#include "postgres.h"
#include "miscadmin.h"
#include "optimizer/appendinfo.h"
#include "optimizer/joininfo.h"
#include "optimizer/pathnode.h"
#include "optimizer/paths.h"
#include "partitioning/partbounds.h"
#include "utils/memutils.h"

Include dependency graph for joinrels.c:

Functions
static void	make_rels_by_clause_joins (PlannerInfo root, RelOptInfo old_rel, List *other_rels, int first_rel_idx)

static void	make_rels_by_clauseless_joins (PlannerInfo root, RelOptInfo old_rel, List *other_rels)

static bool	has_join_restriction (PlannerInfo root, RelOptInfo rel)

static bool	has_legal_joinclause (PlannerInfo root, RelOptInfo rel)

static bool	restriction_is_constant_false (List restrictlist, RelOptInfo joinrel, bool only_pushed_down)

static void	populate_joinrel_with_paths (PlannerInfo root, RelOptInfo rel1, RelOptInfo rel2, RelOptInfo joinrel, SpecialJoinInfo sjinfo, List restrictlist)

static void	try_partitionwise_join (PlannerInfo root, RelOptInfo rel1, RelOptInfo rel2, RelOptInfo joinrel, SpecialJoinInfo parent_sjinfo, List parent_restrictlist)

static SpecialJoinInfo *	build_child_join_sjinfo (PlannerInfo root, SpecialJoinInfo parent_sjinfo, Relids left_relids, Relids right_relids)

static void	compute_partition_bounds (PlannerInfo root, RelOptInfo rel1, RelOptInfo rel2, RelOptInfo joinrel, SpecialJoinInfo parent_sjinfo, List parts1, List *parts2)

static void	get_matching_part_pairs (PlannerInfo root, RelOptInfo joinrel, RelOptInfo rel1, RelOptInfo rel2, List parts1, List parts2)

void	join_search_one_level (PlannerInfo *root, int level)

static bool	join_is_legal (PlannerInfo root, RelOptInfo rel1, RelOptInfo rel2, Relids joinrelids, SpecialJoinInfo sjinfo_p, bool reversed_p)

RelOptInfo *	make_join_rel (PlannerInfo root, RelOptInfo rel1, RelOptInfo *rel2)

Relids	add_outer_joins_to_relids (PlannerInfo root, Relids input_relids, SpecialJoinInfo sjinfo, List **pushed_down_joins)

bool	have_join_order_restriction (PlannerInfo root, RelOptInfo rel1, RelOptInfo *rel2)

bool	have_dangerous_phv (PlannerInfo *root, Relids outer_relids, Relids inner_params)

bool	is_dummy_rel (RelOptInfo *rel)

void	mark_dummy_rel (RelOptInfo *rel)

Function Documentation

◆ add_outer_joins_to_relids()

Relids add_outer_joins_to_relids	(	PlannerInfo *	root,
		Relids	input_relids,
		SpecialJoinInfo *	sjinfo,
		List **	pushed_down_joins
	)

Definition at line 783 of file joinrels.c.

 {
     /* Nothing to do if this isn't an outer join with an assigned relid. */
     if (sjinfo == NULL || sjinfo->ojrelid == 0)
         return input_relids;
  
     /*
      * If it's not a left join, we have no rules that would permit executing
      * it in non-syntactic order, so just form the syntactic relid set.  (This
      * is just a quick-exit test; we'd come to the same conclusion anyway,
      * since its commute_below_l and commute_above_l sets must be empty.)
      */
     if (sjinfo->jointype != JOIN_LEFT)
         return bms_add_member(input_relids, sjinfo->ojrelid);
  
     /*
      * We cannot add the OJ relid if this join has been pushed into the RHS of
      * a syntactically-lower left join per OJ identity 3.  (If it has, then we
      * cannot claim that its outputs represent the final state of its RHS.)
      * There will not be any other OJs that can be added either, so we're
      * done.
      */
     if (!bms_is_subset(sjinfo->commute_below_l, input_relids))
         return input_relids;
  
     /* OK to add OJ's own relid */
     input_relids = bms_add_member(input_relids, sjinfo->ojrelid);
  
     /*
      * Contrariwise, if we are now forming the final result of such a commuted
      * pair of OJs, it's time to add the relid(s) of the pushed-down join(s).
      * We can skip this if this join was never a candidate to be pushed up.
      */
     if (sjinfo->commute_above_l)
     {
         Relids      commute_above_rels = bms_copy(sjinfo->commute_above_l);
         ListCell   *lc;
  
         /*
          * The current join could complete the nulling of more than one
          * pushed-down join, so we have to examine all the SpecialJoinInfos.
          * Because join_info_list was built in bottom-up order, it's
          * sufficient to traverse it once: an ojrelid we add in one loop
          * iteration would not have affected decisions of earlier iterations.
          */
         foreach(lc, root->join_info_list)
         {
             SpecialJoinInfo *othersj = (SpecialJoinInfo *) lfirst(lc);
  
             if (othersj == sjinfo ||
                 othersj->ojrelid == 0 || othersj->jointype != JOIN_LEFT)
                 continue;       /* definitely not interesting */
  
             if (!bms_is_member(othersj->ojrelid, commute_above_rels))
                 continue;
  
             /* Add it if not already present but conditions now satisfied */
             if (!bms_is_member(othersj->ojrelid, input_relids) &&
                 bms_is_subset(othersj->min_lefthand, input_relids) &&
                 bms_is_subset(othersj->min_righthand, input_relids) &&
                 bms_is_subset(othersj->commute_below_l, input_relids))
             {
                 input_relids = bms_add_member(input_relids, othersj->ojrelid);
                 /* report such pushed down outer joins, if asked */
                 if (pushed_down_joins != NULL)
                     *pushed_down_joins = lappend(*pushed_down_joins, othersj);
  
                 /*
                  * We must also check any joins that othersj potentially
                  * commutes with.  They likewise must appear later in
                  * join_info_list than othersj itself, so we can visit them
                  * later in this loop.
                  */
                 commute_above_rels = bms_add_members(commute_above_rels,
                                                      othersj->commute_above_l);
             }
         }
     }
  
     return input_relids;
 }

References bms_add_member(), bms_add_members(), bms_copy(), bms_is_member(), bms_is_subset(), SpecialJoinInfo::commute_above_l, SpecialJoinInfo::commute_below_l, PlannerInfo::join_info_list, JOIN_LEFT, SpecialJoinInfo::jointype, lappend(), lfirst, SpecialJoinInfo::min_lefthand, SpecialJoinInfo::min_righthand, and SpecialJoinInfo::ojrelid.

Referenced by generate_join_implied_equalities(), and make_join_rel().

◆ build_child_join_sjinfo()

static SpecialJoinInfo * build_child_join_sjinfo	(	PlannerInfo *	root,
		SpecialJoinInfo *	parent_sjinfo,
		Relids	left_relids,
		Relids	right_relids
	)

static

Definition at line 1671 of file joinrels.c.

 {
     SpecialJoinInfo *sjinfo = makeNode(SpecialJoinInfo);
     AppendRelInfo **left_appinfos;
     int         left_nappinfos;
     AppendRelInfo **right_appinfos;
     int         right_nappinfos;
  
     memcpy(sjinfo, parent_sjinfo, sizeof(SpecialJoinInfo));
     left_appinfos = find_appinfos_by_relids(root, left_relids,
                                             &left_nappinfos);
     right_appinfos = find_appinfos_by_relids(root, right_relids,
                                              &right_nappinfos);
  
     sjinfo->min_lefthand = adjust_child_relids(sjinfo->min_lefthand,
                                                left_nappinfos, left_appinfos);
     sjinfo->min_righthand = adjust_child_relids(sjinfo->min_righthand,
                                                 right_nappinfos,
                                                 right_appinfos);
     sjinfo->syn_lefthand = adjust_child_relids(sjinfo->syn_lefthand,
                                                left_nappinfos, left_appinfos);
     sjinfo->syn_righthand = adjust_child_relids(sjinfo->syn_righthand,
                                                 right_nappinfos,
                                                 right_appinfos);
     /* outer-join relids need no adjustment */
     sjinfo->semi_rhs_exprs = (List *) adjust_appendrel_attrs(root,
                                                              (Node *) sjinfo->semi_rhs_exprs,
                                                              right_nappinfos,
                                                              right_appinfos);
  
     pfree(left_appinfos);
     pfree(right_appinfos);
  
     return sjinfo;
 }

References adjust_appendrel_attrs(), adjust_child_relids(), find_appinfos_by_relids(), makeNode, SpecialJoinInfo::min_lefthand, SpecialJoinInfo::min_righthand, pfree(), SpecialJoinInfo::semi_rhs_exprs, SpecialJoinInfo::syn_lefthand, and SpecialJoinInfo::syn_righthand.

Referenced by try_partitionwise_join().

◆ compute_partition_bounds()

static void compute_partition_bounds	(	PlannerInfo *	root,
		RelOptInfo *	rel1,
		RelOptInfo *	rel2,
		RelOptInfo *	joinrel,
		SpecialJoinInfo *	parent_sjinfo,
		List **	parts1,
		List **	parts2
	)

static

Definition at line 1713 of file joinrels.c.

 {
     /*
      * If we don't have the partition bounds for the join rel yet, try to
      * compute those along with pairs of partitions to be joined.
      */
     if (joinrel->nparts == -1)
     {
         PartitionScheme part_scheme = joinrel->part_scheme;
         PartitionBoundInfo boundinfo = NULL;
         int         nparts = 0;
  
         Assert(joinrel->boundinfo == NULL);
         Assert(joinrel->part_rels == NULL);
  
         /*
          * See if the partition bounds for inputs are exactly the same, in
          * which case we don't need to work hard: the join rel will have the
          * same partition bounds as inputs, and the partitions with the same
          * cardinal positions will form the pairs.
          *
          * Note: even in cases where one or both inputs have merged bounds, it
          * would be possible for both the bounds to be exactly the same, but
          * it seems unlikely to be worth the cycles to check.
          */
         if (!rel1->partbounds_merged &&
             !rel2->partbounds_merged &&
             rel1->nparts == rel2->nparts &&
             partition_bounds_equal(part_scheme->partnatts,
                                    part_scheme->parttyplen,
                                    part_scheme->parttypbyval,
                                    rel1->boundinfo, rel2->boundinfo))
         {
             boundinfo = rel1->boundinfo;
             nparts = rel1->nparts;
         }
         else
         {
             /* Try merging the partition bounds for inputs. */
             boundinfo = partition_bounds_merge(part_scheme->partnatts,
                                                part_scheme->partsupfunc,
                                                part_scheme->partcollation,
                                                rel1, rel2,
                                                parent_sjinfo->jointype,
                                                parts1, parts2);
             if (boundinfo == NULL)
             {
                 joinrel->nparts = 0;
                 return;
             }
             nparts = list_length(*parts1);
             joinrel->partbounds_merged = true;
         }
  
         Assert(nparts > 0);
         joinrel->boundinfo = boundinfo;
         joinrel->nparts = nparts;
         joinrel->part_rels =
             (RelOptInfo **) palloc0(sizeof(RelOptInfo *) * nparts);
     }
     else
     {
         Assert(joinrel->nparts > 0);
         Assert(joinrel->boundinfo);
         Assert(joinrel->part_rels);
  
         /*
          * If the join rel's partbounds_merged flag is true, it means inputs
          * are not guaranteed to have the same partition bounds, therefore we
          * can't assume that the partitions at the same cardinal positions
          * form the pairs; let get_matching_part_pairs() generate the pairs.
          * Otherwise, nothing to do since we can assume that.
          */
         if (joinrel->partbounds_merged)
         {
             get_matching_part_pairs(root, joinrel, rel1, rel2,
                                     parts1, parts2);
             Assert(list_length(*parts1) == joinrel->nparts);
             Assert(list_length(*parts2) == joinrel->nparts);
         }
     }
 }

References Assert(), get_matching_part_pairs(), SpecialJoinInfo::jointype, list_length(), RelOptInfo::nparts, palloc0(), RelOptInfo::partbounds_merged, PartitionSchemeData::partcollation, partition_bounds_equal(), partition_bounds_merge(), PartitionSchemeData::partnatts, PartitionSchemeData::partsupfunc, PartitionSchemeData::parttypbyval, and PartitionSchemeData::parttyplen.

Referenced by try_partitionwise_join().

◆ get_matching_part_pairs()

static void get_matching_part_pairs	(	PlannerInfo *	root,
		RelOptInfo *	joinrel,
		RelOptInfo *	rel1,
		RelOptInfo *	rel2,
		List **	parts1,
		List **	parts2
	)

static

Definition at line 1804 of file joinrels.c.

 {
     bool        rel1_is_simple = IS_SIMPLE_REL(rel1);
     bool        rel2_is_simple = IS_SIMPLE_REL(rel2);
     int         cnt_parts;
  
     *parts1 = NIL;
     *parts2 = NIL;
  
     for (cnt_parts = 0; cnt_parts < joinrel->nparts; cnt_parts++)
     {
         RelOptInfo *child_joinrel = joinrel->part_rels[cnt_parts];
         RelOptInfo *child_rel1;
         RelOptInfo *child_rel2;
         Relids      child_relids1;
         Relids      child_relids2;
  
         /*
          * If this segment of the join is empty, it means that this segment
          * was ignored when previously creating child-join paths for it in
          * try_partitionwise_join() as it would not contribute to the join
          * result, due to one or both inputs being empty; add NULL to each of
          * the given lists so that this segment will be ignored again in that
          * function.
          */
         if (!child_joinrel)
         {
             *parts1 = lappend(*parts1, NULL);
             *parts2 = lappend(*parts2, NULL);
             continue;
         }
  
         /*
          * Get a relids set of partition(s) involved in this join segment that
          * are from the rel1 side.
          */
         child_relids1 = bms_intersect(child_joinrel->relids,
                                       rel1->all_partrels);
         Assert(bms_num_members(child_relids1) == bms_num_members(rel1->relids));
  
         /*
          * Get a child rel for rel1 with the relids.  Note that we should have
          * the child rel even if rel1 is a join rel, because in that case the
          * partitions specified in the relids would have matching/overlapping
          * boundaries, so the specified partitions should be considered as
          * ones to be joined when planning partitionwise joins of rel1,
          * meaning that the child rel would have been built by the time we get
          * here.
          */
         if (rel1_is_simple)
         {
             int         varno = bms_singleton_member(child_relids1);
  
             child_rel1 = find_base_rel(root, varno);
         }
         else
             child_rel1 = find_join_rel(root, child_relids1);
         Assert(child_rel1);
  
         /*
          * Get a relids set of partition(s) involved in this join segment that
          * are from the rel2 side.
          */
         child_relids2 = bms_intersect(child_joinrel->relids,
                                       rel2->all_partrels);
         Assert(bms_num_members(child_relids2) == bms_num_members(rel2->relids));
  
         /*
          * Get a child rel for rel2 with the relids.  See above comments.
          */
         if (rel2_is_simple)
         {
             int         varno = bms_singleton_member(child_relids2);
  
             child_rel2 = find_base_rel(root, varno);
         }
         else
             child_rel2 = find_join_rel(root, child_relids2);
         Assert(child_rel2);
  
         /*
          * The join of rel1 and rel2 is legal, so is the join of the child
          * rels obtained above; add them to the given lists as a join pair
          * producing this join segment.
          */
         *parts1 = lappend(*parts1, child_rel1);
         *parts2 = lappend(*parts2, child_rel2);
     }
 }

References RelOptInfo::all_partrels, Assert(), bms_intersect(), bms_num_members(), bms_singleton_member(), find_base_rel(), find_join_rel(), IS_SIMPLE_REL, lappend(), NIL, RelOptInfo::nparts, and RelOptInfo::relids.

Referenced by compute_partition_bounds().

◆ has_join_restriction()

static bool has_join_restriction	(	PlannerInfo *	root,
		RelOptInfo *	rel
	)

static

Definition at line 1166 of file joinrels.c.

 {
     ListCell   *l;
  
     if (rel->lateral_relids != NULL || rel->lateral_referencers != NULL)
         return true;
  
     foreach(l, root->placeholder_list)
     {
         PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(l);
  
         if (bms_is_subset(rel->relids, phinfo->ph_eval_at) &&
             !bms_equal(rel->relids, phinfo->ph_eval_at))
             return true;
     }
  
     foreach(l, root->join_info_list)
     {
         SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(l);
  
         /* ignore full joins --- other mechanisms preserve their ordering */
         if (sjinfo->jointype == JOIN_FULL)
             continue;
  
         /* ignore if SJ is already contained in rel */
         if (bms_is_subset(sjinfo->min_lefthand, rel->relids) &&
             bms_is_subset(sjinfo->min_righthand, rel->relids))
             continue;
  
         /* restricted if it overlaps LHS or RHS, but doesn't contain SJ */
         if (bms_overlap(sjinfo->min_lefthand, rel->relids) ||
             bms_overlap(sjinfo->min_righthand, rel->relids))
             return true;
     }
  
     return false;
 }

References bms_equal(), bms_is_subset(), bms_overlap(), JOIN_FULL, PlannerInfo::join_info_list, SpecialJoinInfo::jointype, RelOptInfo::lateral_referencers, RelOptInfo::lateral_relids, lfirst, SpecialJoinInfo::min_lefthand, SpecialJoinInfo::min_righthand, PlaceHolderInfo::ph_eval_at, PlannerInfo::placeholder_list, and RelOptInfo::relids.

Referenced by join_search_one_level().

◆ has_legal_joinclause()

static bool has_legal_joinclause	(	PlannerInfo *	root,
		RelOptInfo *	rel
	)

static

Definition at line 1222 of file joinrels.c.

 {
     ListCell   *lc;
  
     foreach(lc, root->initial_rels)
     {
         RelOptInfo *rel2 = (RelOptInfo *) lfirst(lc);
  
         /* ignore rels that are already in "rel" */
         if (bms_overlap(rel->relids, rel2->relids))
             continue;
  
         if (have_relevant_joinclause(root, rel, rel2))
         {
             Relids      joinrelids;
             SpecialJoinInfo *sjinfo;
             bool        reversed;
  
             /* join_is_legal needs relids of the union */
             joinrelids = bms_union(rel->relids, rel2->relids);
  
             if (join_is_legal(root, rel, rel2, joinrelids,
                               &sjinfo, &reversed))
             {
                 /* Yes, this will work */
                 bms_free(joinrelids);
                 return true;
             }
  
             bms_free(joinrelids);
         }
     }
  
     return false;
 }

References bms_free(), bms_overlap(), bms_union(), have_relevant_joinclause(), join_is_legal(), lfirst, and RelOptInfo::relids.

Referenced by have_join_order_restriction().

◆ have_dangerous_phv()

bool have_dangerous_phv	(	PlannerInfo *	root,
		Relids	outer_relids,
		Relids	inner_params
	)

Definition at line 1286 of file joinrels.c.

 {
     ListCell   *lc;
  
     foreach(lc, root->placeholder_list)
     {
         PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(lc);
  
         if (!bms_is_subset(phinfo->ph_eval_at, inner_params))
             continue;           /* ignore, could not be a nestloop param */
         if (!bms_overlap(phinfo->ph_eval_at, outer_relids))
             continue;           /* ignore, not relevant to this join */
         if (bms_is_subset(phinfo->ph_eval_at, outer_relids))
             continue;           /* safe, it can be eval'd within outerrel */
         /* Otherwise, it's potentially unsafe, so reject the join */
         return true;
     }
  
     /* OK to perform the join */
     return false;
 }

References bms_is_subset(), bms_overlap(), lfirst, PlaceHolderInfo::ph_eval_at, and PlannerInfo::placeholder_list.

Referenced by join_is_legal(), and try_nestloop_path().

◆ have_join_order_restriction()

bool have_join_order_restriction	(	PlannerInfo *	root,
		RelOptInfo *	rel1,
		RelOptInfo *	rel2
	)

Definition at line 1053 of file joinrels.c.

 {
     bool        result = false;
     ListCell   *l;
  
     /*
      * If either side has a direct lateral reference to the other, attempt the
      * join regardless of outer-join considerations.
      */
     if (bms_overlap(rel1->relids, rel2->direct_lateral_relids) ||
         bms_overlap(rel2->relids, rel1->direct_lateral_relids))
         return true;
  
     /*
      * Likewise, if both rels are needed to compute some PlaceHolderVar,
      * attempt the join regardless of outer-join considerations.  (This is not
      * very desirable, because a PHV with a large eval_at set will cause a lot
      * of probably-useless joins to be considered, but failing to do this can
      * cause us to fail to construct a plan at all.)
      */
     foreach(l, root->placeholder_list)
     {
         PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(l);
  
         if (bms_is_subset(rel1->relids, phinfo->ph_eval_at) &&
             bms_is_subset(rel2->relids, phinfo->ph_eval_at))
             return true;
     }
  
     /*
      * It's possible that the rels correspond to the left and right sides of a
      * degenerate outer join, that is, one with no joinclause mentioning the
      * non-nullable side; in which case we should force the join to occur.
      *
      * Also, the two rels could represent a clauseless join that has to be
      * completed to build up the LHS or RHS of an outer join.
      */
     foreach(l, root->join_info_list)
     {
         SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(l);
  
         /* ignore full joins --- other mechanisms handle them */
         if (sjinfo->jointype == JOIN_FULL)
             continue;
  
         /* Can we perform the SJ with these rels? */
         if (bms_is_subset(sjinfo->min_lefthand, rel1->relids) &&
             bms_is_subset(sjinfo->min_righthand, rel2->relids))
         {
             result = true;
             break;
         }
         if (bms_is_subset(sjinfo->min_lefthand, rel2->relids) &&
             bms_is_subset(sjinfo->min_righthand, rel1->relids))
         {
             result = true;
             break;
         }
  
         /*
          * Might we need to join these rels to complete the RHS?  We have to
          * use "overlap" tests since either rel might include a lower SJ that
          * has been proven to commute with this one.
          */
         if (bms_overlap(sjinfo->min_righthand, rel1->relids) &&
             bms_overlap(sjinfo->min_righthand, rel2->relids))
         {
             result = true;
             break;
         }
  
         /* Likewise for the LHS. */
         if (bms_overlap(sjinfo->min_lefthand, rel1->relids) &&
             bms_overlap(sjinfo->min_lefthand, rel2->relids))
         {
             result = true;
             break;
         }
     }
  
     /*
      * We do not force the join to occur if either input rel can legally be
      * joined to anything else using joinclauses.  This essentially means that
      * clauseless bushy joins are put off as long as possible. The reason is
      * that when there is a join order restriction high up in the join tree
      * (that is, with many rels inside the LHS or RHS), we would otherwise
      * expend lots of effort considering very stupid join combinations within
      * its LHS or RHS.
      */
     if (result)
     {
         if (has_legal_joinclause(root, rel1) ||
             has_legal_joinclause(root, rel2))
             result = false;
     }
  
     return result;
 }

References bms_is_subset(), bms_overlap(), RelOptInfo::direct_lateral_relids, has_legal_joinclause(), JOIN_FULL, PlannerInfo::join_info_list, SpecialJoinInfo::jointype, lfirst, SpecialJoinInfo::min_lefthand, SpecialJoinInfo::min_righthand, PlaceHolderInfo::ph_eval_at, PlannerInfo::placeholder_list, and RelOptInfo::relids.

Referenced by desirable_join(), join_search_one_level(), and make_rels_by_clause_joins().

◆ is_dummy_rel()

bool is_dummy_rel ( RelOptInfo * rel )

Definition at line 1314 of file joinrels.c.

 {
     Path       *path;
  
     /*
      * A rel that is known dummy will have just one path that is a childless
      * Append.  (Even if somehow it has more paths, a childless Append will
      * have cost zero and hence should be at the front of the pathlist.)
      */
     if (rel->pathlist == NIL)
         return false;
     path = (Path *) linitial(rel->pathlist);
  
     /*
      * Initially, a dummy path will just be a childless Append.  But in later
      * planning stages we might stick a ProjectSetPath and/or ProjectionPath
      * on top, since Append can't project.  Rather than make assumptions about
      * which combinations can occur, just descend through whatever we find.
      */
     for (;;)
     {
         if (IsA(path, ProjectionPath))
             path = ((ProjectionPath *) path)->subpath;
         else if (IsA(path, ProjectSetPath))
             path = ((ProjectSetPath *) path)->subpath;
         else
             break;
     }
     if (IS_DUMMY_APPEND(path))
         return true;
     return false;
 }

References IS_DUMMY_APPEND, IsA, linitial, NIL, RelOptInfo::pathlist, and subpath().

Referenced by make_join_rel(), mark_dummy_rel(), and populate_joinrel_with_paths().

◆ join_is_legal()

static bool join_is_legal	(	PlannerInfo *	root,
		RelOptInfo *	rel1,
		RelOptInfo *	rel2,
		Relids	joinrelids,
		SpecialJoinInfo **	sjinfo_p,
		bool *	reversed_p
	)

static

Definition at line 348 of file joinrels.c.

 {
     SpecialJoinInfo *match_sjinfo;
     bool        reversed;
     bool        unique_ified;
     bool        must_be_leftjoin;
     ListCell   *l;
  
     /*
      * Ensure output params are set on failure return.  This is just to
      * suppress uninitialized-variable warnings from overly anal compilers.
      */
     *sjinfo_p = NULL;
     *reversed_p = false;
  
     /*
      * If we have any special joins, the proposed join might be illegal; and
      * in any case we have to determine its join type.  Scan the join info
      * list for matches and conflicts.
      */
     match_sjinfo = NULL;
     reversed = false;
     unique_ified = false;
     must_be_leftjoin = false;
  
     foreach(l, root->join_info_list)
     {
         SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(l);
  
         /*
          * This special join is not relevant unless its RHS overlaps the
          * proposed join.  (Check this first as a fast path for dismissing
          * most irrelevant SJs quickly.)
          */
         if (!bms_overlap(sjinfo->min_righthand, joinrelids))
             continue;
  
         /*
          * Also, not relevant if proposed join is fully contained within RHS
          * (ie, we're still building up the RHS).
          */
         if (bms_is_subset(joinrelids, sjinfo->min_righthand))
             continue;
  
         /*
          * Also, not relevant if SJ is already done within either input.
          */
         if (bms_is_subset(sjinfo->min_lefthand, rel1->relids) &&
             bms_is_subset(sjinfo->min_righthand, rel1->relids))
             continue;
         if (bms_is_subset(sjinfo->min_lefthand, rel2->relids) &&
             bms_is_subset(sjinfo->min_righthand, rel2->relids))
             continue;
  
         /*
          * If it's a semijoin and we already joined the RHS to any other rels
          * within either input, then we must have unique-ified the RHS at that
          * point (see below).  Therefore the semijoin is no longer relevant in
          * this join path.
          */
         if (sjinfo->jointype == JOIN_SEMI)
         {
             if (bms_is_subset(sjinfo->syn_righthand, rel1->relids) &&
                 !bms_equal(sjinfo->syn_righthand, rel1->relids))
                 continue;
             if (bms_is_subset(sjinfo->syn_righthand, rel2->relids) &&
                 !bms_equal(sjinfo->syn_righthand, rel2->relids))
                 continue;
         }
  
         /*
          * If one input contains min_lefthand and the other contains
          * min_righthand, then we can perform the SJ at this join.
          *
          * Reject if we get matches to more than one SJ; that implies we're
          * considering something that's not really valid.
          */
         if (bms_is_subset(sjinfo->min_lefthand, rel1->relids) &&
             bms_is_subset(sjinfo->min_righthand, rel2->relids))
         {
             if (match_sjinfo)
                 return false;   /* invalid join path */
             match_sjinfo = sjinfo;
             reversed = false;
         }
         else if (bms_is_subset(sjinfo->min_lefthand, rel2->relids) &&
                  bms_is_subset(sjinfo->min_righthand, rel1->relids))
         {
             if (match_sjinfo)
                 return false;   /* invalid join path */
             match_sjinfo = sjinfo;
             reversed = true;
         }
         else if (sjinfo->jointype == JOIN_SEMI &&
                  bms_equal(sjinfo->syn_righthand, rel2->relids) &&
                  create_unique_path(root, rel2, rel2->cheapest_total_path,
                                     sjinfo) != NULL)
         {
             /*----------
              * For a semijoin, we can join the RHS to anything else by
              * unique-ifying the RHS (if the RHS can be unique-ified).
              * We will only get here if we have the full RHS but less
              * than min_lefthand on the LHS.
              *
              * The reason to consider such a join path is exemplified by
              *  SELECT ... FROM a,b WHERE (a.x,b.y) IN (SELECT c1,c2 FROM c)
              * If we insist on doing this as a semijoin we will first have
              * to form the cartesian product of A*B.  But if we unique-ify
              * C then the semijoin becomes a plain innerjoin and we can join
              * in any order, eg C to A and then to B.  When C is much smaller
              * than A and B this can be a huge win.  So we allow C to be
              * joined to just A or just B here, and then make_join_rel has
              * to handle the case properly.
              *
              * Note that actually we'll allow unique-ified C to be joined to
              * some other relation D here, too.  That is legal, if usually not
              * very sane, and this routine is only concerned with legality not
              * with whether the join is good strategy.
              *----------
              */
             if (match_sjinfo)
                 return false;   /* invalid join path */
             match_sjinfo = sjinfo;
             reversed = false;
             unique_ified = true;
         }
         else if (sjinfo->jointype == JOIN_SEMI &&
                  bms_equal(sjinfo->syn_righthand, rel1->relids) &&
                  create_unique_path(root, rel1, rel1->cheapest_total_path,
                                     sjinfo) != NULL)
         {
             /* Reversed semijoin case */
             if (match_sjinfo)
                 return false;   /* invalid join path */
             match_sjinfo = sjinfo;
             reversed = true;
             unique_ified = true;
         }
         else
         {
             /*
              * Otherwise, the proposed join overlaps the RHS but isn't a valid
              * implementation of this SJ.  But don't panic quite yet: the RHS
              * violation might have occurred previously, in one or both input
              * relations, in which case we must have previously decided that
              * it was OK to commute some other SJ with this one.  If we need
              * to perform this join to finish building up the RHS, rejecting
              * it could lead to not finding any plan at all.  (This can occur
              * because of the heuristics elsewhere in this file that postpone
              * clauseless joins: we might not consider doing a clauseless join
              * within the RHS until after we've performed other, validly
              * commutable SJs with one or both sides of the clauseless join.)
              * This consideration boils down to the rule that if both inputs
              * overlap the RHS, we can allow the join --- they are either
              * fully within the RHS, or represent previously-allowed joins to
              * rels outside it.
              */
             if (bms_overlap(rel1->relids, sjinfo->min_righthand) &&
                 bms_overlap(rel2->relids, sjinfo->min_righthand))
                 continue;       /* assume valid previous violation of RHS */
  
             /*
              * The proposed join could still be legal, but only if we're
              * allowed to associate it into the RHS of this SJ.  That means
              * this SJ must be a LEFT join (not SEMI or ANTI, and certainly
              * not FULL) and the proposed join must not overlap the LHS.
              */
             if (sjinfo->jointype != JOIN_LEFT ||
                 bms_overlap(joinrelids, sjinfo->min_lefthand))
                 return false;   /* invalid join path */
  
             /*
              * To be valid, the proposed join must be a LEFT join; otherwise
              * it can't associate into this SJ's RHS.  But we may not yet have
              * found the SpecialJoinInfo matching the proposed join, so we
              * can't test that yet.  Remember the requirement for later.
              */
             must_be_leftjoin = true;
         }
     }
  
     /*
      * Fail if violated any SJ's RHS and didn't match to a LEFT SJ: the
      * proposed join can't associate into an SJ's RHS.
      *
      * Also, fail if the proposed join's predicate isn't strict; we're
      * essentially checking to see if we can apply outer-join identity 3, and
      * that's a requirement.  (This check may be redundant with checks in
      * make_outerjoininfo, but I'm not quite sure, and it's cheap to test.)
      */
     if (must_be_leftjoin &&
         (match_sjinfo == NULL ||
          match_sjinfo->jointype != JOIN_LEFT ||
          !match_sjinfo->lhs_strict))
         return false;           /* invalid join path */
  
     /*
      * We also have to check for constraints imposed by LATERAL references.
      */
     if (root->hasLateralRTEs)
     {
         bool        lateral_fwd;
         bool        lateral_rev;
         Relids      join_lateral_rels;
  
         /*
          * The proposed rels could each contain lateral references to the
          * other, in which case the join is impossible.  If there are lateral
          * references in just one direction, then the join has to be done with
          * a nestloop with the lateral referencer on the inside.  If the join
          * matches an SJ that cannot be implemented by such a nestloop, the
          * join is impossible.
          *
          * Also, if the lateral reference is only indirect, we should reject
          * the join; whatever rel(s) the reference chain goes through must be
          * joined to first.
          *
          * Another case that might keep us from building a valid plan is the
          * implementation restriction described by have_dangerous_phv().
          */
         lateral_fwd = bms_overlap(rel1->relids, rel2->lateral_relids);
         lateral_rev = bms_overlap(rel2->relids, rel1->lateral_relids);
         if (lateral_fwd && lateral_rev)
             return false;       /* have lateral refs in both directions */
         if (lateral_fwd)
         {
             /* has to be implemented as nestloop with rel1 on left */
             if (match_sjinfo &&
                 (reversed ||
                  unique_ified ||
                  match_sjinfo->jointype == JOIN_FULL))
                 return false;   /* not implementable as nestloop */
             /* check there is a direct reference from rel2 to rel1 */
             if (!bms_overlap(rel1->relids, rel2->direct_lateral_relids))
                 return false;   /* only indirect refs, so reject */
             /* check we won't have a dangerous PHV */
             if (have_dangerous_phv(root, rel1->relids, rel2->lateral_relids))
                 return false;   /* might be unable to handle required PHV */
         }
         else if (lateral_rev)
         {
             /* has to be implemented as nestloop with rel2 on left */
             if (match_sjinfo &&
                 (!reversed ||
                  unique_ified ||
                  match_sjinfo->jointype == JOIN_FULL))
                 return false;   /* not implementable as nestloop */
             /* check there is a direct reference from rel1 to rel2 */
             if (!bms_overlap(rel2->relids, rel1->direct_lateral_relids))
                 return false;   /* only indirect refs, so reject */
             /* check we won't have a dangerous PHV */
             if (have_dangerous_phv(root, rel2->relids, rel1->lateral_relids))
                 return false;   /* might be unable to handle required PHV */
         }
  
         /*
          * LATERAL references could also cause problems later on if we accept
          * this join: if the join's minimum parameterization includes any rels
          * that would have to be on the inside of an outer join with this join
          * rel, then it's never going to be possible to build the complete
          * query using this join.  We should reject this join not only because
          * it'll save work, but because if we don't, the clauseless-join
          * heuristics might think that legality of this join means that some
          * other join rel need not be formed, and that could lead to failure
          * to find any plan at all.  We have to consider not only rels that
          * are directly on the inner side of an OJ with the joinrel, but also
          * ones that are indirectly so, so search to find all such rels.
          */
         join_lateral_rels = min_join_parameterization(root, joinrelids,
                                                       rel1, rel2);
         if (join_lateral_rels)
         {
             Relids      join_plus_rhs = bms_copy(joinrelids);
             bool        more;
  
             do
             {
                 more = false;
                 foreach(l, root->join_info_list)
                 {
                     SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(l);
  
                     /* ignore full joins --- their ordering is predetermined */
                     if (sjinfo->jointype == JOIN_FULL)
                         continue;
  
                     if (bms_overlap(sjinfo->min_lefthand, join_plus_rhs) &&
                         !bms_is_subset(sjinfo->min_righthand, join_plus_rhs))
                     {
                         join_plus_rhs = bms_add_members(join_plus_rhs,
                                                         sjinfo->min_righthand);
                         more = true;
                     }
                 }
             } while (more);
             if (bms_overlap(join_plus_rhs, join_lateral_rels))
                 return false;   /* will not be able to join to some RHS rel */
         }
     }
  
     /* Otherwise, it's a valid join */
     *sjinfo_p = match_sjinfo;
     *reversed_p = reversed;
     return true;
 }

References bms_add_members(), bms_copy(), bms_equal(), bms_is_subset(), bms_overlap(), RelOptInfo::cheapest_total_path, create_unique_path(), RelOptInfo::direct_lateral_relids, PlannerInfo::hasLateralRTEs, have_dangerous_phv(), JOIN_FULL, PlannerInfo::join_info_list, JOIN_LEFT, JOIN_SEMI, SpecialJoinInfo::jointype, RelOptInfo::lateral_relids, lfirst, SpecialJoinInfo::lhs_strict, min_join_parameterization(), SpecialJoinInfo::min_lefthand, SpecialJoinInfo::min_righthand, RelOptInfo::relids, and SpecialJoinInfo::syn_righthand.

Referenced by has_legal_joinclause(), and make_join_rel().

◆ join_search_one_level()

void join_search_one_level	(	PlannerInfo *	root,
		int	level
	)

Definition at line 71 of file joinrels.c.

 {
     List      **joinrels = root->join_rel_level;
     ListCell   *r;
     int         k;
  
     Assert(joinrels[level] == NIL);
  
     /* Set join_cur_level so that new joinrels are added to proper list */
     root->join_cur_level = level;
  
     /*
      * First, consider left-sided and right-sided plans, in which rels of
      * exactly level-1 member relations are joined against initial relations.
      * We prefer to join using join clauses, but if we find a rel of level-1
      * members that has no join clauses, we will generate Cartesian-product
      * joins against all initial rels not already contained in it.
      */
     foreach(r, joinrels[level - 1])
     {
         RelOptInfo *old_rel = (RelOptInfo *) lfirst(r);
  
         if (old_rel->joininfo != NIL || old_rel->has_eclass_joins ||
             has_join_restriction(root, old_rel))
         {
             int         first_rel;
  
             /*
              * There are join clauses or join order restrictions relevant to
              * this rel, so consider joins between this rel and (only) those
              * initial rels it is linked to by a clause or restriction.
              *
              * At level 2 this condition is symmetric, so there is no need to
              * look at initial rels before this one in the list; we already
              * considered such joins when we were at the earlier rel.  (The
              * mirror-image joins are handled automatically by make_join_rel.)
              * In later passes (level > 2), we join rels of the previous level
              * to each initial rel they don't already include but have a join
              * clause or restriction with.
              */
             if (level == 2)     /* consider remaining initial rels */
                 first_rel = foreach_current_index(r) + 1;
             else
                 first_rel = 0;
  
             make_rels_by_clause_joins(root, old_rel, joinrels[1], first_rel);
         }
         else
         {
             /*
              * Oops, we have a relation that is not joined to any other
              * relation, either directly or by join-order restrictions.
              * Cartesian product time.
              *
              * We consider a cartesian product with each not-already-included
              * initial rel, whether it has other join clauses or not.  At
              * level 2, if there are two or more clauseless initial rels, we
              * will redundantly consider joining them in both directions; but
              * such cases aren't common enough to justify adding complexity to
              * avoid the duplicated effort.
              */
             make_rels_by_clauseless_joins(root,
                                           old_rel,
                                           joinrels[1]);
         }
     }
  
     /*
      * Now, consider "bushy plans" in which relations of k initial rels are
      * joined to relations of level-k initial rels, for 2 <= k <= level-2.
      *
      * We only consider bushy-plan joins for pairs of rels where there is a
      * suitable join clause (or join order restriction), in order to avoid
      * unreasonable growth of planning time.
      */
     for (k = 2;; k++)
     {
         int         other_level = level - k;
  
         /*
          * Since make_join_rel(x, y) handles both x,y and y,x cases, we only
          * need to go as far as the halfway point.
          */
         if (k > other_level)
             break;
  
         foreach(r, joinrels[k])
         {
             RelOptInfo *old_rel = (RelOptInfo *) lfirst(r);
             int         first_rel;
             ListCell   *r2;
  
             /*
              * We can ignore relations without join clauses here, unless they
              * participate in join-order restrictions --- then we might have
              * to force a bushy join plan.
              */
             if (old_rel->joininfo == NIL && !old_rel->has_eclass_joins &&
                 !has_join_restriction(root, old_rel))
                 continue;
  
             if (k == other_level)   /* only consider remaining rels */
                 first_rel = foreach_current_index(r) + 1;
             else
                 first_rel = 0;
  
             for_each_from(r2, joinrels[other_level], first_rel)
             {
                 RelOptInfo *new_rel = (RelOptInfo *) lfirst(r2);
  
                 if (!bms_overlap(old_rel->relids, new_rel->relids))
                 {
                     /*
                      * OK, we can build a rel of the right level from this
                      * pair of rels.  Do so if there is at least one relevant
                      * join clause or join order restriction.
                      */
                     if (have_relevant_joinclause(root, old_rel, new_rel) ||
                         have_join_order_restriction(root, old_rel, new_rel))
                     {
                         (void) make_join_rel(root, old_rel, new_rel);
                     }
                 }
             }
         }
     }
  
     /*----------
      * Last-ditch effort: if we failed to find any usable joins so far, force
      * a set of cartesian-product joins to be generated.  This handles the
      * special case where all the available rels have join clauses but we
      * cannot use any of those clauses yet.  This can only happen when we are
      * considering a join sub-problem (a sub-joinlist) and all the rels in the
      * sub-problem have only join clauses with rels outside the sub-problem.
      * An example is
      *
      *      SELECT ... FROM a INNER JOIN b ON TRUE, c, d, ...
      *      WHERE a.w = c.x and b.y = d.z;
      *
      * If the "a INNER JOIN b" sub-problem does not get flattened into the
      * upper level, we must be willing to make a cartesian join of a and b;
      * but the code above will not have done so, because it thought that both
      * a and b have joinclauses.  We consider only left-sided and right-sided
      * cartesian joins in this case (no bushy).
      *----------
      */
     if (joinrels[level] == NIL)
     {
         /*
          * This loop is just like the first one, except we always call
          * make_rels_by_clauseless_joins().
          */
         foreach(r, joinrels[level - 1])
         {
             RelOptInfo *old_rel = (RelOptInfo *) lfirst(r);
  
             make_rels_by_clauseless_joins(root,
                                           old_rel,
                                           joinrels[1]);
         }
  
         /*----------
          * When special joins are involved, there may be no legal way
          * to make an N-way join for some values of N.  For example consider
          *
          * SELECT ... FROM t1 WHERE
          *   x IN (SELECT ... FROM t2,t3 WHERE ...) AND
          *   y IN (SELECT ... FROM t4,t5 WHERE ...)
          *
          * We will flatten this query to a 5-way join problem, but there are
          * no 4-way joins that join_is_legal() will consider legal.  We have
          * to accept failure at level 4 and go on to discover a workable
          * bushy plan at level 5.
          *
          * However, if there are no special joins and no lateral references
          * then join_is_legal() should never fail, and so the following sanity
          * check is useful.
          *----------
          */
         if (joinrels[level] == NIL &&
             root->join_info_list == NIL &&
             !root->hasLateralRTEs)
             elog(ERROR, "failed to build any %d-way joins", level);
     }
 }

References Assert(), bms_overlap(), elog(), ERROR, for_each_from, foreach_current_index, RelOptInfo::has_eclass_joins, has_join_restriction(), PlannerInfo::hasLateralRTEs, have_join_order_restriction(), have_relevant_joinclause(), PlannerInfo::join_cur_level, PlannerInfo::join_info_list, RelOptInfo::joininfo, lfirst, make_join_rel(), make_rels_by_clause_joins(), make_rels_by_clauseless_joins(), NIL, and RelOptInfo::relids.

Referenced by standard_join_search().

◆ make_join_rel()

RelOptInfo* make_join_rel	(	PlannerInfo *	root,
		RelOptInfo *	rel1,
		RelOptInfo *	rel2
	)

Definition at line 670 of file joinrels.c.

 {
     Relids      joinrelids;
     SpecialJoinInfo *sjinfo;
     bool        reversed;
     List       *pushed_down_joins = NIL;
     SpecialJoinInfo sjinfo_data;
     RelOptInfo *joinrel;
     List       *restrictlist;
  
     /* We should never try to join two overlapping sets of rels. */
     Assert(!bms_overlap(rel1->relids, rel2->relids));
  
     /* Construct Relids set that identifies the joinrel (without OJ as yet). */
     joinrelids = bms_union(rel1->relids, rel2->relids);
  
     /* Check validity and determine join type. */
     if (!join_is_legal(root, rel1, rel2, joinrelids,
                        &sjinfo, &reversed))
     {
         /* invalid join path */
         bms_free(joinrelids);
         return NULL;
     }
  
     /*
      * Add outer join relid(s) to form the canonical relids.  Any added outer
      * joins besides sjinfo itself are appended to pushed_down_joins.
      */
     joinrelids = add_outer_joins_to_relids(root, joinrelids, sjinfo,
                                            &pushed_down_joins);
  
     /* Swap rels if needed to match the join info. */
     if (reversed)
     {
         RelOptInfo *trel = rel1;
  
         rel1 = rel2;
         rel2 = trel;
     }
  
     /*
      * If it's a plain inner join, then we won't have found anything in
      * join_info_list.  Make up a SpecialJoinInfo so that selectivity
      * estimation functions will know what's being joined.
      */
     if (sjinfo == NULL)
     {
         sjinfo = &sjinfo_data;
         sjinfo->type = T_SpecialJoinInfo;
         sjinfo->min_lefthand = rel1->relids;
         sjinfo->min_righthand = rel2->relids;
         sjinfo->syn_lefthand = rel1->relids;
         sjinfo->syn_righthand = rel2->relids;
         sjinfo->jointype = JOIN_INNER;
         sjinfo->ojrelid = 0;
         sjinfo->commute_above_l = NULL;
         sjinfo->commute_above_r = NULL;
         sjinfo->commute_below_l = NULL;
         sjinfo->commute_below_r = NULL;
         /* we don't bother trying to make the remaining fields valid */
         sjinfo->lhs_strict = false;
         sjinfo->semi_can_btree = false;
         sjinfo->semi_can_hash = false;
         sjinfo->semi_operators = NIL;
         sjinfo->semi_rhs_exprs = NIL;
     }
  
     /*
      * Find or build the join RelOptInfo, and compute the restrictlist that
      * goes with this particular joining.
      */
     joinrel = build_join_rel(root, joinrelids, rel1, rel2,
                              sjinfo, pushed_down_joins,
                              &restrictlist);
  
     /*
      * If we've already proven this join is empty, we needn't consider any
      * more paths for it.
      */
     if (is_dummy_rel(joinrel))
     {
         bms_free(joinrelids);
         return joinrel;
     }
  
     /* Add paths to the join relation. */
     populate_joinrel_with_paths(root, rel1, rel2, joinrel, sjinfo,
                                 restrictlist);
  
     bms_free(joinrelids);
  
     return joinrel;
 }

References add_outer_joins_to_relids(), Assert(), bms_free(), bms_overlap(), bms_union(), build_join_rel(), SpecialJoinInfo::commute_above_l, SpecialJoinInfo::commute_above_r, SpecialJoinInfo::commute_below_l, SpecialJoinInfo::commute_below_r, is_dummy_rel(), JOIN_INNER, join_is_legal(), SpecialJoinInfo::jointype, SpecialJoinInfo::lhs_strict, SpecialJoinInfo::min_lefthand, SpecialJoinInfo::min_righthand, NIL, SpecialJoinInfo::ojrelid, populate_joinrel_with_paths(), RelOptInfo::relids, SpecialJoinInfo::semi_can_btree, SpecialJoinInfo::semi_can_hash, SpecialJoinInfo::semi_operators, SpecialJoinInfo::semi_rhs_exprs, SpecialJoinInfo::syn_lefthand, and SpecialJoinInfo::syn_righthand.

Referenced by join_search_one_level(), make_rels_by_clause_joins(), make_rels_by_clauseless_joins(), and merge_clump().

◆ make_rels_by_clause_joins()

static void make_rels_by_clause_joins	(	PlannerInfo *	root,
		RelOptInfo *	old_rel,
		List *	other_rels,
		int	first_rel_idx
	)

static

Definition at line 278 of file joinrels.c.

 {
     ListCell   *l;
  
     for_each_from(l, other_rels, first_rel_idx)
     {
         RelOptInfo *other_rel = (RelOptInfo *) lfirst(l);
  
         if (!bms_overlap(old_rel->relids, other_rel->relids) &&
             (have_relevant_joinclause(root, old_rel, other_rel) ||
              have_join_order_restriction(root, old_rel, other_rel)))
         {
             (void) make_join_rel(root, old_rel, other_rel);
         }
     }
 }

References bms_overlap(), for_each_from, have_join_order_restriction(), have_relevant_joinclause(), lfirst, make_join_rel(), and RelOptInfo::relids.

Referenced by join_search_one_level().

◆ make_rels_by_clauseless_joins()

static void make_rels_by_clauseless_joins	(	PlannerInfo *	root,
		RelOptInfo *	old_rel,
		List *	other_rels
	)

static

Definition at line 312 of file joinrels.c.

 {
     ListCell   *l;
  
     foreach(l, other_rels)
     {
         RelOptInfo *other_rel = (RelOptInfo *) lfirst(l);
  
         if (!bms_overlap(other_rel->relids, old_rel->relids))
         {
             (void) make_join_rel(root, old_rel, other_rel);
         }
     }
 }

References bms_overlap(), lfirst, make_join_rel(), and RelOptInfo::relids.

Referenced by join_search_one_level().

◆ mark_dummy_rel()

void mark_dummy_rel ( RelOptInfo * rel )

Definition at line 1363 of file joinrels.c.

 {
     MemoryContext oldcontext;
  
     /* Already marked? */
     if (is_dummy_rel(rel))
         return;
  
     /* No, so choose correct context to make the dummy path in */
     oldcontext = MemoryContextSwitchTo(GetMemoryChunkContext(rel));
  
     /* Set dummy size estimate */
     rel->rows = 0;
  
     /* Evict any previously chosen paths */
     rel->pathlist = NIL;
     rel->partial_pathlist = NIL;
  
     /* Set up the dummy path */
     add_path(rel, (Path *) create_append_path(NULL, rel, NIL, NIL,
                                               NIL, rel->lateral_relids,
                                               0, false, -1));
  
     /* Set or update cheapest_total_path and related fields */
     set_cheapest(rel);
  
     MemoryContextSwitchTo(oldcontext);
 }

References add_path(), create_append_path(), GetMemoryChunkContext(), is_dummy_rel(), RelOptInfo::lateral_relids, MemoryContextSwitchTo(), NIL, RelOptInfo::partial_pathlist, RelOptInfo::pathlist, RelOptInfo::rows, and set_cheapest().

Referenced by build_simple_rel(), generate_partitionwise_join_paths(), and populate_joinrel_with_paths().

◆ populate_joinrel_with_paths()

static void populate_joinrel_with_paths	(	PlannerInfo *	root,
		RelOptInfo *	rel1,
		RelOptInfo *	rel2,
		RelOptInfo *	joinrel,
		SpecialJoinInfo *	sjinfo,
		List *	restrictlist
	)

static

Definition at line 875 of file joinrels.c.

 {
     /*
      * Consider paths using each rel as both outer and inner.  Depending on
      * the join type, a provably empty outer or inner rel might mean the join
      * is provably empty too; in which case throw away any previously computed
      * paths and mark the join as dummy.  (We do it this way since it's
      * conceivable that dummy-ness of a multi-element join might only be
      * noticeable for certain construction paths.)
      *
      * Also, a provably constant-false join restriction typically means that
      * we can skip evaluating one or both sides of the join.  We do this by
      * marking the appropriate rel as dummy.  For outer joins, a
      * constant-false restriction that is pushed down still means the whole
      * join is dummy, while a non-pushed-down one means that no inner rows
      * will join so we can treat the inner rel as dummy.
      *
      * We need only consider the jointypes that appear in join_info_list, plus
      * JOIN_INNER.
      */
     switch (sjinfo->jointype)
     {
         case JOIN_INNER:
             if (is_dummy_rel(rel1) || is_dummy_rel(rel2) ||
                 restriction_is_constant_false(restrictlist, joinrel, false))
             {
                 mark_dummy_rel(joinrel);
                 break;
             }
             add_paths_to_joinrel(root, joinrel, rel1, rel2,
                                  JOIN_INNER, sjinfo,
                                  restrictlist);
             add_paths_to_joinrel(root, joinrel, rel2, rel1,
                                  JOIN_INNER, sjinfo,
                                  restrictlist);
             break;
         case JOIN_LEFT:
             if (is_dummy_rel(rel1) ||
                 restriction_is_constant_false(restrictlist, joinrel, true))
             {
                 mark_dummy_rel(joinrel);
                 break;
             }
             if (restriction_is_constant_false(restrictlist, joinrel, false) &&
                 bms_is_subset(rel2->relids, sjinfo->syn_righthand))
                 mark_dummy_rel(rel2);
             add_paths_to_joinrel(root, joinrel, rel1, rel2,
                                  JOIN_LEFT, sjinfo,
                                  restrictlist);
             add_paths_to_joinrel(root, joinrel, rel2, rel1,
                                  JOIN_RIGHT, sjinfo,
                                  restrictlist);
             break;
         case JOIN_FULL:
             if ((is_dummy_rel(rel1) && is_dummy_rel(rel2)) ||
                 restriction_is_constant_false(restrictlist, joinrel, true))
             {
                 mark_dummy_rel(joinrel);
                 break;
             }
             add_paths_to_joinrel(root, joinrel, rel1, rel2,
                                  JOIN_FULL, sjinfo,
                                  restrictlist);
             add_paths_to_joinrel(root, joinrel, rel2, rel1,
                                  JOIN_FULL, sjinfo,
                                  restrictlist);
  
             /*
              * If there are join quals that aren't mergeable or hashable, we
              * may not be able to build any valid plan.  Complain here so that
              * we can give a somewhat-useful error message.  (Since we have no
              * flexibility of planning for a full join, there's no chance of
              * succeeding later with another pair of input rels.)
              */
             if (joinrel->pathlist == NIL)
                 ereport(ERROR,
                         (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                          errmsg("FULL JOIN is only supported with merge-joinable or hash-joinable join conditions")));
             break;
         case JOIN_SEMI:
  
             /*
              * We might have a normal semijoin, or a case where we don't have
              * enough rels to do the semijoin but can unique-ify the RHS and
              * then do an innerjoin (see comments in join_is_legal).  In the
              * latter case we can't apply JOIN_SEMI joining.
              */
             if (bms_is_subset(sjinfo->min_lefthand, rel1->relids) &&
                 bms_is_subset(sjinfo->min_righthand, rel2->relids))
             {
                 if (is_dummy_rel(rel1) || is_dummy_rel(rel2) ||
                     restriction_is_constant_false(restrictlist, joinrel, false))
                 {
                     mark_dummy_rel(joinrel);
                     break;
                 }
                 add_paths_to_joinrel(root, joinrel, rel1, rel2,
                                      JOIN_SEMI, sjinfo,
                                      restrictlist);
             }
  
             /*
              * If we know how to unique-ify the RHS and one input rel is
              * exactly the RHS (not a superset) we can consider unique-ifying
              * it and then doing a regular join.  (The create_unique_path
              * check here is probably redundant with what join_is_legal did,
              * but if so the check is cheap because it's cached.  So test
              * anyway to be sure.)
              */
             if (bms_equal(sjinfo->syn_righthand, rel2->relids) &&
                 create_unique_path(root, rel2, rel2->cheapest_total_path,
                                    sjinfo) != NULL)
             {
                 if (is_dummy_rel(rel1) || is_dummy_rel(rel2) ||
                     restriction_is_constant_false(restrictlist, joinrel, false))
                 {
                     mark_dummy_rel(joinrel);
                     break;
                 }
                 add_paths_to_joinrel(root, joinrel, rel1, rel2,
                                      JOIN_UNIQUE_INNER, sjinfo,
                                      restrictlist);
                 add_paths_to_joinrel(root, joinrel, rel2, rel1,
                                      JOIN_UNIQUE_OUTER, sjinfo,
                                      restrictlist);
             }
             break;
         case JOIN_ANTI:
             if (is_dummy_rel(rel1) ||
                 restriction_is_constant_false(restrictlist, joinrel, true))
             {
                 mark_dummy_rel(joinrel);
                 break;
             }
             if (restriction_is_constant_false(restrictlist, joinrel, false) &&
                 bms_is_subset(rel2->relids, sjinfo->syn_righthand))
                 mark_dummy_rel(rel2);
             add_paths_to_joinrel(root, joinrel, rel1, rel2,
                                  JOIN_ANTI, sjinfo,
                                  restrictlist);
             add_paths_to_joinrel(root, joinrel, rel2, rel1,
                                  JOIN_RIGHT_ANTI, sjinfo,
                                  restrictlist);
             break;
         default:
             /* other values not expected here */
             elog(ERROR, "unrecognized join type: %d", (int) sjinfo->jointype);
             break;
     }
  
     /* Apply partitionwise join technique, if possible. */
     try_partitionwise_join(root, rel1, rel2, joinrel, sjinfo, restrictlist);
 }

References add_paths_to_joinrel(), bms_equal(), bms_is_subset(), RelOptInfo::cheapest_total_path, create_unique_path(), elog(), ereport, errcode(), errmsg(), ERROR, is_dummy_rel(), JOIN_ANTI, JOIN_FULL, JOIN_INNER, JOIN_LEFT, JOIN_RIGHT, JOIN_RIGHT_ANTI, JOIN_SEMI, JOIN_UNIQUE_INNER, JOIN_UNIQUE_OUTER, SpecialJoinInfo::jointype, mark_dummy_rel(), SpecialJoinInfo::min_lefthand, SpecialJoinInfo::min_righthand, NIL, RelOptInfo::pathlist, RelOptInfo::relids, restriction_is_constant_false(), SpecialJoinInfo::syn_righthand, and try_partitionwise_join().

Referenced by make_join_rel(), and try_partitionwise_join().

◆ restriction_is_constant_false()

static bool restriction_is_constant_false	(	List *	restrictlist,
		RelOptInfo *	joinrel,
		bool	only_pushed_down
	)

static

Definition at line 1406 of file joinrels.c.

 {
     ListCell   *lc;
  
     /*
      * Despite the above comment, the restriction list we see here might
      * possibly have other members besides the FALSE constant, since other
      * quals could get "pushed down" to the outer join level.  So we check
      * each member of the list.
      */
     foreach(lc, restrictlist)
     {
         RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
  
         if (only_pushed_down && !RINFO_IS_PUSHED_DOWN(rinfo, joinrel->relids))
             continue;
  
         if (rinfo->clause && IsA(rinfo->clause, Const))
         {
             Const      *con = (Const *) rinfo->clause;
  
             /* constant NULL is as good as constant FALSE for our purposes */
             if (con->constisnull)
                 return true;
             if (!DatumGetBool(con->constvalue))
                 return true;
         }
     }
     return false;
 }

References RestrictInfo::clause, DatumGetBool(), if(), IsA, lfirst_node, RelOptInfo::relids, and RINFO_IS_PUSHED_DOWN.

Referenced by populate_joinrel_with_paths().

◆ try_partitionwise_join()

static void try_partitionwise_join	(	PlannerInfo *	root,
		RelOptInfo *	rel1,
		RelOptInfo *	rel2,
		RelOptInfo *	joinrel,
		SpecialJoinInfo *	parent_sjinfo,
		List *	parent_restrictlist
	)

static

Definition at line 1460 of file joinrels.c.

 {
     bool        rel1_is_simple = IS_SIMPLE_REL(rel1);
     bool        rel2_is_simple = IS_SIMPLE_REL(rel2);
     List       *parts1 = NIL;
     List       *parts2 = NIL;
     ListCell   *lcr1 = NULL;
     ListCell   *lcr2 = NULL;
     int         cnt_parts;
  
     /* Guard against stack overflow due to overly deep partition hierarchy. */
     check_stack_depth();
  
     /* Nothing to do, if the join relation is not partitioned. */
     if (joinrel->part_scheme == NULL || joinrel->nparts == 0)
         return;
  
     /* The join relation should have consider_partitionwise_join set. */
     Assert(joinrel->consider_partitionwise_join);
  
     /*
      * We can not perform partitionwise join if either of the joining
      * relations is not partitioned.
      */
     if (!IS_PARTITIONED_REL(rel1) || !IS_PARTITIONED_REL(rel2))
         return;
  
     Assert(REL_HAS_ALL_PART_PROPS(rel1) && REL_HAS_ALL_PART_PROPS(rel2));
  
     /* The joining relations should have consider_partitionwise_join set. */
     Assert(rel1->consider_partitionwise_join &&
            rel2->consider_partitionwise_join);
  
     /*
      * The partition scheme of the join relation should match that of the
      * joining relations.
      */
     Assert(joinrel->part_scheme == rel1->part_scheme &&
            joinrel->part_scheme == rel2->part_scheme);
  
     Assert(!(joinrel->partbounds_merged && (joinrel->nparts <= 0)));
  
     compute_partition_bounds(root, rel1, rel2, joinrel, parent_sjinfo,
                              &parts1, &parts2);
  
     if (joinrel->partbounds_merged)
     {
         lcr1 = list_head(parts1);
         lcr2 = list_head(parts2);
     }
  
     /*
      * Create child-join relations for this partitioned join, if those don't
      * exist. Add paths to child-joins for a pair of child relations
      * corresponding to the given pair of parent relations.
      */
     for (cnt_parts = 0; cnt_parts < joinrel->nparts; cnt_parts++)
     {
         RelOptInfo *child_rel1;
         RelOptInfo *child_rel2;
         bool        rel1_empty;
         bool        rel2_empty;
         SpecialJoinInfo *child_sjinfo;
         List       *child_restrictlist;
         RelOptInfo *child_joinrel;
         AppendRelInfo **appinfos;
         int         nappinfos;
  
         if (joinrel->partbounds_merged)
         {
             child_rel1 = lfirst_node(RelOptInfo, lcr1);
             child_rel2 = lfirst_node(RelOptInfo, lcr2);
             lcr1 = lnext(parts1, lcr1);
             lcr2 = lnext(parts2, lcr2);
         }
         else
         {
             child_rel1 = rel1->part_rels[cnt_parts];
             child_rel2 = rel2->part_rels[cnt_parts];
         }
  
         rel1_empty = (child_rel1 == NULL || IS_DUMMY_REL(child_rel1));
         rel2_empty = (child_rel2 == NULL || IS_DUMMY_REL(child_rel2));
  
         /*
          * Check for cases where we can prove that this segment of the join
          * returns no rows, due to one or both inputs being empty (including
          * inputs that have been pruned away entirely).  If so just ignore it.
          * These rules are equivalent to populate_joinrel_with_paths's rules
          * for dummy input relations.
          */
         switch (parent_sjinfo->jointype)
         {
             case JOIN_INNER:
             case JOIN_SEMI:
                 if (rel1_empty || rel2_empty)
                     continue;   /* ignore this join segment */
                 break;
             case JOIN_LEFT:
             case JOIN_ANTI:
                 if (rel1_empty)
                     continue;   /* ignore this join segment */
                 break;
             case JOIN_FULL:
                 if (rel1_empty && rel2_empty)
                     continue;   /* ignore this join segment */
                 break;
             default:
                 /* other values not expected here */
                 elog(ERROR, "unrecognized join type: %d",
                      (int) parent_sjinfo->jointype);
                 break;
         }
  
         /*
          * If a child has been pruned entirely then we can't generate paths
          * for it, so we have to reject partitionwise joining unless we were
          * able to eliminate this partition above.
          */
         if (child_rel1 == NULL || child_rel2 == NULL)
         {
             /*
              * Mark the joinrel as unpartitioned so that later functions treat
              * it correctly.
              */
             joinrel->nparts = 0;
             return;
         }
  
         /*
          * If a leaf relation has consider_partitionwise_join=false, it means
          * that it's a dummy relation for which we skipped setting up tlist
          * expressions and adding EC members in set_append_rel_size(), so
          * again we have to fail here.
          */
         if (rel1_is_simple && !child_rel1->consider_partitionwise_join)
         {
             Assert(child_rel1->reloptkind == RELOPT_OTHER_MEMBER_REL);
             Assert(IS_DUMMY_REL(child_rel1));
             joinrel->nparts = 0;
             return;
         }
         if (rel2_is_simple && !child_rel2->consider_partitionwise_join)
         {
             Assert(child_rel2->reloptkind == RELOPT_OTHER_MEMBER_REL);
             Assert(IS_DUMMY_REL(child_rel2));
             joinrel->nparts = 0;
             return;
         }
  
         /* We should never try to join two overlapping sets of rels. */
         Assert(!bms_overlap(child_rel1->relids, child_rel2->relids));
  
         /*
          * Construct SpecialJoinInfo from parent join relations's
          * SpecialJoinInfo.
          */
         child_sjinfo = build_child_join_sjinfo(root, parent_sjinfo,
                                                child_rel1->relids,
                                                child_rel2->relids);
  
         /* Find the AppendRelInfo structures */
         appinfos = find_appinfos_by_relids(root,
                                            bms_union(child_rel1->relids,
                                                      child_rel2->relids),
                                            &nappinfos);
  
         /*
          * Construct restrictions applicable to the child join from those
          * applicable to the parent join.
          */
         child_restrictlist =
             (List *) adjust_appendrel_attrs(root,
                                             (Node *) parent_restrictlist,
                                             nappinfos, appinfos);
  
         /* Find or construct the child join's RelOptInfo */
         child_joinrel = joinrel->part_rels[cnt_parts];
         if (!child_joinrel)
         {
             child_joinrel = build_child_join_rel(root, child_rel1, child_rel2,
                                                  joinrel, child_restrictlist,
                                                  child_sjinfo);
             joinrel->part_rels[cnt_parts] = child_joinrel;
             joinrel->live_parts = bms_add_member(joinrel->live_parts, cnt_parts);
             joinrel->all_partrels = bms_add_members(joinrel->all_partrels,
                                                     child_joinrel->relids);
         }
  
         /* Assert we got the right one */
         Assert(bms_equal(child_joinrel->relids,
                          adjust_child_relids(joinrel->relids,
                                              nappinfos, appinfos)));
  
         /* And make paths for the child join */
         populate_joinrel_with_paths(root, child_rel1, child_rel2,
                                     child_joinrel, child_sjinfo,
                                     child_restrictlist);
  
         pfree(appinfos);
     }
 }

References adjust_appendrel_attrs(), adjust_child_relids(), RelOptInfo::all_partrels, Assert(), bms_add_member(), bms_add_members(), bms_equal(), bms_overlap(), bms_union(), build_child_join_rel(), build_child_join_sjinfo(), check_stack_depth(), compute_partition_bounds(), RelOptInfo::consider_partitionwise_join, elog(), ERROR, find_appinfos_by_relids(), IS_DUMMY_REL, IS_PARTITIONED_REL, IS_SIMPLE_REL, JOIN_ANTI, JOIN_FULL, JOIN_INNER, JOIN_LEFT, JOIN_SEMI, SpecialJoinInfo::jointype, lfirst_node, list_head(), RelOptInfo::live_parts, lnext(), NIL, RelOptInfo::nparts, RelOptInfo::partbounds_merged, pfree(), populate_joinrel_with_paths(), REL_HAS_ALL_PART_PROPS, RelOptInfo::relids, RELOPT_OTHER_MEMBER_REL, and RelOptInfo::reloptkind.

Referenced by populate_joinrel_with_paths().

Functions

Function Documentation

◆ add_outer_joins_to_relids()

◆ build_child_join_sjinfo()

◆ compute_partition_bounds()

◆ get_matching_part_pairs()

◆ has_join_restriction()

◆ has_legal_joinclause()

◆ have_dangerous_phv()

◆ have_join_order_restriction()

◆ is_dummy_rel()

◆ join_is_legal()

◆ join_search_one_level()

◆ make_join_rel()

◆ make_rels_by_clause_joins()

◆ make_rels_by_clauseless_joins()

◆ mark_dummy_rel()

◆ populate_joinrel_with_paths()

◆ restriction_is_constant_false()

◆ try_partitionwise_join()