCTON_CLAUSE) == 0 &&
    3752        1146 :             !targetIsInAllPartitionLists(tle, subquery))
    3753             :         {
    3754             :             /* not present in all PARTITION BY clauses, so mark it unsafe */
    3755        1050 :             safetyInfo->unsafeFlags[tle->resno] |= UNSAFE_NOTIN_PARTITIONBY_CLAUSE;
    3756        1050 :             continue;
    3757             :         }
    3758             :     }
    3759        1278 : }
    3760             : 
    3761             : /*
    3762             :  * For subqueries using UNION/UNION ALL/INTERSECT/INTERSECT ALL, we can
    3763             :  * push quals into each component query, but the quals can only reference
    3764             :  * subquery columns that suffer no type coercions in the set operation.
    3765             :  * Otherwise there are possible semantic gotchas.  So, we check the
    3766             :  * component queries to see if any of them have output types different from
    3767             :  * the top-level setop outputs.  We set the UNSAFE_TYPE_MISMATCH bit in
    3768             :  * unsafeFlags[k] if column k has different type in any component.
    3769             :  *
    3770             :  * We don't have to care about typmods here: the only allowed difference
    3771             :  * between set-op input and output typmods is input is a specific typmod
    3772             :  * and output is -1, and that does not require a coercion.
    3773             :  *
    3774             :  * tlist is a subquery tlist.
    3775             :  * colTypes is an OID list of the top-level setop's output column types.
    3776             :  * safetyInfo is the pushdown_safety_info to set unsafeFlags[] for.
    3777             :  */
    3778             : static void
    3779         166 : compare_tlist_datatypes(List *tlist, List *colTypes,
    3780             :                         pushdown_safety_info *safetyInfo)
    3781             : {
    3782             :     ListCell   *l;
    3783         166 :     ListCell   *colType = list_head(colTypes);
    3784             : 
    3785         570 :     foreach(l, tlist)
    3786             :     {
    3787         404 :         TargetEntry *tle = (TargetEntry *) lfirst(l);
    3788             : 
    3789         404 :         if (tle->resjunk)
    3790           0 :             continue;           /* ignore resjunk columns */
    3791         404 :         if (colType == NULL)
    3792           0 :             elog(ERROR, "wrong number of tlist entries");
    3793         404 :         if (exprType((Node *) tle->expr) != lfirst_oid(colType))
    3794          28 :             safetyInfo->unsafeFlags[tle->resno] |= UNSAFE_TYPE_MISMATCH;
    3795         404 :         colType = lnext(colTypes, colType);
    3796             :     }
    3797         166 :     if (colType != NULL)
    3798           0 :         elog(ERROR, "wrong number of tlist entries");
    3799         166 : }
    3800             : 
    3801             : /*
    3802             :  * targetIsInAllPartitionLists
    3803             :  *      True if the TargetEntry is listed in the PARTITION BY clause
    3804             :  *      of every window defined in the query.
    3805             :  *
    3806             :  * It would be safe to ignore windows not actually used by any window
    3807             :  * function, but it's not easy to get that info at this stage; and it's
    3808             :  * unlikely to be useful to spend any extra cycles getting it, since
    3809             :  * unreferenced window definitions are probably infrequent in practice.
    3810             :  */
    3811             : static bool
    3812        1146 : targetIsInAllPartitionLists(TargetEntry *tle, Query *query)
    3813             : {
    3814             :     ListCell   *lc;
    3815             : 
    3816        1266 :     foreach(lc, query->windowClause)
    3817             :     {
    3818        1170 :         WindowClause *wc = (WindowClause *) lfirst(lc);
    3819             : 
    3820        1170 :         if (!targetIsInSortList(tle, InvalidOid, wc->partitionClause))
    3821        1050 :             return false;
    3822             :     }
    3823          96 :     return true;
    3824             : }
    3825             : 
    3826             : /*
    3827             :  * qual_is_pushdown_safe - is a particular rinfo safe to push down?
    3828             :  *
    3829             :  * rinfo is a restriction clause applying to the given subquery (whose RTE
    3830             :  * has index rti in the parent query).
    3831             :  *
    3832             :  * Conditions checked here:
    3833             :  *
    3834             :  * 1. rinfo's clause must not contain any SubPlans (mainly because it's
    3835             :  * unclear that it will work correctly: SubLinks will already have been
    3836             :  * transformed into SubPlans in the qual, but not in the subquery).  Note that
    3837             :  * SubLinks that transform to initplans are safe, and will be accepted here
    3838             :  * because what we'll see in the qual is just a Param referencing the initplan
    3839             :  * output.
    3840             :  *
    3841             :  * 2. If unsafeVolatile is set, rinfo's clause must not contain any volatile
    3842             :  * functions.
    3843             :  *
    3844             :  * 3. If unsafeLeaky is set, rinfo's clause must not contain any leaky
    3845             :  * functions that are passed Var nodes, and therefore might reveal values from
    3846             :  * the subquery as side effects.
    3847             :  *
    3848             :  * 4. rinfo's clause must not refer to the whole-row output of the subquery
    3849             :  * (since there is no easy way to name that within the subquery itself).
    3850             :  *
    3851             :  * 5. rinfo's clause must not refer to any subquery output columns that were
    3852             :  * found to be unsafe to reference by subquery_is_pushdown_safe().
    3853             :  */
    3854             : static pushdown_safe_type
    3855        1564 : qual_is_pushdown_safe(Query *subquery, Index rti, RestrictInfo *rinfo,
    3856             :                       pushdown_safety_info *safetyInfo)
    3857             : {
    3858        1564 :     pushdown_safe_type safe = PUSHDOWN_SAFE;
    3859        1564 :     Node       *qual = (Node *) rinfo->clause;
    3860             :     List       *vars;
    3861             :     ListCell   *vl;
    3862             : 
    3863             :     /* Refuse subselects (point 1) */
    3864        1564 :     if (contain_subplans(qual))
    3865          66 :         return PUSHDOWN_UNSAFE;
    3866             : 
    3867             :     /* Refuse volatile quals if we found they'd be unsafe (point 2) */
    3868        2124 :     if (safetyInfo->unsafeVolatile &&
    3869         626 :         contain_volatile_functions((Node *) rinfo))
    3870          18 :         return PUSHDOWN_UNSAFE;
    3871             : 
    3872             :     /* Refuse leaky quals if told to (point 3) */
    3873        1786 :     if (safetyInfo->unsafeLeaky &&
    3874         306 :         contain_leaked_vars(qual))
    3875         138 :         return PUSHDOWN_UNSAFE;
    3876             : 
    3877             :     /*
    3878             :      * Examine all Vars used in clause.  Since it's a restriction clause, all
    3879             :      * such Vars must refer to subselect output columns ... unless this is
    3880             :      * part of a LATERAL subquery, in which case there could be lateral
    3881             :      * references.
    3882             :      *
    3883             :      * By omitting the relevant flags, this also gives us a cheap sanity check
    3884             :      * that no aggregates or window functions appear in the qual.  Those would
    3885             :      * be unsafe to push down, but at least for the moment we could never see
    3886             :      * any in a qual anyhow.
    3887             :      */
    3888        1342 :     vars = pull_var_clause(qual, PVC_INCLUDE_PLACEHOLDERS);
    3889        2590 :     foreach(vl, vars)
    3890             :     {
    3891        1450 :         Var        *var = (Var *) lfirst(vl);
    3892             : 
    3893             :         /*
    3894             :          * XXX Punt if we find any PlaceHolderVars in the restriction clause.
    3895             :          * It's not clear whether a PHV could safely be pushed down, and even
    3896             :          * less clear whether such a situation could arise in any cases of
    3897             :          * practical interest anyway.  So for the moment, just refuse to push
    3898             :          * down.
    3899             :          */
    3900        1450 :         if (!IsA(var, Var))
    3901             :         {
    3902           0 :             safe = PUSHDOWN_UNSAFE;
    3903           0 :             break;
    3904             :         }
    3905             : 
    3906             :         /*
    3907             :          * Punt if we find any lateral references.  It would be safe to push
    3908             :          * these down, but we'd have to convert them into outer references,
    3909             :          * which subquery_push_qual lacks the infrastructure to do.  The case
    3910             :          * arises so seldom that it doesn't seem worth working hard on.
    3911             :          */
    3912        1450 :         if (var->varno != rti)
    3913             :         {
    3914          12 :             safe = PUSHDOWN_UNSAFE;
    3915          12 :             break;
    3916             :         }
    3917             : 
    3918             :         /* Subqueries have no system columns */
    3919             :         Assert(var->varattno >= 0);
    3920             : 
    3921             :         /* Check point 4 */
    3922        1438 :         if (var->varattno == 0)
    3923             :         {
    3924           0 :             safe = PUSHDOWN_UNSAFE;
    3925           0 :             break;
    3926             :         }
    3927             : 
    3928             :         /* Check point 5 */
    3929        1438 :         if (safetyInfo->unsafeFlags[var->varattno] != 0)
    3930             :         {
    3931         514 :             if (safetyInfo->unsafeFlags[var->varattno] &
    3932             :                 (UNSAFE_HAS_VOLATILE_FUNC | UNSAFE_HAS_SET_FUNC |
    3933             :                  UNSAFE_NOTIN_DISTINCTON_CLAUSE | UNSAFE_TYPE_MISMATCH))
    3934             :             {
    3935         190 :                 safe = PUSHDOWN_UNSAFE;
    3936         190 :                 break;
    3937             :             }
    3938             :             else
    3939             :             {
    3940             :                 /* UNSAFE_NOTIN_PARTITIONBY_CLAUSE is ok for run conditions */
    3941         324 :                 safe = PUSHDOWN_WINDOWCLAUSE_RUNCOND;
    3942             :                 /* don't break, we might find another Var that's unsafe */
    3943             :             }
    3944             :         }
    3945             :     }
    3946             : 
    3947        1342 :     list_free(vars);
    3948             : 
    3949        1342 :     return safe;
    3950             : }
    3951             : 
    3952             : /*
    3953             :  * subquery_push_qual - push down a qual that we have determined is safe
    3954             :  */
    3955             : static void
    3956        1012 : subquery_push_qual(Query *subquery, RangeTblEntry *rte, Index rti, Node *qual)
    3957             : {
    3958        1012 :     if (subquery->setOperations != NULL)
    3959             :     {
    3960             :         /* Recurse to push it separately to each component query */
    3961          56 :         recurse_push_qual(subquery->setOperations, subquery,
    3962             :                           rte, rti, qual);
    3963             :     }
    3964             :     else
    3965             :     {
    3966             :         /*
    3967             :          * We need to replace Vars in the qual (which must refer to outputs of
    3968             :          * the subquery) with copies of the subquery's targetlist expressions.
    3969             :          * Note that at this point, any uplevel Vars in the qual should have
    3970             :          * been replaced with Params, so they need no work.
    3971             :          *
    3972             :          * This step also ensures that when we are pushing into a setop tree,
    3973             :          * each component query gets its own copy of the qual.
    3974             :          */
    3975         956 :         qual = ReplaceVarsFromTargetList(qual, rti, 0, rte,
    3976             :                                          subquery->targetList,
    3977             :                                          REPLACEVARS_REPORT_ERROR, 0,
    3978             :                                          &subquery->hasSubLinks);
    3979             : 
    3980             :         /*
    3981             :          * Now attach the qual to the proper place: normally WHERE, but if the
    3982             :          * subquery uses grouping or aggregation, put it in HAVING (since the
    3983             :          * qual really refers to the group-result rows).
    3984             :          */
    3985         956 :         if (subquery->hasAggs || subquery->groupClause || subquery->groupingSets || subquery->havingQual)
    3986         162 :             subquery->havingQual = make_and_qual(subquery->havingQual, qual);
    3987             :         else
    3988         794 :             subquery->jointree->quals =
    3989         794 :                 make_and_qual(subquery->jointree->quals, qual);
    3990             : 
    3991             :         /*
    3992             :          * We need not change the subquery's hasAggs or hasSubLinks flags,
    3993             :          * since we can't be pushing down any aggregates that weren't there
    3994             :          * before, and we don't push down subselects at all.
    3995             :          */
    3996             :     }
    3997        1012 : }
    3998             : 
    3999             : /*
    4000             :  * Helper routine to recurse through setOperations tree
    4001             :  */
    4002             : static void
    4003         180 : recurse_push_qual(Node *setOp, Query *topquery,
    4004             :                   RangeTblEntry *rte, Index rti, Node *qual)
    4005             : {
    4006         180 :     if (IsA(setOp, RangeTblRef))
    4007             :     {
    4008         118 :         RangeTblRef *rtr = (RangeTblRef *) setOp;
    4009         118 :         RangeTblEntry *subrte = rt_fetch(rtr->rtindex, topquery->rtable);
    4010         118 :         Query      *subquery = subrte->subquery;
    4011             : 
    4012             :         Assert(subquery != NULL);
    4013         118 :         subquery_push_qual(subquery, rte, rti, qual);
    4014             :     }
    4015          62 :     else if (IsA(setOp, SetOperationStmt))
    4016             :     {
    4017          62 :         SetOperationStmt *op = (SetOperationStmt *) setOp;
    4018             : 
    4019          62 :         recurse_push_qual(op->larg, topquery, rte, rti, qual);
    4020          62 :         recurse_push_qual(op->rarg, topquery, rte, rti, qual);
    4021             :     }
    4022             :     else
    4023             :     {
    4024           0 :         elog(ERROR, "unrecognized node type: %d",
    4025             :              (int) nodeTag(setOp));
    4026             :     }
    4027         180 : }
    4028             : 
    4029             : /*****************************************************************************
    4030             :  *          SIMPLIFYING SUBQUERY TARGETLISTS
    4031             :  *****************************************************************************/
    4032             : 
    4033             : /*
    4034             :  * remove_unused_subquery_outputs
    4035             :  *      Remove subquery targetlist items we don't need
    4036             :  *
    4037             :  * It's possible, even likely, that the upper query does not read all the
    4038             :  * output columns of the subquery.  We can remove any such outputs that are
    4039             :  * not needed by the subquery itself (e.g., as sort/group columns) and do not
    4040             :  * affect semantics otherwise (e.g., volatile functions can't be removed).
    4041             :  * This is useful not only because we might be able to remove expensive-to-
    4042             :  * compute expressions, but because deletion of output columns might allow
    4043             :  * optimizations such as join removal to occur within the subquery.
    4044             :  *
    4045             :  * extra_used_attrs can be passed as non-NULL to mark any columns (offset by
    4046             :  * FirstLowInvalidHeapAttributeNumber) that we should not remove.  This
    4047             :  * parameter is modified by the function, so callers must make a copy if they
    4048             :  * need to use the passed in Bitmapset after calling this function.
    4049             :  *
    4050             :  * To avoid affecting column numbering in the targetlist, we don't physically
    4051             :  * remove unused tlist entries, but rather replace their expressions with NULL
    4052             :  * constants.  This is implemented by modifying subquery->targetList.
    4053             :  */
    4054             : static void
    4055        7076 : remove_unused_subquery_outputs(Query *subquery, RelOptInfo *rel,
    4056             :                                Bitmapset *extra_used_attrs)
    4057             : {
    4058             :     Bitmapset  *attrs_used;
    4059             :     ListCell   *lc;
    4060             : 
    4061             :     /*
    4062             :      * Just point directly to extra_used_attrs. No need to bms_copy as none of
    4063             :      * the current callers use the Bitmapset after calling this function.
    4064             :      */
    4065        7076 :     attrs_used = extra_used_attrs;
    4066             : 
    4067             :     /*
    4068             :      * Do nothing if subquery has UNION/INTERSECT/EXCEPT: in principle we
    4069             :      * could update all the child SELECTs' tlists, but it seems not worth the
    4070             :      * trouble presently.
    4071             :      */
    4072        7076 :     if (subquery->setOperations)
    4073        1054 :         return;
    4074             : 
    4075             :     /*
    4076             :      * If subquery has regular DISTINCT (not DISTINCT ON), we're wasting our
    4077             :      * time: all its output columns must be used in the distinctClause.
    4078             :      */
    4079        6534 :     if (subquery->distinctClause && !subquery->hasDistinctOn)
    4080         238 :         return;
    4081             : 
    4082             :     /*
    4083             :      * Collect a bitmap of all the output column numbers used by the upper
    4084             :      * query.
    4085             :      *
    4086             :      * Add all the attributes needed for joins or final output.  Note: we must
    4087             :      * look at rel's targetlist, not the attr_needed data, because attr_needed
    4088             :      * isn't computed for inheritance child rels, cf set_append_rel_size().
    4089             :      * (XXX might be worth changing that sometime.)
    4090             :      */
    4091        6296 :     pull_varattnos((Node *) rel->reltarget->exprs, rel->relid, &attrs_used);
    4092             : 
    4093             :     /* Add all the attributes used by un-pushed-down restriction clauses. */
    4094        6990 :     foreach(lc, rel->baserestrictinfo)
    4095             :     {
    4096         694 :         RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
    4097             : 
    4098         694 :         pull_varattnos((Node *) rinfo->clause, rel->relid, &attrs_used);
    4099             :     }
    4100             : 
    4101             :     /*
    4102             :      * If there's a whole-row reference to the subquery, we can't remove
    4103             :      * anything.
    4104             :      */
    4105        6296 :     if (bms_is_member(0 - FirstLowInvalidHeapAttributeNumber, attrs_used))
    4106         274 :         return;
    4107             : 
    4108             :     /*
    4109             :      * Run through the tlist and zap entries we don't need.  It's okay to
    4110             :      * modify the tlist items in-place because set_subquery_pathlist made a
    4111             :      * copy of the subquery.
    4112             :      */
    4113       26760 :     foreach(lc, subquery->targetList)
    4114             :     {
    4115       20738 :         TargetEntry *tle = (TargetEntry *) lfirst(lc);
    4116       20738 :         Node       *texpr = (Node *) tle->expr;
    4117             : 
    4118             :         /*
    4119             :          * If it has a sortgroupref number, it's used in some sort/group
    4120             :          * clause so we'd better not remove it.  Also, don't remove any
    4121             :          * resjunk columns, since their reason for being has nothing to do
    4122             :          * with anybody reading the subquery's output.  (It's likely that
    4123             :          * resjunk columns in a sub-SELECT would always have ressortgroupref
    4124             :          * set, but even if they don't, it seems imprudent to remove them.)
    4125             :          */
    4126       20738 :         if (tle->ressortgroupref || tle->resjunk)
    4127        2322 :             continue;
    4128             : 
    4129             :         /*
    4130             :          * If it's used by the upper query, we can't remove it.
    4131             :          */
    4132       18416 :         if (bms_is_member(tle->resno - FirstLowInvalidHeapAttributeNumber,
    4133             :                           attrs_used))
    4134       12536 :             continue;
    4135             : 
    4136             :         /*
    4137             :          * If it contains a set-returning function, we can't remove it since
    4138             :          * that could change the number of rows returned by the subquery.
    4139             :          */
    4140        6812 :         if (subquery->hasTargetSRFs &&
    4141         932 :             expression_returns_set(texpr))
    4142         676 :             continue;
    4143             : 
    4144             :         /*
    4145             :          * If it contains volatile functions, we daren't remove it for fear
    4146             :          * that the user is expecting their side-effects to happen.
    4147             :          */
    4148        5204 :         if (contain_volatile_functions(texpr))
    4149          26 :             continue;
    4150             : 
    4151             :         /*
    4152             :          * OK, we don't need it.  Replace the expression with a NULL constant.
    4153             :          * Preserve the exposed type of the expression, in case something
    4154             :          * looks at the rowtype of the subquery's result.
    4155             :          */
    4156        5178 :         tle->expr = (Expr *) makeNullConst(exprType(texpr),
    4157             :                                            exprTypmod(texpr),
    4158             :                                            exprCollation(texpr));
    4159             :     }
    4160             : }
    4161             : 
    4162             : /*
    4163             :  * create_partial_bitmap_paths
    4164             :  *    Build partial bitmap heap path for the relation
    4165             :  */
    4166             : void
    4167      119066 : create_partial_bitmap_paths(PlannerInfo *root, RelOptInfo *rel,
    4168             :                             Path *bitmapqual)
    4169             : {
    4170             :     int         parallel_workers;
    4171             :     double      pages_fetched;
    4172             : 
    4173             :     /* Compute heap pages for bitmap heap scan */
    4174      119066 :     pages_fetched = compute_bitmap_pages(root, rel, bitmapqual, 1.0,
    4175             :                                          NULL, NULL);
    4176             : 
    4177      119066 :     parallel_workers = compute_parallel_worker(rel, pages_fetched, -1,
    4178             :                                                max_parallel_workers_per_gather);
    4179             : 
    4180      119066 :     if (parallel_workers <= 0)
    4181      114856 :         return;
    4182             : 
    4183        4210 :     add_partial_path(rel, (Path *) create_bitmap_heap_path(root, rel,
    4184             :                                                            bitmapqual, rel->lateral_relids, 1.0, parallel_workers));
    4185             : }
    4186             : 
    4187             : /*
    4188             :  * Compute the number of parallel workers that should be used to scan a
    4189             :  * relation.  We compute the parallel workers based on the size of the heap to
    4190             :  * be scanned and the size of the index to be scanned, then choose a minimum
    4191             :  * of those.
    4192             :  *
    4193             :  * "heap_pages" is the number of pages from the table that we expect to scan, or
    4194             :  * -1 if we don't expect to scan any.
    4195             :  *
    4196             :  * "index_pages" is the number of pages from the index that we expect to scan, or
    4197             :  * -1 if we don't expect to scan any.
    4198             :  *
    4199             :  * "max_workers" is caller's limit on the number of workers.  This typically
    4200             :  * comes from a GUC.
    4201             :  */
    4202             : int
    4203      602180 : compute_parallel_worker(RelOptInfo *rel, double heap_pages, double index_pages,
    4204             :                         int max_workers)
    4205             : {
    4206      602180 :     int         parallel_workers = 0;
    4207             : 
    4208             :     /*
    4209             :      * If the user has set the parallel_workers reloption, use that; otherwise
    4210             :      * select a default number of workers.
    4211             :      */
    4212      602180 :     if (rel->rel_parallel_workers != -1)
    4213        1890 :         parallel_workers = rel->rel_parallel_workers;
    4214             :     else
    4215             :     {
    4216             :         /*
    4217             :          * If the number of pages being scanned is insufficient to justify a
    4218             :          * parallel scan, just return zero ... unless it's an inheritance
    4219             :          * child. In that case, we want to generate a parallel path here
    4220             :          * anyway.  It might not be worthwhile just for this relation, but
    4221             :          * when combined with all of its inheritance siblings it may well pay
    4222             :          * off.
    4223             :          */
    4224      600290 :         if (rel->reloptkind == RELOPT_BASEREL &&
    4225      562142 :             ((heap_pages >= 0 && heap_pages < min_parallel_table_scan_size) ||
    4226       17942 :              (index_pages >= 0 && index_pages < min_parallel_index_scan_size)))
    4227      561472 :             return 0;
    4228             : 
    4229       38818 :         if (heap_pages >= 0)
    4230             :         {
    4231             :             int         heap_parallel_threshold;
    4232       36820 :             int         heap_parallel_workers = 1;
    4233             : 
    4234             :             /*
    4235             :              * Select the number of workers based on the log of the size of
    4236             :              * the relation.  This probably needs to be a good deal more
    4237             :              * sophisticated, but we need something here for now.  Note that
    4238             :              * the upper limit of the min_parallel_table_scan_size GUC is
    4239             :              * chosen to prevent overflow here.
    4240             :              */
    4241       36820 :             heap_parallel_threshold = Max(min_parallel_table_scan_size, 1);
    4242       41652 :             while (heap_pages >= (BlockNumber) (heap_parallel_threshold * 3))
    4243             :             {
    4244        4832 :                 heap_parallel_workers++;
    4245        4832 :                 heap_parallel_threshold *= 3;
    4246        4832 :                 if (heap_parallel_threshold > INT_MAX / 3)
    4247           0 :                     break;      /* avoid overflow */
    4248             :             }
    4249             : 
    4250       36820 :             parallel_workers = heap_parallel_workers;
    4251             :         }
    4252             : 
    4253       38818 :         if (index_pages >= 0)
    4254             :         {
    4255        9546 :             int         index_parallel_workers = 1;
    4256             :             int         index_parallel_threshold;
    4257             : 
    4258             :             /* same calculation as for heap_pages above */
    4259        9546 :             index_parallel_threshold = Max(min_parallel_index_scan_size, 1);
    4260        9822 :             while (index_pages >= (BlockNumber) (index_parallel_threshold * 3))
    4261             :             {
    4262         276 :                 index_parallel_workers++;
    4263         276 :                 index_parallel_threshold *= 3;
    4264         276 :                 if (index_parallel_threshold > INT_MAX / 3)
    4265           0 :                     break;      /* avoid overflow */
    4266             :             }
    4267             : 
    4268        9546 :             if (parallel_workers > 0)
    4269        7548 :                 parallel_workers = Min(parallel_workers, index_parallel_workers);
    4270             :             else
    4271        1998 :                 parallel_workers = index_parallel_workers;
    4272             :         }
    4273             :     }
    4274             : 
    4275             :     /* In no case use more than caller supplied maximum number of workers */
    4276       40708 :     parallel_workers = Min(parallel_workers, max_workers);
    4277             : 
    4278       40708 :     return parallel_workers;
    4279             : }
    4280             : 
    4281             : /*
    4282             :  * generate_partitionwise_join_paths
    4283             :  *      Create paths representing partitionwise join for given partitioned
    4284             :  *      join relation.
    4285             :  *
    4286             :  * This must not be called until after we are done adding paths for all
    4287             :  * child-joins. Otherwise, add_path might delete a path to which some path
    4288             :  * generated here has a reference.
    4289             :  */
    4290             : void
    4291      171004 : generate_partitionwise_join_paths(PlannerInfo *root, RelOptInfo *rel)
    4292             : {
    4293      171004 :     List       *live_children = NIL;
    4294             :     int         cnt_parts;
    4295             :     int         num_parts;
    4296             :     RelOptInfo **part_rels;
    4297             : 
    4298             :     /* Handle only join relations here. */
    4299      171004 :     if (!IS_JOIN_REL(rel))
    4300           0 :         return;
    4301             : 
    4302             :     /* We've nothing to do if the relation is not partitioned. */
    4303      171004 :     if (!IS_PARTITIONED_REL(rel))
    4304      169348 :         return;
    4305             : 
    4306             :     /* The relation should have consider_partitionwise_join set. */
    4307             :     Assert(rel->consider_partitionwise_join);
    4308             : 
    4309             :     /* Guard against stack overflow due to overly deep partition hierarchy. */
    4310        1656 :     check_stack_depth();
    4311             : 
    4312        1656 :     num_parts = rel->nparts;
    4313        1656 :     part_rels = rel->part_rels;
    4314             : 
    4315             :     /* Collect non-dummy child-joins. */
    4316        6206 :     for (cnt_parts = 0; cnt_parts < num_parts; cnt_parts++)
    4317             :     {
    4318        4550 :         RelOptInfo *child_rel = part_rels[cnt_parts];
    4319             : 
    4320             :         /* If it's been pruned entirely, it's certainly dummy. */
    4321        4550 :         if (child_rel == NULL)
    4322          52 :             continue;
    4323             : 
    4324             :         /* Make partitionwise join paths for this partitioned child-join. */
    4325        4498 :         generate_partitionwise_join_paths(root, child_rel);
    4326             : 
    4327             :         /* If we failed to make any path for this child, we must give up. */
    4328        4498 :         if (child_rel->pathlist == NIL)
    4329             :         {
    4330             :             /*
    4331             :              * Mark the parent joinrel as unpartitioned so that later
    4332             :              * functions treat it correctly.
    4333             :              */
    4334           0 :             rel->nparts = 0;
    4335           0 :             return;
    4336             :         }
    4337             : 
    4338             :         /* Else, identify the cheapest path for it. */
    4339        4498 :         set_cheapest(child_rel);
    4340             : 
    4341             :         /* Dummy children need not be scanned, so ignore those. */
    4342        4498 :         if (IS_DUMMY_REL(child_rel))
    4343           0 :             continue;
    4344             : 
    4345             : #ifdef OPTIMIZER_DEBUG
    4346             :         pprint(child_rel);
    4347             : #endif
    4348             : 
    4349        4498 :         live_children = lappend(live_children, child_rel);
    4350             :     }
    4351             : 
    4352             :     /* If all child-joins are dummy, parent join is also dummy. */
    4353        1656 :     if (!live_children)
    4354             :     {
    4355           0 :         mark_dummy_rel(rel);
    4356           0 :         return;
    4357             :     }
    4358             : 
    4359             :     /* Build additional paths for this rel from child-join paths. */
    4360        1656 :     add_paths_to_append_rel(root, rel, live_children);
    4361        1656 :     list_free(live_children);
    4362             : }

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