LCOV - code coverage report
Current view: top level - src/backend/optimizer/path - joinrels.c (source / functions) Hit Total Coverage
Test: PostgreSQL 12beta2 Lines: 450 479 93.9 %
Date: 2019-06-18 07:06:57 Functions: 17 17 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * joinrels.c
       4             :  *    Routines to determine which relations should be joined
       5             :  *
       6             :  * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
       7             :  * Portions Copyright (c) 1994, Regents of the University of California
       8             :  *
       9             :  *
      10             :  * IDENTIFICATION
      11             :  *    src/backend/optimizer/path/joinrels.c
      12             :  *
      13             :  *-------------------------------------------------------------------------
      14             :  */
      15             : #include "postgres.h"
      16             : 
      17             : #include "miscadmin.h"
      18             : #include "optimizer/appendinfo.h"
      19             : #include "optimizer/joininfo.h"
      20             : #include "optimizer/pathnode.h"
      21             : #include "optimizer/paths.h"
      22             : #include "partitioning/partbounds.h"
      23             : #include "utils/lsyscache.h"
      24             : #include "utils/memutils.h"
      25             : 
      26             : 
      27             : static void make_rels_by_clause_joins(PlannerInfo *root,
      28             :                                       RelOptInfo *old_rel,
      29             :                                       ListCell *other_rels);
      30             : static void make_rels_by_clauseless_joins(PlannerInfo *root,
      31             :                                           RelOptInfo *old_rel,
      32             :                                           ListCell *other_rels);
      33             : static bool has_join_restriction(PlannerInfo *root, RelOptInfo *rel);
      34             : static bool has_legal_joinclause(PlannerInfo *root, RelOptInfo *rel);
      35             : static bool restriction_is_constant_false(List *restrictlist,
      36             :                                           RelOptInfo *joinrel,
      37             :                                           bool only_pushed_down);
      38             : static void populate_joinrel_with_paths(PlannerInfo *root, RelOptInfo *rel1,
      39             :                                         RelOptInfo *rel2, RelOptInfo *joinrel,
      40             :                                         SpecialJoinInfo *sjinfo, List *restrictlist);
      41             : static void try_partitionwise_join(PlannerInfo *root, RelOptInfo *rel1,
      42             :                                    RelOptInfo *rel2, RelOptInfo *joinrel,
      43             :                                    SpecialJoinInfo *parent_sjinfo,
      44             :                                    List *parent_restrictlist);
      45             : static SpecialJoinInfo *build_child_join_sjinfo(PlannerInfo *root,
      46             :                                                 SpecialJoinInfo *parent_sjinfo,
      47             :                                                 Relids left_relids, Relids right_relids);
      48             : static int  match_expr_to_partition_keys(Expr *expr, RelOptInfo *rel,
      49             :                                          bool strict_op);
      50             : 
      51             : 
      52             : /*
      53             :  * join_search_one_level
      54             :  *    Consider ways to produce join relations containing exactly 'level'
      55             :  *    jointree items.  (This is one step of the dynamic-programming method
      56             :  *    embodied in standard_join_search.)  Join rel nodes for each feasible
      57             :  *    combination of lower-level rels are created and returned in a list.
      58             :  *    Implementation paths are created for each such joinrel, too.
      59             :  *
      60             :  * level: level of rels we want to make this time
      61             :  * root->join_rel_level[j], 1 <= j < level, is a list of rels containing j items
      62             :  *
      63             :  * The result is returned in root->join_rel_level[level].
      64             :  */
      65             : void
      66       59636 : join_search_one_level(PlannerInfo *root, int level)
      67             : {
      68       59636 :     List      **joinrels = root->join_rel_level;
      69             :     ListCell   *r;
      70             :     int         k;
      71             : 
      72             :     Assert(joinrels[level] == NIL);
      73             : 
      74             :     /* Set join_cur_level so that new joinrels are added to proper list */
      75       59636 :     root->join_cur_level = level;
      76             : 
      77             :     /*
      78             :      * First, consider left-sided and right-sided plans, in which rels of
      79             :      * exactly level-1 member relations are joined against initial relations.
      80             :      * We prefer to join using join clauses, but if we find a rel of level-1
      81             :      * members that has no join clauses, we will generate Cartesian-product
      82             :      * joins against all initial rels not already contained in it.
      83             :      */
      84      210274 :     foreach(r, joinrels[level - 1])
      85             :     {
      86      150638 :         RelOptInfo *old_rel = (RelOptInfo *) lfirst(r);
      87             : 
      88      156528 :         if (old_rel->joininfo != NIL || old_rel->has_eclass_joins ||
      89        5890 :             has_join_restriction(root, old_rel))
      90      146316 :         {
      91             :             /*
      92             :              * There are join clauses or join order restrictions relevant to
      93             :              * this rel, so consider joins between this rel and (only) those
      94             :              * initial rels it is linked to by a clause or restriction.
      95             :              *
      96             :              * At level 2 this condition is symmetric, so there is no need to
      97             :              * look at initial rels before this one in the list; we already
      98             :              * considered such joins when we were at the earlier rel.  (The
      99             :              * mirror-image joins are handled automatically by make_join_rel.)
     100             :              * In later passes (level > 2), we join rels of the previous level
     101             :              * to each initial rel they don't already include but have a join
     102             :              * clause or restriction with.
     103             :              */
     104             :             ListCell   *other_rels;
     105             : 
     106      146316 :             if (level == 2)     /* consider remaining initial rels */
     107      102238 :                 other_rels = lnext(r);
     108             :             else                /* consider all initial rels */
     109       44078 :                 other_rels = list_head(joinrels[1]);
     110             : 
     111      146316 :             make_rels_by_clause_joins(root,
     112             :                                       old_rel,
     113             :                                       other_rels);
     114             :         }
     115             :         else
     116             :         {
     117             :             /*
     118             :              * Oops, we have a relation that is not joined to any other
     119             :              * relation, either directly or by join-order restrictions.
     120             :              * Cartesian product time.
     121             :              *
     122             :              * We consider a cartesian product with each not-already-included
     123             :              * initial rel, whether it has other join clauses or not.  At
     124             :              * level 2, if there are two or more clauseless initial rels, we
     125             :              * will redundantly consider joining them in both directions; but
     126             :              * such cases aren't common enough to justify adding complexity to
     127             :              * avoid the duplicated effort.
     128             :              */
     129        4322 :             make_rels_by_clauseless_joins(root,
     130             :                                           old_rel,
     131        4322 :                                           list_head(joinrels[1]));
     132             :         }
     133             :     }
     134             : 
     135             :     /*
     136             :      * Now, consider "bushy plans" in which relations of k initial rels are
     137             :      * joined to relations of level-k initial rels, for 2 <= k <= level-2.
     138             :      *
     139             :      * We only consider bushy-plan joins for pairs of rels where there is a
     140             :      * suitable join clause (or join order restriction), in order to avoid
     141             :      * unreasonable growth of planning time.
     142             :      */
     143       65878 :     for (k = 2;; k++)
     144        6242 :     {
     145       65878 :         int         other_level = level - k;
     146             : 
     147             :         /*
     148             :          * Since make_join_rel(x, y) handles both x,y and y,x cases, we only
     149             :          * need to go as far as the halfway point.
     150             :          */
     151       65878 :         if (k > other_level)
     152       59636 :             break;
     153             : 
     154       31160 :         foreach(r, joinrels[k])
     155             :         {
     156       24918 :             RelOptInfo *old_rel = (RelOptInfo *) lfirst(r);
     157             :             ListCell   *other_rels;
     158             :             ListCell   *r2;
     159             : 
     160             :             /*
     161             :              * We can ignore relations without join clauses here, unless they
     162             :              * participate in join-order restrictions --- then we might have
     163             :              * to force a bushy join plan.
     164             :              */
     165       25002 :             if (old_rel->joininfo == NIL && !old_rel->has_eclass_joins &&
     166          84 :                 !has_join_restriction(root, old_rel))
     167          44 :                 continue;
     168             : 
     169       24874 :             if (k == other_level)
     170       14726 :                 other_rels = lnext(r);  /* only consider remaining rels */
     171             :             else
     172       10148 :                 other_rels = list_head(joinrels[other_level]);
     173             : 
     174      108272 :             for_each_cell(r2, other_rels)
     175             :             {
     176       83398 :                 RelOptInfo *new_rel = (RelOptInfo *) lfirst(r2);
     177             : 
     178       83398 :                 if (!bms_overlap(old_rel->relids, new_rel->relids))
     179             :                 {
     180             :                     /*
     181             :                      * OK, we can build a rel of the right level from this
     182             :                      * pair of rels.  Do so if there is at least one relevant
     183             :                      * join clause or join order restriction.
     184             :                      */
     185        7482 :                     if (have_relevant_joinclause(root, old_rel, new_rel) ||
     186         616 :                         have_join_order_restriction(root, old_rel, new_rel))
     187             :                     {
     188        6266 :                         (void) make_join_rel(root, old_rel, new_rel);
     189             :                     }
     190             :                 }
     191             :             }
     192             :         }
     193             :     }
     194             : 
     195             :     /*----------
     196             :      * Last-ditch effort: if we failed to find any usable joins so far, force
     197             :      * a set of cartesian-product joins to be generated.  This handles the
     198             :      * special case where all the available rels have join clauses but we
     199             :      * cannot use any of those clauses yet.  This can only happen when we are
     200             :      * considering a join sub-problem (a sub-joinlist) and all the rels in the
     201             :      * sub-problem have only join clauses with rels outside the sub-problem.
     202             :      * An example is
     203             :      *
     204             :      *      SELECT ... FROM a INNER JOIN b ON TRUE, c, d, ...
     205             :      *      WHERE a.w = c.x and b.y = d.z;
     206             :      *
     207             :      * If the "a INNER JOIN b" sub-problem does not get flattened into the
     208             :      * upper level, we must be willing to make a cartesian join of a and b;
     209             :      * but the code above will not have done so, because it thought that both
     210             :      * a and b have joinclauses.  We consider only left-sided and right-sided
     211             :      * cartesian joins in this case (no bushy).
     212             :      *----------
     213             :      */
     214       59636 :     if (joinrels[level] == NIL)
     215             :     {
     216             :         /*
     217             :          * This loop is just like the first one, except we always call
     218             :          * make_rels_by_clauseless_joins().
     219             :          */
     220          36 :         foreach(r, joinrels[level - 1])
     221             :         {
     222          24 :             RelOptInfo *old_rel = (RelOptInfo *) lfirst(r);
     223             : 
     224          24 :             make_rels_by_clauseless_joins(root,
     225             :                                           old_rel,
     226          24 :                                           list_head(joinrels[1]));
     227             :         }
     228             : 
     229             :         /*----------
     230             :          * When special joins are involved, there may be no legal way
     231             :          * to make an N-way join for some values of N.  For example consider
     232             :          *
     233             :          * SELECT ... FROM t1 WHERE
     234             :          *   x IN (SELECT ... FROM t2,t3 WHERE ...) AND
     235             :          *   y IN (SELECT ... FROM t4,t5 WHERE ...)
     236             :          *
     237             :          * We will flatten this query to a 5-way join problem, but there are
     238             :          * no 4-way joins that join_is_legal() will consider legal.  We have
     239             :          * to accept failure at level 4 and go on to discover a workable
     240             :          * bushy plan at level 5.
     241             :          *
     242             :          * However, if there are no special joins and no lateral references
     243             :          * then join_is_legal() should never fail, and so the following sanity
     244             :          * check is useful.
     245             :          *----------
     246             :          */
     247          16 :         if (joinrels[level] == NIL &&
     248           4 :             root->join_info_list == NIL &&
     249           0 :             !root->hasLateralRTEs)
     250           0 :             elog(ERROR, "failed to build any %d-way joins", level);
     251             :     }
     252       59636 : }
     253             : 
     254             : /*
     255             :  * make_rels_by_clause_joins
     256             :  *    Build joins between the given relation 'old_rel' and other relations
     257             :  *    that participate in join clauses that 'old_rel' also participates in
     258             :  *    (or participate in join-order restrictions with it).
     259             :  *    The join rels are returned in root->join_rel_level[join_cur_level].
     260             :  *
     261             :  * Note: at levels above 2 we will generate the same joined relation in
     262             :  * multiple ways --- for example (a join b) join c is the same RelOptInfo as
     263             :  * (b join c) join a, though the second case will add a different set of Paths
     264             :  * to it.  This is the reason for using the join_rel_level mechanism, which
     265             :  * automatically ensures that each new joinrel is only added to the list once.
     266             :  *
     267             :  * 'old_rel' is the relation entry for the relation to be joined
     268             :  * 'other_rels': the first cell in a linked list containing the other
     269             :  * rels to be considered for joining
     270             :  *
     271             :  * Currently, this is only used with initial rels in other_rels, but it
     272             :  * will work for joining to joinrels too.
     273             :  */
     274             : static void
     275      146316 : make_rels_by_clause_joins(PlannerInfo *root,
     276             :                           RelOptInfo *old_rel,
     277             :                           ListCell *other_rels)
     278             : {
     279             :     ListCell   *l;
     280             : 
     281      429338 :     for_each_cell(l, other_rels)
     282             :     {
     283      283022 :         RelOptInfo *other_rel = (RelOptInfo *) lfirst(l);
     284             : 
     285      444020 :         if (!bms_overlap(old_rel->relids, other_rel->relids) &&
     286      187200 :             (have_relevant_joinclause(root, old_rel, other_rel) ||
     287       26202 :              have_join_order_restriction(root, old_rel, other_rel)))
     288             :         {
     289      136104 :             (void) make_join_rel(root, old_rel, other_rel);
     290             :         }
     291             :     }
     292      146316 : }
     293             : 
     294             : /*
     295             :  * make_rels_by_clauseless_joins
     296             :  *    Given a relation 'old_rel' and a list of other relations
     297             :  *    'other_rels', create a join relation between 'old_rel' and each
     298             :  *    member of 'other_rels' that isn't already included in 'old_rel'.
     299             :  *    The join rels are returned in root->join_rel_level[join_cur_level].
     300             :  *
     301             :  * 'old_rel' is the relation entry for the relation to be joined
     302             :  * 'other_rels': the first cell of a linked list containing the
     303             :  * other rels to be considered for joining
     304             :  *
     305             :  * Currently, this is only used with initial rels in other_rels, but it would
     306             :  * work for joining to joinrels too.
     307             :  */
     308             : static void
     309        4346 : make_rels_by_clauseless_joins(PlannerInfo *root,
     310             :                               RelOptInfo *old_rel,
     311             :                               ListCell *other_rels)
     312             : {
     313             :     ListCell   *l;
     314             : 
     315       13552 :     for_each_cell(l, other_rels)
     316             :     {
     317        9206 :         RelOptInfo *other_rel = (RelOptInfo *) lfirst(l);
     318             : 
     319        9206 :         if (!bms_overlap(other_rel->relids, old_rel->relids))
     320             :         {
     321        4540 :             (void) make_join_rel(root, old_rel, other_rel);
     322             :         }
     323             :     }
     324        4346 : }
     325             : 
     326             : 
     327             : /*
     328             :  * join_is_legal
     329             :  *     Determine whether a proposed join is legal given the query's
     330             :  *     join order constraints; and if it is, determine the join type.
     331             :  *
     332             :  * Caller must supply not only the two rels, but the union of their relids.
     333             :  * (We could simplify the API by computing joinrelids locally, but this
     334             :  * would be redundant work in the normal path through make_join_rel.)
     335             :  *
     336             :  * On success, *sjinfo_p is set to NULL if this is to be a plain inner join,
     337             :  * else it's set to point to the associated SpecialJoinInfo node.  Also,
     338             :  * *reversed_p is set true if the given relations need to be swapped to
     339             :  * match the SpecialJoinInfo node.
     340             :  */
     341             : static bool
     342      150230 : join_is_legal(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
     343             :               Relids joinrelids,
     344             :               SpecialJoinInfo **sjinfo_p, bool *reversed_p)
     345             : {
     346             :     SpecialJoinInfo *match_sjinfo;
     347             :     bool        reversed;
     348             :     bool        unique_ified;
     349             :     bool        must_be_leftjoin;
     350             :     ListCell   *l;
     351             : 
     352             :     /*
     353             :      * Ensure output params are set on failure return.  This is just to
     354             :      * suppress uninitialized-variable warnings from overly anal compilers.
     355             :      */
     356      150230 :     *sjinfo_p = NULL;
     357      150230 :     *reversed_p = false;
     358             : 
     359             :     /*
     360             :      * If we have any special joins, the proposed join might be illegal; and
     361             :      * in any case we have to determine its join type.  Scan the join info
     362             :      * list for matches and conflicts.
     363             :      */
     364      150230 :     match_sjinfo = NULL;
     365      150230 :     reversed = false;
     366      150230 :     unique_ified = false;
     367      150230 :     must_be_leftjoin = false;
     368             : 
     369      342522 :     foreach(l, root->join_info_list)
     370             :     {
     371      197434 :         SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(l);
     372             : 
     373             :         /*
     374             :          * This special join is not relevant unless its RHS overlaps the
     375             :          * proposed join.  (Check this first as a fast path for dismissing
     376             :          * most irrelevant SJs quickly.)
     377             :          */
     378      197434 :         if (!bms_overlap(sjinfo->min_righthand, joinrelids))
     379       65850 :             continue;
     380             : 
     381             :         /*
     382             :          * Also, not relevant if proposed join is fully contained within RHS
     383             :          * (ie, we're still building up the RHS).
     384             :          */
     385      131584 :         if (bms_is_subset(joinrelids, sjinfo->min_righthand))
     386        2268 :             continue;
     387             : 
     388             :         /*
     389             :          * Also, not relevant if SJ is already done within either input.
     390             :          */
     391      251112 :         if (bms_is_subset(sjinfo->min_lefthand, rel1->relids) &&
     392      121796 :             bms_is_subset(sjinfo->min_righthand, rel1->relids))
     393       55060 :             continue;
     394       78946 :         if (bms_is_subset(sjinfo->min_lefthand, rel2->relids) &&
     395        4690 :             bms_is_subset(sjinfo->min_righthand, rel2->relids))
     396        1900 :             continue;
     397             : 
     398             :         /*
     399             :          * If it's a semijoin and we already joined the RHS to any other rels
     400             :          * within either input, then we must have unique-ified the RHS at that
     401             :          * point (see below).  Therefore the semijoin is no longer relevant in
     402             :          * this join path.
     403             :          */
     404       72356 :         if (sjinfo->jointype == JOIN_SEMI)
     405             :         {
     406        4026 :             if (bms_is_subset(sjinfo->syn_righthand, rel1->relids) &&
     407         672 :                 !bms_equal(sjinfo->syn_righthand, rel1->relids))
     408          12 :                 continue;
     409        4772 :             if (bms_is_subset(sjinfo->syn_righthand, rel2->relids) &&
     410        1430 :                 !bms_equal(sjinfo->syn_righthand, rel2->relids))
     411           4 :                 continue;
     412             :         }
     413             : 
     414             :         /*
     415             :          * If one input contains min_lefthand and the other contains
     416             :          * min_righthand, then we can perform the SJ at this join.
     417             :          *
     418             :          * Reject if we get matches to more than one SJ; that implies we're
     419             :          * considering something that's not really valid.
     420             :          */
     421      139072 :         if (bms_is_subset(sjinfo->min_lefthand, rel1->relids) &&
     422       66732 :             bms_is_subset(sjinfo->min_righthand, rel2->relids))
     423             :         {
     424       62736 :             if (match_sjinfo)
     425           0 :                 return false;   /* invalid join path */
     426       62736 :             match_sjinfo = sjinfo;
     427       62736 :             reversed = false;
     428             :         }
     429       12390 :         else if (bms_is_subset(sjinfo->min_lefthand, rel2->relids) &&
     430        2786 :                  bms_is_subset(sjinfo->min_righthand, rel1->relids))
     431             :         {
     432        2338 :             if (match_sjinfo)
     433           0 :                 return false;   /* invalid join path */
     434        2338 :             match_sjinfo = sjinfo;
     435        2338 :             reversed = true;
     436             :         }
     437        8950 :         else if (sjinfo->jointype == JOIN_SEMI &&
     438        1912 :                  bms_equal(sjinfo->syn_righthand, rel2->relids) &&
     439         228 :                  create_unique_path(root, rel2, rel2->cheapest_total_path,
     440             :                                     sjinfo) != NULL)
     441             :         {
     442             :             /*----------
     443             :              * For a semijoin, we can join the RHS to anything else by
     444             :              * unique-ifying the RHS (if the RHS can be unique-ified).
     445             :              * We will only get here if we have the full RHS but less
     446             :              * than min_lefthand on the LHS.
     447             :              *
     448             :              * The reason to consider such a join path is exemplified by
     449             :              *  SELECT ... FROM a,b WHERE (a.x,b.y) IN (SELECT c1,c2 FROM c)
     450             :              * If we insist on doing this as a semijoin we will first have
     451             :              * to form the cartesian product of A*B.  But if we unique-ify
     452             :              * C then the semijoin becomes a plain innerjoin and we can join
     453             :              * in any order, eg C to A and then to B.  When C is much smaller
     454             :              * than A and B this can be a huge win.  So we allow C to be
     455             :              * joined to just A or just B here, and then make_join_rel has
     456             :              * to handle the case properly.
     457             :              *
     458             :              * Note that actually we'll allow unique-ified C to be joined to
     459             :              * some other relation D here, too.  That is legal, if usually not
     460             :              * very sane, and this routine is only concerned with legality not
     461             :              * with whether the join is good strategy.
     462             :              *----------
     463             :              */
     464         224 :             if (match_sjinfo)
     465          80 :                 return false;   /* invalid join path */
     466         144 :             match_sjinfo = sjinfo;
     467         144 :             reversed = false;
     468         144 :             unique_ified = true;
     469             :         }
     470        8502 :         else if (sjinfo->jointype == JOIN_SEMI &&
     471        1664 :                  bms_equal(sjinfo->syn_righthand, rel1->relids) &&
     472         204 :                  create_unique_path(root, rel1, rel1->cheapest_total_path,
     473             :                                     sjinfo) != NULL)
     474             :         {
     475             :             /* Reversed semijoin case */
     476         204 :             if (match_sjinfo)
     477          44 :                 return false;   /* invalid join path */
     478         160 :             match_sjinfo = sjinfo;
     479         160 :             reversed = true;
     480         160 :             unique_ified = true;
     481             :         }
     482             :         else
     483             :         {
     484             :             /*
     485             :              * Otherwise, the proposed join overlaps the RHS but isn't a valid
     486             :              * implementation of this SJ.  But don't panic quite yet: the RHS
     487             :              * violation might have occurred previously, in one or both input
     488             :              * relations, in which case we must have previously decided that
     489             :              * it was OK to commute some other SJ with this one.  If we need
     490             :              * to perform this join to finish building up the RHS, rejecting
     491             :              * it could lead to not finding any plan at all.  (This can occur
     492             :              * because of the heuristics elsewhere in this file that postpone
     493             :              * clauseless joins: we might not consider doing a clauseless join
     494             :              * within the RHS until after we've performed other, validly
     495             :              * commutable SJs with one or both sides of the clauseless join.)
     496             :              * This consideration boils down to the rule that if both inputs
     497             :              * overlap the RHS, we can allow the join --- they are either
     498             :              * fully within the RHS, or represent previously-allowed joins to
     499             :              * rels outside it.
     500             :              */
     501        8482 :             if (bms_overlap(rel1->relids, sjinfo->min_righthand) &&
     502        1644 :                 bms_overlap(rel2->relids, sjinfo->min_righthand))
     503          80 :                 continue;       /* assume valid previous violation of RHS */
     504             : 
     505             :             /*
     506             :              * The proposed join could still be legal, but only if we're
     507             :              * allowed to associate it into the RHS of this SJ.  That means
     508             :              * this SJ must be a LEFT join (not SEMI or ANTI, and certainly
     509             :              * not FULL) and the proposed join must not overlap the LHS.
     510             :              */
     511       12164 :             if (sjinfo->jointype != JOIN_LEFT ||
     512        5406 :                 bms_overlap(joinrelids, sjinfo->min_lefthand))
     513        5018 :                 return false;   /* invalid join path */
     514             : 
     515             :             /*
     516             :              * To be valid, the proposed join must be a LEFT join; otherwise
     517             :              * it can't associate into this SJ's RHS.  But we may not yet have
     518             :              * found the SpecialJoinInfo matching the proposed join, so we
     519             :              * can't test that yet.  Remember the requirement for later.
     520             :              */
     521        1740 :             must_be_leftjoin = true;
     522             :         }
     523             :     }
     524             : 
     525             :     /*
     526             :      * Fail if violated any SJ's RHS and didn't match to a LEFT SJ: the
     527             :      * proposed join can't associate into an SJ's RHS.
     528             :      *
     529             :      * Also, fail if the proposed join's predicate isn't strict; we're
     530             :      * essentially checking to see if we can apply outer-join identity 3, and
     531             :      * that's a requirement.  (This check may be redundant with checks in
     532             :      * make_outerjoininfo, but I'm not quite sure, and it's cheap to test.)
     533             :      */
     534      145088 :     if (must_be_leftjoin &&
     535         560 :         (match_sjinfo == NULL ||
     536        1120 :          match_sjinfo->jointype != JOIN_LEFT ||
     537         560 :          !match_sjinfo->lhs_strict))
     538         692 :         return false;           /* invalid join path */
     539             : 
     540             :     /*
     541             :      * We also have to check for constraints imposed by LATERAL references.
     542             :      */
     543      144396 :     if (root->hasLateralRTEs)
     544             :     {
     545             :         bool        lateral_fwd;
     546             :         bool        lateral_rev;
     547             :         Relids      join_lateral_rels;
     548             : 
     549             :         /*
     550             :          * The proposed rels could each contain lateral references to the
     551             :          * other, in which case the join is impossible.  If there are lateral
     552             :          * references in just one direction, then the join has to be done with
     553             :          * a nestloop with the lateral referencer on the inside.  If the join
     554             :          * matches an SJ that cannot be implemented by such a nestloop, the
     555             :          * join is impossible.
     556             :          *
     557             :          * Also, if the lateral reference is only indirect, we should reject
     558             :          * the join; whatever rel(s) the reference chain goes through must be
     559             :          * joined to first.
     560             :          *
     561             :          * Another case that might keep us from building a valid plan is the
     562             :          * implementation restriction described by have_dangerous_phv().
     563             :          */
     564        3082 :         lateral_fwd = bms_overlap(rel1->relids, rel2->lateral_relids);
     565        3082 :         lateral_rev = bms_overlap(rel2->relids, rel1->lateral_relids);
     566        3082 :         if (lateral_fwd && lateral_rev)
     567          12 :             return false;       /* have lateral refs in both directions */
     568        3070 :         if (lateral_fwd)
     569             :         {
     570             :             /* has to be implemented as nestloop with rel1 on left */
     571        1058 :             if (match_sjinfo &&
     572          72 :                 (reversed ||
     573          64 :                  unique_ified ||
     574          64 :                  match_sjinfo->jointype == JOIN_FULL))
     575           8 :                 return false;   /* not implementable as nestloop */
     576             :             /* check there is a direct reference from rel2 to rel1 */
     577        1050 :             if (!bms_overlap(rel1->relids, rel2->direct_lateral_relids))
     578          12 :                 return false;   /* only indirect refs, so reject */
     579             :             /* check we won't have a dangerous PHV */
     580        1038 :             if (have_dangerous_phv(root, rel1->relids, rel2->lateral_relids))
     581          48 :                 return false;   /* might be unable to handle required PHV */
     582             :         }
     583        2012 :         else if (lateral_rev)
     584             :         {
     585             :             /* has to be implemented as nestloop with rel2 on left */
     586         438 :             if (match_sjinfo &&
     587          96 :                 (!reversed ||
     588          48 :                  unique_ified ||
     589          48 :                  match_sjinfo->jointype == JOIN_FULL))
     590           0 :                 return false;   /* not implementable as nestloop */
     591             :             /* check there is a direct reference from rel1 to rel2 */
     592         390 :             if (!bms_overlap(rel2->relids, rel1->direct_lateral_relids))
     593           0 :                 return false;   /* only indirect refs, so reject */
     594             :             /* check we won't have a dangerous PHV */
     595         390 :             if (have_dangerous_phv(root, rel2->relids, rel1->lateral_relids))
     596          56 :                 return false;   /* might be unable to handle required PHV */
     597             :         }
     598             : 
     599             :         /*
     600             :          * LATERAL references could also cause problems later on if we accept
     601             :          * this join: if the join's minimum parameterization includes any rels
     602             :          * that would have to be on the inside of an outer join with this join
     603             :          * rel, then it's never going to be possible to build the complete
     604             :          * query using this join.  We should reject this join not only because
     605             :          * it'll save work, but because if we don't, the clauseless-join
     606             :          * heuristics might think that legality of this join means that some
     607             :          * other join rel need not be formed, and that could lead to failure
     608             :          * to find any plan at all.  We have to consider not only rels that
     609             :          * are directly on the inner side of an OJ with the joinrel, but also
     610             :          * ones that are indirectly so, so search to find all such rels.
     611             :          */
     612        2946 :         join_lateral_rels = min_join_parameterization(root, joinrelids,
     613             :                                                       rel1, rel2);
     614        2946 :         if (join_lateral_rels)
     615             :         {
     616         562 :             Relids      join_plus_rhs = bms_copy(joinrelids);
     617             :             bool        more;
     618             : 
     619             :             do
     620             :             {
     621         690 :                 more = false;
     622        1246 :                 foreach(l, root->join_info_list)
     623             :                 {
     624         556 :                     SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(l);
     625             : 
     626             :                     /* ignore full joins --- their ordering is predetermined */
     627         556 :                     if (sjinfo->jointype == JOIN_FULL)
     628          12 :                         continue;
     629             : 
     630        1004 :                     if (bms_overlap(sjinfo->min_lefthand, join_plus_rhs) &&
     631         460 :                         !bms_is_subset(sjinfo->min_righthand, join_plus_rhs))
     632             :                     {
     633         188 :                         join_plus_rhs = bms_add_members(join_plus_rhs,
     634         188 :                                                         sjinfo->min_righthand);
     635         188 :                         more = true;
     636             :                     }
     637             :                 }
     638         690 :             } while (more);
     639         562 :             if (bms_overlap(join_plus_rhs, join_lateral_rels))
     640         128 :                 return false;   /* will not be able to join to some RHS rel */
     641             :         }
     642             :     }
     643             : 
     644             :     /* Otherwise, it's a valid join */
     645      144132 :     *sjinfo_p = match_sjinfo;
     646      144132 :     *reversed_p = reversed;
     647      144132 :     return true;
     648             : }
     649             : 
     650             : 
     651             : /*
     652             :  * make_join_rel
     653             :  *     Find or create a join RelOptInfo that represents the join of
     654             :  *     the two given rels, and add to it path information for paths
     655             :  *     created with the two rels as outer and inner rel.
     656             :  *     (The join rel may already contain paths generated from other
     657             :  *     pairs of rels that add up to the same set of base rels.)
     658             :  *
     659             :  * NB: will return NULL if attempted join is not valid.  This can happen
     660             :  * when working with outer joins, or with IN or EXISTS clauses that have been
     661             :  * turned into joins.
     662             :  */
     663             : RelOptInfo *
     664      150142 : make_join_rel(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2)
     665             : {
     666             :     Relids      joinrelids;
     667             :     SpecialJoinInfo *sjinfo;
     668             :     bool        reversed;
     669             :     SpecialJoinInfo sjinfo_data;
     670             :     RelOptInfo *joinrel;
     671             :     List       *restrictlist;
     672             : 
     673             :     /* We should never try to join two overlapping sets of rels. */
     674             :     Assert(!bms_overlap(rel1->relids, rel2->relids));
     675             : 
     676             :     /* Construct Relids set that identifies the joinrel. */
     677      150142 :     joinrelids = bms_union(rel1->relids, rel2->relids);
     678             : 
     679             :     /* Check validity and determine join type. */
     680      150142 :     if (!join_is_legal(root, rel1, rel2, joinrelids,
     681             :                        &sjinfo, &reversed))
     682             :     {
     683             :         /* invalid join path */
     684        6042 :         bms_free(joinrelids);
     685        6042 :         return NULL;
     686             :     }
     687             : 
     688             :     /* Swap rels if needed to match the join info. */
     689      144100 :     if (reversed)
     690             :     {
     691        2338 :         RelOptInfo *trel = rel1;
     692             : 
     693        2338 :         rel1 = rel2;
     694        2338 :         rel2 = trel;
     695             :     }
     696             : 
     697             :     /*
     698             :      * If it's a plain inner join, then we won't have found anything in
     699             :      * join_info_list.  Make up a SpecialJoinInfo so that selectivity
     700             :      * estimation functions will know what's being joined.
     701             :      */
     702      144100 :     if (sjinfo == NULL)
     703             :     {
     704       79034 :         sjinfo = &sjinfo_data;
     705       79034 :         sjinfo->type = T_SpecialJoinInfo;
     706       79034 :         sjinfo->min_lefthand = rel1->relids;
     707       79034 :         sjinfo->min_righthand = rel2->relids;
     708       79034 :         sjinfo->syn_lefthand = rel1->relids;
     709       79034 :         sjinfo->syn_righthand = rel2->relids;
     710       79034 :         sjinfo->jointype = JOIN_INNER;
     711             :         /* we don't bother trying to make the remaining fields valid */
     712       79034 :         sjinfo->lhs_strict = false;
     713       79034 :         sjinfo->delay_upper_joins = false;
     714       79034 :         sjinfo->semi_can_btree = false;
     715       79034 :         sjinfo->semi_can_hash = false;
     716       79034 :         sjinfo->semi_operators = NIL;
     717       79034 :         sjinfo->semi_rhs_exprs = NIL;
     718             :     }
     719             : 
     720             :     /*
     721             :      * Find or build the join RelOptInfo, and compute the restrictlist that
     722             :      * goes with this particular joining.
     723             :      */
     724      144100 :     joinrel = build_join_rel(root, joinrelids, rel1, rel2, sjinfo,
     725             :                              &restrictlist);
     726             : 
     727             :     /*
     728             :      * If we've already proven this join is empty, we needn't consider any
     729             :      * more paths for it.
     730             :      */
     731      144100 :     if (is_dummy_rel(joinrel))
     732             :     {
     733         232 :         bms_free(joinrelids);
     734         232 :         return joinrel;
     735             :     }
     736             : 
     737             :     /* Add paths to the join relation. */
     738      143868 :     populate_joinrel_with_paths(root, rel1, rel2, joinrel, sjinfo,
     739             :                                 restrictlist);
     740             : 
     741      143868 :     bms_free(joinrelids);
     742             : 
     743      143868 :     return joinrel;
     744             : }
     745             : 
     746             : /*
     747             :  * populate_joinrel_with_paths
     748             :  *    Add paths to the given joinrel for given pair of joining relations. The
     749             :  *    SpecialJoinInfo provides details about the join and the restrictlist
     750             :  *    contains the join clauses and the other clauses applicable for given pair
     751             :  *    of the joining relations.
     752             :  */
     753             : static void
     754      145500 : populate_joinrel_with_paths(PlannerInfo *root, RelOptInfo *rel1,
     755             :                             RelOptInfo *rel2, RelOptInfo *joinrel,
     756             :                             SpecialJoinInfo *sjinfo, List *restrictlist)
     757             : {
     758             :     /*
     759             :      * Consider paths using each rel as both outer and inner.  Depending on
     760             :      * the join type, a provably empty outer or inner rel might mean the join
     761             :      * is provably empty too; in which case throw away any previously computed
     762             :      * paths and mark the join as dummy.  (We do it this way since it's
     763             :      * conceivable that dummy-ness of a multi-element join might only be
     764             :      * noticeable for certain construction paths.)
     765             :      *
     766             :      * Also, a provably constant-false join restriction typically means that
     767             :      * we can skip evaluating one or both sides of the join.  We do this by
     768             :      * marking the appropriate rel as dummy.  For outer joins, a
     769             :      * constant-false restriction that is pushed down still means the whole
     770             :      * join is dummy, while a non-pushed-down one means that no inner rows
     771             :      * will join so we can treat the inner rel as dummy.
     772             :      *
     773             :      * We need only consider the jointypes that appear in join_info_list, plus
     774             :      * JOIN_INNER.
     775             :      */
     776      145500 :     switch (sjinfo->jointype)
     777             :     {
     778             :         case JOIN_INNER:
     779      159168 :             if (is_dummy_rel(rel1) || is_dummy_rel(rel2) ||
     780       79578 :                 restriction_is_constant_false(restrictlist, joinrel, false))
     781             :             {
     782          76 :                 mark_dummy_rel(joinrel);
     783          76 :                 break;
     784             :             }
     785       79514 :             add_paths_to_joinrel(root, joinrel, rel1, rel2,
     786             :                                  JOIN_INNER, sjinfo,
     787             :                                  restrictlist);
     788       79514 :             add_paths_to_joinrel(root, joinrel, rel2, rel1,
     789             :                                  JOIN_INNER, sjinfo,
     790             :                                  restrictlist);
     791       79514 :             break;
     792             :         case JOIN_LEFT:
     793      107136 :             if (is_dummy_rel(rel1) ||
     794       53564 :                 restriction_is_constant_false(restrictlist, joinrel, true))
     795             :             {
     796          20 :                 mark_dummy_rel(joinrel);
     797          20 :                 break;
     798             :             }
     799       53560 :             if (restriction_is_constant_false(restrictlist, joinrel, false) &&
     800           8 :                 bms_is_subset(rel2->relids, sjinfo->syn_righthand))
     801           8 :                 mark_dummy_rel(rel2);
     802       53552 :             add_paths_to_joinrel(root, joinrel, rel1, rel2,
     803             :                                  JOIN_LEFT, sjinfo,
     804             :                                  restrictlist);
     805       53552 :             add_paths_to_joinrel(root, joinrel, rel2, rel1,
     806             :                                  JOIN_RIGHT, sjinfo,
     807             :                                  restrictlist);
     808       53552 :             break;
     809             :         case JOIN_FULL:
     810        1272 :             if ((is_dummy_rel(rel1) && is_dummy_rel(rel2)) ||
     811         636 :                 restriction_is_constant_false(restrictlist, joinrel, true))
     812             :             {
     813           0 :                 mark_dummy_rel(joinrel);
     814           0 :                 break;
     815             :             }
     816         636 :             add_paths_to_joinrel(root, joinrel, rel1, rel2,
     817             :                                  JOIN_FULL, sjinfo,
     818             :                                  restrictlist);
     819         636 :             add_paths_to_joinrel(root, joinrel, rel2, rel1,
     820             :                                  JOIN_FULL, sjinfo,
     821             :                                  restrictlist);
     822             : 
     823             :             /*
     824             :              * If there are join quals that aren't mergeable or hashable, we
     825             :              * may not be able to build any valid plan.  Complain here so that
     826             :              * we can give a somewhat-useful error message.  (Since we have no
     827             :              * flexibility of planning for a full join, there's no chance of
     828             :              * succeeding later with another pair of input rels.)
     829             :              */
     830         636 :             if (joinrel->pathlist == NIL)
     831           0 :                 ereport(ERROR,
     832             :                         (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
     833             :                          errmsg("FULL JOIN is only supported with merge-joinable or hash-joinable join conditions")));
     834         636 :             break;
     835             :         case JOIN_SEMI:
     836             : 
     837             :             /*
     838             :              * We might have a normal semijoin, or a case where we don't have
     839             :              * enough rels to do the semijoin but can unique-ify the RHS and
     840             :              * then do an innerjoin (see comments in join_is_legal).  In the
     841             :              * latter case we can't apply JOIN_SEMI joining.
     842             :              */
     843        3608 :             if (bms_is_subset(sjinfo->min_lefthand, rel1->relids) &&
     844        1798 :                 bms_is_subset(sjinfo->min_righthand, rel2->relids))
     845             :             {
     846        3592 :                 if (is_dummy_rel(rel1) || is_dummy_rel(rel2) ||
     847        1794 :                     restriction_is_constant_false(restrictlist, joinrel, false))
     848             :                 {
     849           8 :                     mark_dummy_rel(joinrel);
     850           8 :                     break;
     851             :                 }
     852        1790 :                 add_paths_to_joinrel(root, joinrel, rel1, rel2,
     853             :                                      JOIN_SEMI, sjinfo,
     854             :                                      restrictlist);
     855             :             }
     856             : 
     857             :             /*
     858             :              * If we know how to unique-ify the RHS and one input rel is
     859             :              * exactly the RHS (not a superset) we can consider unique-ifying
     860             :              * it and then doing a regular join.  (The create_unique_path
     861             :              * check here is probably redundant with what join_is_legal did,
     862             :              * but if so the check is cheap because it's cached.  So test
     863             :              * anyway to be sure.)
     864             :              */
     865        3604 :             if (bms_equal(sjinfo->syn_righthand, rel2->relids) &&
     866        1802 :                 create_unique_path(root, rel2, rel2->cheapest_total_path,
     867             :                                    sjinfo) != NULL)
     868             :             {
     869        3488 :                 if (is_dummy_rel(rel1) || is_dummy_rel(rel2) ||
     870        1744 :                     restriction_is_constant_false(restrictlist, joinrel, false))
     871             :                 {
     872           0 :                     mark_dummy_rel(joinrel);
     873           0 :                     break;
     874             :                 }
     875        1744 :                 add_paths_to_joinrel(root, joinrel, rel1, rel2,
     876             :                                      JOIN_UNIQUE_INNER, sjinfo,
     877             :                                      restrictlist);
     878        1744 :                 add_paths_to_joinrel(root, joinrel, rel2, rel1,
     879             :                                      JOIN_UNIQUE_OUTER, sjinfo,
     880             :                                      restrictlist);
     881             :             }
     882        1802 :             break;
     883             :         case JOIN_ANTI:
     884       19784 :             if (is_dummy_rel(rel1) ||
     885        9892 :                 restriction_is_constant_false(restrictlist, joinrel, true))
     886             :             {
     887           0 :                 mark_dummy_rel(joinrel);
     888           0 :                 break;
     889             :             }
     890        9892 :             if (restriction_is_constant_false(restrictlist, joinrel, false) &&
     891           0 :                 bms_is_subset(rel2->relids, sjinfo->syn_righthand))
     892           0 :                 mark_dummy_rel(rel2);
     893        9892 :             add_paths_to_joinrel(root, joinrel, rel1, rel2,
     894             :                                  JOIN_ANTI, sjinfo,
     895             :                                  restrictlist);
     896        9892 :             break;
     897             :         default:
     898             :             /* other values not expected here */
     899           0 :             elog(ERROR, "unrecognized join type: %d", (int) sjinfo->jointype);
     900             :             break;
     901             :     }
     902             : 
     903             :     /* Apply partitionwise join technique, if possible. */
     904      145500 :     try_partitionwise_join(root, rel1, rel2, joinrel, sjinfo, restrictlist);
     905      145500 : }
     906             : 
     907             : 
     908             : /*
     909             :  * have_join_order_restriction
     910             :  *      Detect whether the two relations should be joined to satisfy
     911             :  *      a join-order restriction arising from special or lateral joins.
     912             :  *
     913             :  * In practice this is always used with have_relevant_joinclause(), and so
     914             :  * could be merged with that function, but it seems clearer to separate the
     915             :  * two concerns.  We need this test because there are degenerate cases where
     916             :  * a clauseless join must be performed to satisfy join-order restrictions.
     917             :  * Also, if one rel has a lateral reference to the other, or both are needed
     918             :  * to compute some PHV, we should consider joining them even if the join would
     919             :  * be clauseless.
     920             :  *
     921             :  * Note: this is only a problem if one side of a degenerate outer join
     922             :  * contains multiple rels, or a clauseless join is required within an
     923             :  * IN/EXISTS RHS; else we will find a join path via the "last ditch" case in
     924             :  * join_search_one_level().  We could dispense with this test if we were
     925             :  * willing to try bushy plans in the "last ditch" case, but that seems much
     926             :  * less efficient.
     927             :  */
     928             : bool
     929       28050 : have_join_order_restriction(PlannerInfo *root,
     930             :                             RelOptInfo *rel1, RelOptInfo *rel2)
     931             : {
     932       28050 :     bool        result = false;
     933             :     ListCell   *l;
     934             : 
     935             :     /*
     936             :      * If either side has a direct lateral reference to the other, attempt the
     937             :      * join regardless of outer-join considerations.
     938             :      */
     939       55232 :     if (bms_overlap(rel1->relids, rel2->direct_lateral_relids) ||
     940       27182 :         bms_overlap(rel2->relids, rel1->direct_lateral_relids))
     941        1078 :         return true;
     942             : 
     943             :     /*
     944             :      * Likewise, if both rels are needed to compute some PlaceHolderVar,
     945             :      * attempt the join regardless of outer-join considerations.  (This is not
     946             :      * very desirable, because a PHV with a large eval_at set will cause a lot
     947             :      * of probably-useless joins to be considered, but failing to do this can
     948             :      * cause us to fail to construct a plan at all.)
     949             :      */
     950       27700 :     foreach(l, root->placeholder_list)
     951             :     {
     952         760 :         PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(l);
     953             : 
     954         932 :         if (bms_is_subset(rel1->relids, phinfo->ph_eval_at) &&
     955         172 :             bms_is_subset(rel2->relids, phinfo->ph_eval_at))
     956          32 :             return true;
     957             :     }
     958             : 
     959             :     /*
     960             :      * It's possible that the rels correspond to the left and right sides of a
     961             :      * degenerate outer join, that is, one with no joinclause mentioning the
     962             :      * non-nullable side; in which case we should force the join to occur.
     963             :      *
     964             :      * Also, the two rels could represent a clauseless join that has to be
     965             :      * completed to build up the LHS or RHS of an outer join.
     966             :      */
     967       75958 :     foreach(l, root->join_info_list)
     968             :     {
     969       49264 :         SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(l);
     970             : 
     971             :         /* ignore full joins --- other mechanisms handle them */
     972       49264 :         if (sjinfo->jointype == JOIN_FULL)
     973           8 :             continue;
     974             : 
     975             :         /* Can we perform the SJ with these rels? */
     976       56744 :         if (bms_is_subset(sjinfo->min_lefthand, rel1->relids) &&
     977        7488 :             bms_is_subset(sjinfo->min_righthand, rel2->relids))
     978             :         {
     979         154 :             result = true;
     980         154 :             break;
     981             :         }
     982       50784 :         if (bms_is_subset(sjinfo->min_lefthand, rel2->relids) &&
     983        1682 :             bms_is_subset(sjinfo->min_righthand, rel1->relids))
     984             :         {
     985          36 :             result = true;
     986          36 :             break;
     987             :         }
     988             : 
     989             :         /*
     990             :          * Might we need to join these rels to complete the RHS?  We have to
     991             :          * use "overlap" tests since either rel might include a lower SJ that
     992             :          * has been proven to commute with this one.
     993             :          */
     994       57640 :         if (bms_overlap(sjinfo->min_righthand, rel1->relids) &&
     995        8574 :             bms_overlap(sjinfo->min_righthand, rel2->relids))
     996             :         {
     997          44 :             result = true;
     998          44 :             break;
     999             :         }
    1000             : 
    1001             :         /* Likewise for the LHS. */
    1002       58112 :         if (bms_overlap(sjinfo->min_lefthand, rel1->relids) &&
    1003        9090 :             bms_overlap(sjinfo->min_lefthand, rel2->relids))
    1004             :         {
    1005          12 :             result = true;
    1006          12 :             break;
    1007             :         }
    1008             :     }
    1009             : 
    1010             :     /*
    1011             :      * We do not force the join to occur if either input rel can legally be
    1012             :      * joined to anything else using joinclauses.  This essentially means that
    1013             :      * clauseless bushy joins are put off as long as possible. The reason is
    1014             :      * that when there is a join order restriction high up in the join tree
    1015             :      * (that is, with many rels inside the LHS or RHS), we would otherwise
    1016             :      * expend lots of effort considering very stupid join combinations within
    1017             :      * its LHS or RHS.
    1018             :      */
    1019       26940 :     if (result)
    1020             :     {
    1021         476 :         if (has_legal_joinclause(root, rel1) ||
    1022         230 :             has_legal_joinclause(root, rel2))
    1023          32 :             result = false;
    1024             :     }
    1025             : 
    1026       26940 :     return result;
    1027             : }
    1028             : 
    1029             : 
    1030             : /*
    1031             :  * has_join_restriction
    1032             :  *      Detect whether the specified relation has join-order restrictions,
    1033             :  *      due to being inside an outer join or an IN (sub-SELECT),
    1034             :  *      or participating in any LATERAL references or multi-rel PHVs.
    1035             :  *
    1036             :  * Essentially, this tests whether have_join_order_restriction() could
    1037             :  * succeed with this rel and some other one.  It's OK if we sometimes
    1038             :  * say "true" incorrectly.  (Therefore, we don't bother with the relatively
    1039             :  * expensive has_legal_joinclause test.)
    1040             :  */
    1041             : static bool
    1042        5974 : has_join_restriction(PlannerInfo *root, RelOptInfo *rel)
    1043             : {
    1044             :     ListCell   *l;
    1045             : 
    1046        5974 :     if (rel->lateral_relids != NULL || rel->lateral_referencers != NULL)
    1047        1202 :         return true;
    1048             : 
    1049        4968 :     foreach(l, root->placeholder_list)
    1050             :     {
    1051         220 :         PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(l);
    1052             : 
    1053         264 :         if (bms_is_subset(rel->relids, phinfo->ph_eval_at) &&
    1054          44 :             !bms_equal(rel->relids, phinfo->ph_eval_at))
    1055          24 :             return true;
    1056             :     }
    1057             : 
    1058        4932 :     foreach(l, root->join_info_list)
    1059             :     {
    1060         566 :         SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(l);
    1061             : 
    1062             :         /* ignore full joins --- other mechanisms preserve their ordering */
    1063         566 :         if (sjinfo->jointype == JOIN_FULL)
    1064          44 :             continue;
    1065             : 
    1066             :         /* ignore if SJ is already contained in rel */
    1067         778 :         if (bms_is_subset(sjinfo->min_lefthand, rel->relids) &&
    1068         256 :             bms_is_subset(sjinfo->min_righthand, rel->relids))
    1069          98 :             continue;
    1070             : 
    1071             :         /* restricted if it overlaps LHS or RHS, but doesn't contain SJ */
    1072         682 :         if (bms_overlap(sjinfo->min_lefthand, rel->relids) ||
    1073         258 :             bms_overlap(sjinfo->min_righthand, rel->relids))
    1074         382 :             return true;
    1075             :     }
    1076             : 
    1077        4366 :     return false;
    1078             : }
    1079             : 
    1080             : 
    1081             : /*
    1082             :  * has_legal_joinclause
    1083             :  *      Detect whether the specified relation can legally be joined
    1084             :  *      to any other rels using join clauses.
    1085             :  *
    1086             :  * We consider only joins to single other relations in the current
    1087             :  * initial_rels list.  This is sufficient to get a "true" result in most real
    1088             :  * queries, and an occasional erroneous "false" will only cost a bit more
    1089             :  * planning time.  The reason for this limitation is that considering joins to
    1090             :  * other joins would require proving that the other join rel can legally be
    1091             :  * formed, which seems like too much trouble for something that's only a
    1092             :  * heuristic to save planning time.  (Note: we must look at initial_rels
    1093             :  * and not all of the query, since when we are planning a sub-joinlist we
    1094             :  * may be forced to make clauseless joins within initial_rels even though
    1095             :  * there are join clauses linking to other parts of the query.)
    1096             :  */
    1097             : static bool
    1098         476 : has_legal_joinclause(PlannerInfo *root, RelOptInfo *rel)
    1099             : {
    1100             :     ListCell   *lc;
    1101             : 
    1102        1832 :     foreach(lc, root->initial_rels)
    1103             :     {
    1104        1388 :         RelOptInfo *rel2 = (RelOptInfo *) lfirst(lc);
    1105             : 
    1106             :         /* ignore rels that are already in "rel" */
    1107        1388 :         if (bms_overlap(rel->relids, rel2->relids))
    1108         554 :             continue;
    1109             : 
    1110         834 :         if (have_relevant_joinclause(root, rel, rel2))
    1111             :         {
    1112             :             Relids      joinrelids;
    1113             :             SpecialJoinInfo *sjinfo;
    1114             :             bool        reversed;
    1115             : 
    1116             :             /* join_is_legal needs relids of the union */
    1117          88 :             joinrelids = bms_union(rel->relids, rel2->relids);
    1118             : 
    1119          88 :             if (join_is_legal(root, rel, rel2, joinrelids,
    1120             :                               &sjinfo, &reversed))
    1121             :             {
    1122             :                 /* Yes, this will work */
    1123          32 :                 bms_free(joinrelids);
    1124          32 :                 return true;
    1125             :             }
    1126             : 
    1127          56 :             bms_free(joinrelids);
    1128             :         }
    1129             :     }
    1130             : 
    1131         444 :     return false;
    1132             : }
    1133             : 
    1134             : 
    1135             : /*
    1136             :  * There's a pitfall for creating parameterized nestloops: suppose the inner
    1137             :  * rel (call it A) has a parameter that is a PlaceHolderVar, and that PHV's
    1138             :  * minimum eval_at set includes the outer rel (B) and some third rel (C).
    1139             :  * We might think we could create a B/A nestloop join that's parameterized by
    1140             :  * C.  But we would end up with a plan in which the PHV's expression has to be
    1141             :  * evaluated as a nestloop parameter at the B/A join; and the executor is only
    1142             :  * set up to handle simple Vars as NestLoopParams.  Rather than add complexity
    1143             :  * and overhead to the executor for such corner cases, it seems better to
    1144             :  * forbid the join.  (Note that we can still make use of A's parameterized
    1145             :  * path with pre-joined B+C as the outer rel.  have_join_order_restriction()
    1146             :  * ensures that we will consider making such a join even if there are not
    1147             :  * other reasons to do so.)
    1148             :  *
    1149             :  * So we check whether any PHVs used in the query could pose such a hazard.
    1150             :  * We don't have any simple way of checking whether a risky PHV would actually
    1151             :  * be used in the inner plan, and the case is so unusual that it doesn't seem
    1152             :  * worth working very hard on it.
    1153             :  *
    1154             :  * This needs to be checked in two places.  If the inner rel's minimum
    1155             :  * parameterization would trigger the restriction, then join_is_legal() should
    1156             :  * reject the join altogether, because there will be no workable paths for it.
    1157             :  * But joinpath.c has to check again for every proposed nestloop path, because
    1158             :  * the inner path might have more than the minimum parameterization, causing
    1159             :  * some PHV to be dangerous for it that otherwise wouldn't be.
    1160             :  */
    1161             : bool
    1162        8964 : have_dangerous_phv(PlannerInfo *root,
    1163             :                    Relids outer_relids, Relids inner_params)
    1164             : {
    1165             :     ListCell   *lc;
    1166             : 
    1167       10332 :     foreach(lc, root->placeholder_list)
    1168             :     {
    1169        1536 :         PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(lc);
    1170             : 
    1171        1536 :         if (!bms_is_subset(phinfo->ph_eval_at, inner_params))
    1172        1128 :             continue;           /* ignore, could not be a nestloop param */
    1173         408 :         if (!bms_overlap(phinfo->ph_eval_at, outer_relids))
    1174          88 :             continue;           /* ignore, not relevant to this join */
    1175         320 :         if (bms_is_subset(phinfo->ph_eval_at, outer_relids))
    1176         152 :             continue;           /* safe, it can be eval'd within outerrel */
    1177             :         /* Otherwise, it's potentially unsafe, so reject the join */
    1178         168 :         return true;
    1179             :     }
    1180             : 
    1181             :     /* OK to perform the join */
    1182        8796 :     return false;
    1183             : }
    1184             : 
    1185             : 
    1186             : /*
    1187             :  * is_dummy_rel --- has relation been proven empty?
    1188             :  */
    1189             : bool
    1190     1181458 : is_dummy_rel(RelOptInfo *rel)
    1191             : {
    1192             :     Path       *path;
    1193             : 
    1194             :     /*
    1195             :      * A rel that is known dummy will have just one path that is a childless
    1196             :      * Append.  (Even if somehow it has more paths, a childless Append will
    1197             :      * have cost zero and hence should be at the front of the pathlist.)
    1198             :      */
    1199     1181458 :     if (rel->pathlist == NIL)
    1200      711756 :         return false;
    1201      469702 :     path = (Path *) linitial(rel->pathlist);
    1202             : 
    1203             :     /*
    1204             :      * Initially, a dummy path will just be a childless Append.  But in later
    1205             :      * planning stages we might stick a ProjectSetPath and/or ProjectionPath
    1206             :      * on top, since Append can't project.  Rather than make assumptions about
    1207             :      * which combinations can occur, just descend through whatever we find.
    1208             :      */
    1209             :     for (;;)
    1210             :     {
    1211      493246 :         if (IsA(path, ProjectionPath))
    1212        9590 :             path = ((ProjectionPath *) path)->subpath;
    1213      471884 :         else if (IsA(path, ProjectSetPath))
    1214        2182 :             path = ((ProjectSetPath *) path)->subpath;
    1215             :         else
    1216      469702 :             break;
    1217             :     }
    1218      469702 :     if (IS_DUMMY_APPEND(path))
    1219        1928 :         return true;
    1220      467774 :     return false;
    1221             : }
    1222             : 
    1223             : /*
    1224             :  * Mark a relation as proven empty.
    1225             :  *
    1226             :  * During GEQO planning, this can get invoked more than once on the same
    1227             :  * baserel struct, so it's worth checking to see if the rel is already marked
    1228             :  * dummy.
    1229             :  *
    1230             :  * Also, when called during GEQO join planning, we are in a short-lived
    1231             :  * memory context.  We must make sure that the dummy path attached to a
    1232             :  * baserel survives the GEQO cycle, else the baserel is trashed for future
    1233             :  * GEQO cycles.  On the other hand, when we are marking a joinrel during GEQO,
    1234             :  * we don't want the dummy path to clutter the main planning context.  Upshot
    1235             :  * is that the best solution is to explicitly make the dummy path in the same
    1236             :  * context the given RelOptInfo is in.
    1237             :  */
    1238             : void
    1239         164 : mark_dummy_rel(RelOptInfo *rel)
    1240             : {
    1241             :     MemoryContext oldcontext;
    1242             : 
    1243             :     /* Already marked? */
    1244         164 :     if (is_dummy_rel(rel))
    1245           0 :         return;
    1246             : 
    1247             :     /* No, so choose correct context to make the dummy path in */
    1248         164 :     oldcontext = MemoryContextSwitchTo(GetMemoryChunkContext(rel));
    1249             : 
    1250             :     /* Set dummy size estimate */
    1251         164 :     rel->rows = 0;
    1252             : 
    1253             :     /* Evict any previously chosen paths */
    1254         164 :     rel->pathlist = NIL;
    1255         164 :     rel->partial_pathlist = NIL;
    1256             : 
    1257             :     /* Set up the dummy path */
    1258         164 :     add_path(rel, (Path *) create_append_path(NULL, rel, NIL, NIL,
    1259             :                                               NIL, rel->lateral_relids,
    1260             :                                               0, false, NIL, -1));
    1261             : 
    1262             :     /* Set or update cheapest_total_path and related fields */
    1263         164 :     set_cheapest(rel);
    1264             : 
    1265         164 :     MemoryContextSwitchTo(oldcontext);
    1266             : }
    1267             : 
    1268             : 
    1269             : /*
    1270             :  * restriction_is_constant_false --- is a restrictlist just FALSE?
    1271             :  *
    1272             :  * In cases where a qual is provably constant FALSE, eval_const_expressions
    1273             :  * will generally have thrown away anything that's ANDed with it.  In outer
    1274             :  * join situations this will leave us computing cartesian products only to
    1275             :  * decide there's no match for an outer row, which is pretty stupid.  So,
    1276             :  * we need to detect the case.
    1277             :  *
    1278             :  * If only_pushed_down is true, then consider only quals that are pushed-down
    1279             :  * from the point of view of the joinrel.
    1280             :  */
    1281             : static bool
    1282      210652 : restriction_is_constant_false(List *restrictlist,
    1283             :                               RelOptInfo *joinrel,
    1284             :                               bool only_pushed_down)
    1285             : {
    1286             :     ListCell   *lc;
    1287             : 
    1288             :     /*
    1289             :      * Despite the above comment, the restriction list we see here might
    1290             :      * possibly have other members besides the FALSE constant, since other
    1291             :      * quals could get "pushed down" to the outer join level.  So we check
    1292             :      * each member of the list.
    1293             :      */
    1294      462480 :     foreach(lc, restrictlist)
    1295             :     {
    1296      251916 :         RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
    1297             : 
    1298      251916 :         if (only_pushed_down && !RINFO_IS_PUSHED_DOWN(rinfo, joinrel->relids))
    1299       86088 :             continue;
    1300             : 
    1301      165828 :         if (rinfo->clause && IsA(rinfo->clause, Const))
    1302             :         {
    1303          88 :             Const      *con = (Const *) rinfo->clause;
    1304             : 
    1305             :             /* constant NULL is as good as constant FALSE for our purposes */
    1306          88 :             if (con->constisnull)
    1307           0 :                 return true;
    1308          88 :             if (!DatumGetBool(con->constvalue))
    1309          88 :                 return true;
    1310             :         }
    1311             :     }
    1312      210564 :     return false;
    1313             : }
    1314             : 
    1315             : /*
    1316             :  * Assess whether join between given two partitioned relations can be broken
    1317             :  * down into joins between matching partitions; a technique called
    1318             :  * "partitionwise join"
    1319             :  *
    1320             :  * Partitionwise join is possible when a. Joining relations have same
    1321             :  * partitioning scheme b. There exists an equi-join between the partition keys
    1322             :  * of the two relations.
    1323             :  *
    1324             :  * Partitionwise join is planned as follows (details: optimizer/README.)
    1325             :  *
    1326             :  * 1. Create the RelOptInfos for joins between matching partitions i.e
    1327             :  * child-joins and add paths to them.
    1328             :  *
    1329             :  * 2. Construct Append or MergeAppend paths across the set of child joins.
    1330             :  * This second phase is implemented by generate_partitionwise_join_paths().
    1331             :  *
    1332             :  * The RelOptInfo, SpecialJoinInfo and restrictlist for each child join are
    1333             :  * obtained by translating the respective parent join structures.
    1334             :  */
    1335             : static void
    1336      145500 : try_partitionwise_join(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
    1337             :                        RelOptInfo *joinrel, SpecialJoinInfo *parent_sjinfo,
    1338             :                        List *parent_restrictlist)
    1339             : {
    1340      145500 :     bool        rel1_is_simple = IS_SIMPLE_REL(rel1);
    1341      145500 :     bool        rel2_is_simple = IS_SIMPLE_REL(rel2);
    1342             :     int         nparts;
    1343             :     int         cnt_parts;
    1344             : 
    1345             :     /* Guard against stack overflow due to overly deep partition hierarchy. */
    1346      145500 :     check_stack_depth();
    1347             : 
    1348             :     /* Nothing to do, if the join relation is not partitioned. */
    1349      145500 :     if (!IS_PARTITIONED_REL(joinrel))
    1350      144884 :         return;
    1351             : 
    1352             :     /* The join relation should have consider_partitionwise_join set. */
    1353             :     Assert(joinrel->consider_partitionwise_join);
    1354             : 
    1355             :     /*
    1356             :      * Since this join relation is partitioned, all the base relations
    1357             :      * participating in this join must be partitioned and so are all the
    1358             :      * intermediate join relations.
    1359             :      */
    1360             :     Assert(IS_PARTITIONED_REL(rel1) && IS_PARTITIONED_REL(rel2));
    1361             :     Assert(REL_HAS_ALL_PART_PROPS(rel1) && REL_HAS_ALL_PART_PROPS(rel2));
    1362             : 
    1363             :     /* The joining relations should have consider_partitionwise_join set. */
    1364             :     Assert(rel1->consider_partitionwise_join &&
    1365             :            rel2->consider_partitionwise_join);
    1366             : 
    1367             :     /*
    1368             :      * The partition scheme of the join relation should match that of the
    1369             :      * joining relations.
    1370             :      */
    1371             :     Assert(joinrel->part_scheme == rel1->part_scheme &&
    1372             :            joinrel->part_scheme == rel2->part_scheme);
    1373             : 
    1374             :     /*
    1375             :      * Since we allow partitionwise join only when the partition bounds of the
    1376             :      * joining relations exactly match, the partition bounds of the join
    1377             :      * should match those of the joining relations.
    1378             :      */
    1379             :     Assert(partition_bounds_equal(joinrel->part_scheme->partnatts,
    1380             :                                   joinrel->part_scheme->parttyplen,
    1381             :                                   joinrel->part_scheme->parttypbyval,
    1382             :                                   joinrel->boundinfo, rel1->boundinfo));
    1383             :     Assert(partition_bounds_equal(joinrel->part_scheme->partnatts,
    1384             :                                   joinrel->part_scheme->parttyplen,
    1385             :                                   joinrel->part_scheme->parttypbyval,
    1386             :                                   joinrel->boundinfo, rel2->boundinfo));
    1387             : 
    1388         616 :     nparts = joinrel->nparts;
    1389             : 
    1390             :     /*
    1391             :      * Create child-join relations for this partitioned join, if those don't
    1392             :      * exist. Add paths to child-joins for a pair of child relations
    1393             :      * corresponding to the given pair of parent relations.
    1394             :      */
    1395        2268 :     for (cnt_parts = 0; cnt_parts < nparts; cnt_parts++)
    1396             :     {
    1397        1692 :         RelOptInfo *child_rel1 = rel1->part_rels[cnt_parts];
    1398        1692 :         RelOptInfo *child_rel2 = rel2->part_rels[cnt_parts];
    1399        3372 :         bool        rel1_empty = (child_rel1 == NULL ||
    1400        1680 :                                   IS_DUMMY_REL(child_rel1));
    1401        3336 :         bool        rel2_empty = (child_rel2 == NULL ||
    1402        1644 :                                   IS_DUMMY_REL(child_rel2));
    1403             :         SpecialJoinInfo *child_sjinfo;
    1404             :         List       *child_restrictlist;
    1405             :         RelOptInfo *child_joinrel;
    1406             :         Relids      child_joinrelids;
    1407             :         AppendRelInfo **appinfos;
    1408             :         int         nappinfos;
    1409             : 
    1410             :         /*
    1411             :          * Check for cases where we can prove that this segment of the join
    1412             :          * returns no rows, due to one or both inputs being empty (including
    1413             :          * inputs that have been pruned away entirely).  If so just ignore it.
    1414             :          * These rules are equivalent to populate_joinrel_with_paths's rules
    1415             :          * for dummy input relations.
    1416             :          */
    1417        1692 :         switch (parent_sjinfo->jointype)
    1418             :         {
    1419             :             case JOIN_INNER:
    1420             :             case JOIN_SEMI:
    1421         948 :                 if (rel1_empty || rel2_empty)
    1422          36 :                     continue;   /* ignore this join segment */
    1423         932 :                 break;
    1424             :             case JOIN_LEFT:
    1425             :             case JOIN_ANTI:
    1426         560 :                 if (rel1_empty)
    1427           4 :                     continue;   /* ignore this join segment */
    1428         556 :                 break;
    1429             :             case JOIN_FULL:
    1430         184 :                 if (rel1_empty && rel2_empty)
    1431           0 :                     continue;   /* ignore this join segment */
    1432         184 :                 break;
    1433             :             default:
    1434             :                 /* other values not expected here */
    1435           0 :                 elog(ERROR, "unrecognized join type: %d",
    1436             :                      (int) parent_sjinfo->jointype);
    1437             :                 break;
    1438             :         }
    1439             : 
    1440             :         /*
    1441             :          * If a child has been pruned entirely then we can't generate paths
    1442             :          * for it, so we have to reject partitionwise joining unless we were
    1443             :          * able to eliminate this partition above.
    1444             :          */
    1445        1672 :         if (child_rel1 == NULL || child_rel2 == NULL)
    1446             :         {
    1447             :             /*
    1448             :              * Mark the joinrel as unpartitioned so that later functions treat
    1449             :              * it correctly.
    1450             :              */
    1451          40 :             joinrel->nparts = 0;
    1452          80 :             return;
    1453             :         }
    1454             : 
    1455             :         /*
    1456             :          * If a leaf relation has consider_partitionwise_join=false, it means
    1457             :          * that it's a dummy relation for which we skipped setting up tlist
    1458             :          * expressions and adding EC members in set_append_rel_size(), so
    1459             :          * again we have to fail here.
    1460             :          */
    1461        1632 :         if (rel1_is_simple && !child_rel1->consider_partitionwise_join)
    1462             :         {
    1463             :             Assert(child_rel1->reloptkind == RELOPT_OTHER_MEMBER_REL);
    1464             :             Assert(IS_DUMMY_REL(child_rel1));
    1465           0 :             joinrel->nparts = 0;
    1466           0 :             return;
    1467             :         }
    1468        1632 :         if (rel2_is_simple && !child_rel2->consider_partitionwise_join)
    1469             :         {
    1470             :             Assert(child_rel2->reloptkind == RELOPT_OTHER_MEMBER_REL);
    1471             :             Assert(IS_DUMMY_REL(child_rel2));
    1472           0 :             joinrel->nparts = 0;
    1473           0 :             return;
    1474             :         }
    1475             : 
    1476             :         /* We should never try to join two overlapping sets of rels. */
    1477             :         Assert(!bms_overlap(child_rel1->relids, child_rel2->relids));
    1478        1632 :         child_joinrelids = bms_union(child_rel1->relids, child_rel2->relids);
    1479        1632 :         appinfos = find_appinfos_by_relids(root, child_joinrelids, &nappinfos);
    1480             : 
    1481             :         /*
    1482             :          * Construct SpecialJoinInfo from parent join relations's
    1483             :          * SpecialJoinInfo.
    1484             :          */
    1485        1632 :         child_sjinfo = build_child_join_sjinfo(root, parent_sjinfo,
    1486             :                                                child_rel1->relids,
    1487             :                                                child_rel2->relids);
    1488             : 
    1489             :         /*
    1490             :          * Construct restrictions applicable to the child join from those
    1491             :          * applicable to the parent join.
    1492             :          */
    1493        1632 :         child_restrictlist =
    1494        1632 :             (List *) adjust_appendrel_attrs(root,
    1495             :                                             (Node *) parent_restrictlist,
    1496             :                                             nappinfos, appinfos);
    1497        1632 :         pfree(appinfos);
    1498             : 
    1499        1632 :         child_joinrel = joinrel->part_rels[cnt_parts];
    1500        1632 :         if (!child_joinrel)
    1501             :         {
    1502        1400 :             child_joinrel = build_child_join_rel(root, child_rel1, child_rel2,
    1503             :                                                  joinrel, child_restrictlist,
    1504             :                                                  child_sjinfo,
    1505             :                                                  child_sjinfo->jointype);
    1506        1400 :             joinrel->part_rels[cnt_parts] = child_joinrel;
    1507             :         }
    1508             : 
    1509             :         Assert(bms_equal(child_joinrel->relids, child_joinrelids));
    1510             : 
    1511        1632 :         populate_joinrel_with_paths(root, child_rel1, child_rel2,
    1512             :                                     child_joinrel, child_sjinfo,
    1513             :                                     child_restrictlist);
    1514             :     }
    1515             : }
    1516             : 
    1517             : /*
    1518             :  * Construct the SpecialJoinInfo for a child-join by translating
    1519             :  * SpecialJoinInfo for the join between parents. left_relids and right_relids
    1520             :  * are the relids of left and right side of the join respectively.
    1521             :  */
    1522             : static SpecialJoinInfo *
    1523        1632 : build_child_join_sjinfo(PlannerInfo *root, SpecialJoinInfo *parent_sjinfo,
    1524             :                         Relids left_relids, Relids right_relids)
    1525             : {
    1526        1632 :     SpecialJoinInfo *sjinfo = makeNode(SpecialJoinInfo);
    1527             :     AppendRelInfo **left_appinfos;
    1528             :     int         left_nappinfos;
    1529             :     AppendRelInfo **right_appinfos;
    1530             :     int         right_nappinfos;
    1531             : 
    1532        1632 :     memcpy(sjinfo, parent_sjinfo, sizeof(SpecialJoinInfo));
    1533        1632 :     left_appinfos = find_appinfos_by_relids(root, left_relids,
    1534             :                                             &left_nappinfos);
    1535        1632 :     right_appinfos = find_appinfos_by_relids(root, right_relids,
    1536             :                                              &right_nappinfos);
    1537             : 
    1538        1632 :     sjinfo->min_lefthand = adjust_child_relids(sjinfo->min_lefthand,
    1539             :                                                left_nappinfos, left_appinfos);
    1540        1632 :     sjinfo->min_righthand = adjust_child_relids(sjinfo->min_righthand,
    1541             :                                                 right_nappinfos,
    1542             :                                                 right_appinfos);
    1543        1632 :     sjinfo->syn_lefthand = adjust_child_relids(sjinfo->syn_lefthand,
    1544             :                                                left_nappinfos, left_appinfos);
    1545        1632 :     sjinfo->syn_righthand = adjust_child_relids(sjinfo->syn_righthand,
    1546             :                                                 right_nappinfos,
    1547             :                                                 right_appinfos);
    1548        3264 :     sjinfo->semi_rhs_exprs = (List *) adjust_appendrel_attrs(root,
    1549        1632 :                                                              (Node *) sjinfo->semi_rhs_exprs,
    1550             :                                                              right_nappinfos,
    1551             :                                                              right_appinfos);
    1552             : 
    1553        1632 :     pfree(left_appinfos);
    1554        1632 :     pfree(right_appinfos);
    1555             : 
    1556        1632 :     return sjinfo;
    1557             : }
    1558             : 
    1559             : /*
    1560             :  * Returns true if there exists an equi-join condition for each pair of
    1561             :  * partition keys from given relations being joined.
    1562             :  */
    1563             : bool
    1564         632 : have_partkey_equi_join(RelOptInfo *joinrel,
    1565             :                        RelOptInfo *rel1, RelOptInfo *rel2,
    1566             :                        JoinType jointype, List *restrictlist)
    1567             : {
    1568         632 :     PartitionScheme part_scheme = rel1->part_scheme;
    1569             :     ListCell   *lc;
    1570             :     int         cnt_pks;
    1571             :     bool        pk_has_clause[PARTITION_MAX_KEYS];
    1572             :     bool        strict_op;
    1573             : 
    1574             :     /*
    1575             :      * This function should be called when the joining relations have same
    1576             :      * partitioning scheme.
    1577             :      */
    1578             :     Assert(rel1->part_scheme == rel2->part_scheme);
    1579             :     Assert(part_scheme);
    1580             : 
    1581         632 :     memset(pk_has_clause, 0, sizeof(pk_has_clause));
    1582        1456 :     foreach(lc, restrictlist)
    1583             :     {
    1584         824 :         RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
    1585             :         OpExpr     *opexpr;
    1586             :         Expr       *expr1;
    1587             :         Expr       *expr2;
    1588             :         int         ipk1;
    1589             :         int         ipk2;
    1590             : 
    1591             :         /* If processing an outer join, only use its own join clauses. */
    1592        1280 :         if (IS_OUTER_JOIN(jointype) &&
    1593         864 :             RINFO_IS_PUSHED_DOWN(rinfo, joinrel->relids))
    1594          48 :             continue;
    1595             : 
    1596             :         /* Skip clauses which can not be used for a join. */
    1597         776 :         if (!rinfo->can_join)
    1598           4 :             continue;
    1599             : 
    1600             :         /* Skip clauses which are not equality conditions. */
    1601         772 :         if (!rinfo->mergeopfamilies && !OidIsValid(rinfo->hashjoinoperator))
    1602           4 :             continue;
    1603             : 
    1604         768 :         opexpr = castNode(OpExpr, rinfo->clause);
    1605             : 
    1606             :         /*
    1607             :          * The equi-join between partition keys is strict if equi-join between
    1608             :          * at least one partition key is using a strict operator. See
    1609             :          * explanation about outer join reordering identity 3 in
    1610             :          * optimizer/README
    1611             :          */
    1612         768 :         strict_op = op_strict(opexpr->opno);
    1613             : 
    1614             :         /* Match the operands to the relation. */
    1615        1448 :         if (bms_is_subset(rinfo->left_relids, rel1->relids) &&
    1616         680 :             bms_is_subset(rinfo->right_relids, rel2->relids))
    1617             :         {
    1618         680 :             expr1 = linitial(opexpr->args);
    1619         680 :             expr2 = lsecond(opexpr->args);
    1620             :         }
    1621         176 :         else if (bms_is_subset(rinfo->left_relids, rel2->relids) &&
    1622          88 :                  bms_is_subset(rinfo->right_relids, rel1->relids))
    1623             :         {
    1624          88 :             expr1 = lsecond(opexpr->args);
    1625          88 :             expr2 = linitial(opexpr->args);
    1626             :         }
    1627             :         else
    1628           0 :             continue;
    1629             : 
    1630             :         /*
    1631             :          * Only clauses referencing the partition keys are useful for
    1632             :          * partitionwise join.
    1633             :          */
    1634         768 :         ipk1 = match_expr_to_partition_keys(expr1, rel1, strict_op);
    1635         768 :         if (ipk1 < 0)
    1636         196 :             continue;
    1637         572 :         ipk2 = match_expr_to_partition_keys(expr2, rel2, strict_op);
    1638         572 :         if (ipk2 < 0)
    1639           0 :             continue;
    1640             : 
    1641             :         /*
    1642             :          * If the clause refers to keys at different ordinal positions, it can
    1643             :          * not be used for partitionwise join.
    1644             :          */
    1645         572 :         if (ipk1 != ipk2)
    1646           4 :             continue;
    1647             : 
    1648             :         /*
    1649             :          * The clause allows partitionwise join if only it uses the same
    1650             :          * operator family as that specified by the partition key.
    1651             :          */
    1652         568 :         if (rel1->part_scheme->strategy == PARTITION_STRATEGY_HASH)
    1653             :         {
    1654          32 :             if (!op_in_opfamily(rinfo->hashjoinoperator,
    1655          32 :                                 part_scheme->partopfamily[ipk1]))
    1656           0 :                 continue;
    1657             :         }
    1658         536 :         else if (!list_member_oid(rinfo->mergeopfamilies,
    1659         536 :                                   part_scheme->partopfamily[ipk1]))
    1660           0 :             continue;
    1661             : 
    1662             :         /* Mark the partition key as having an equi-join clause. */
    1663         568 :         pk_has_clause[ipk1] = true;
    1664             :     }
    1665             : 
    1666             :     /* Check whether every partition key has an equi-join condition. */
    1667        1200 :     for (cnt_pks = 0; cnt_pks < part_scheme->partnatts; cnt_pks++)
    1668             :     {
    1669         644 :         if (!pk_has_clause[cnt_pks])
    1670          76 :             return false;
    1671             :     }
    1672             : 
    1673         556 :     return true;
    1674             : }
    1675             : 
    1676             : /*
    1677             :  * Find the partition key from the given relation matching the given
    1678             :  * expression. If found, return the index of the partition key, else return -1.
    1679             :  */
    1680             : static int
    1681        1340 : match_expr_to_partition_keys(Expr *expr, RelOptInfo *rel, bool strict_op)
    1682             : {
    1683             :     int         cnt;
    1684             : 
    1685             :     /* This function should be called only for partitioned relations. */
    1686             :     Assert(rel->part_scheme);
    1687             : 
    1688             :     /* Remove any relabel decorations. */
    1689        2840 :     while (IsA(expr, RelabelType))
    1690         160 :         expr = (Expr *) (castNode(RelabelType, expr))->arg;
    1691             : 
    1692        1560 :     for (cnt = 0; cnt < rel->part_scheme->partnatts; cnt++)
    1693             :     {
    1694             :         ListCell   *lc;
    1695             : 
    1696             :         Assert(rel->partexprs);
    1697        1600 :         foreach(lc, rel->partexprs[cnt])
    1698             :         {
    1699        1356 :             if (equal(lfirst(lc), expr))
    1700        1120 :                 return cnt;
    1701             :         }
    1702             : 
    1703         244 :         if (!strict_op)
    1704           0 :             continue;
    1705             : 
    1706             :         /*
    1707             :          * If it's a strict equi-join a NULL partition key on one side will
    1708             :          * not join a NULL partition key on the other side. So, rows with NULL
    1709             :          * partition key from a partition on one side can not join with those
    1710             :          * from a non-matching partition on the other side. So, search the
    1711             :          * nullable partition keys as well.
    1712             :          */
    1713             :         Assert(rel->nullable_partexprs);
    1714         244 :         foreach(lc, rel->nullable_partexprs[cnt])
    1715             :         {
    1716          24 :             if (equal(lfirst(lc), expr))
    1717          24 :                 return cnt;
    1718             :         }
    1719             :     }
    1720             : 
    1721         196 :     return -1;
    1722             : }

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