From 4a37f580806a388e5d78e452426b99f738a583e5 Mon Sep 17 00:00:00 2001 From: Ashutosh Bapat Date: Wed, 26 Jul 2023 12:08:55 +0530 Subject: [PATCH] Avoid repeated computations in try_partitionwise_join() and minions try_partitionwise_join() computes bms_union() of Bitmapsets representing joining child relations and fetches AppendRelInfos corresponding child base relations participating in the join. The same computation is repeated in build_child_join_rel(). Avoid this repeated computation by performing it only once in try_partitionwise_join() and passing the AppendRelInfos gathered there to build_child_join_rel(). Bitmapsets representing child relids consume large memory when thousands of partitions are involved. By performing the bms_union() only once and freeing the result when it's no longer required, we save memory. The memory savings are considerable when many partitioned tables with thousands of partitions are joined using partitionwise join. Author: Ashutosh Bapat Discussion: https://www.postgresql.org/message-id/flat/CAExHW5snUW7pD2RdtaBa1T_TqJYaY6W_YPVjWDrgSf33i-0uqA%40mail.gmail.com#1f9e0950518310dd300e21574979646f --- src/backend/optimizer/path/joinrels.c | 10 ++++++---- src/backend/optimizer/util/relnode.c | 18 +++--------------- src/include/optimizer/pathnode.h | 3 ++- 3 files changed, 11 insertions(+), 20 deletions(-) diff --git a/src/backend/optimizer/path/joinrels.c b/src/backend/optimizer/path/joinrels.c index f3a9412d18..887135869c 100644 --- a/src/backend/optimizer/path/joinrels.c +++ b/src/backend/optimizer/path/joinrels.c @@ -1544,6 +1544,7 @@ try_partitionwise_join(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2, RelOptInfo *child_joinrel; AppendRelInfo **appinfos; int nappinfos; + Bitmapset *child_relids = NULL; if (joinrel->partbounds_merged) { @@ -1639,9 +1640,8 @@ try_partitionwise_join(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2, child_rel2->relids); /* Find the AppendRelInfo structures */ - appinfos = find_appinfos_by_relids(root, - bms_union(child_rel1->relids, - child_rel2->relids), + child_relids = bms_union(child_rel1->relids, child_rel2->relids); + appinfos = find_appinfos_by_relids(root, child_relids, &nappinfos); /* @@ -1659,7 +1659,8 @@ try_partitionwise_join(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2, { child_joinrel = build_child_join_rel(root, child_rel1, child_rel2, joinrel, child_restrictlist, - child_sjinfo); + child_sjinfo, appinfos, + nappinfos); 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, @@ -1678,6 +1679,7 @@ try_partitionwise_join(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2, pfree(appinfos); free_child_join_sjinfo(child_sjinfo); + bms_free(child_relids); } } diff --git a/src/backend/optimizer/util/relnode.c b/src/backend/optimizer/util/relnode.c index e05b21c884..989bee0fa8 100644 --- a/src/backend/optimizer/util/relnode.c +++ b/src/backend/optimizer/util/relnode.c @@ -876,15 +876,15 @@ build_join_rel(PlannerInfo *root, * 'restrictlist': list of RestrictInfo nodes that apply to this particular * pair of joinable relations * 'sjinfo': child join's join-type details + * 'appinfos' and 'nappinfos': AppendRelInfo array for child relids */ RelOptInfo * build_child_join_rel(PlannerInfo *root, RelOptInfo *outer_rel, RelOptInfo *inner_rel, RelOptInfo *parent_joinrel, - List *restrictlist, SpecialJoinInfo *sjinfo) + List *restrictlist, SpecialJoinInfo *sjinfo, + AppendRelInfo **appinfos, int nappinfos) { RelOptInfo *joinrel = makeNode(RelOptInfo); - AppendRelInfo **appinfos; - int nappinfos; /* Only joins between "other" relations land here. */ Assert(IS_OTHER_REL(outer_rel) && IS_OTHER_REL(inner_rel)); @@ -892,16 +892,6 @@ build_child_join_rel(PlannerInfo *root, RelOptInfo *outer_rel, /* The parent joinrel should have consider_partitionwise_join set. */ Assert(parent_joinrel->consider_partitionwise_join); - /* - * Find the AppendRelInfo structures for the child baserels. We'll need - * these for computing the child join's relid set, and later for mapping - * Vars to the child rel. - */ - appinfos = find_appinfos_by_relids(root, - bms_union(outer_rel->relids, - inner_rel->relids), - &nappinfos); - joinrel->reloptkind = RELOPT_OTHER_JOINREL; joinrel->relids = adjust_child_relids(parent_joinrel->relids, nappinfos, appinfos); @@ -1017,8 +1007,6 @@ build_child_join_rel(PlannerInfo *root, RelOptInfo *outer_rel, nappinfos, appinfos, parent_joinrel, joinrel); - pfree(appinfos); - return joinrel; } diff --git a/src/include/optimizer/pathnode.h b/src/include/optimizer/pathnode.h index 112e7c23d4..71fda9f2a4 100644 --- a/src/include/optimizer/pathnode.h +++ b/src/include/optimizer/pathnode.h @@ -346,6 +346,7 @@ extern Bitmapset *get_param_path_clause_serials(Path *path); extern RelOptInfo *build_child_join_rel(PlannerInfo *root, RelOptInfo *outer_rel, RelOptInfo *inner_rel, RelOptInfo *parent_joinrel, List *restrictlist, - SpecialJoinInfo *sjinfo); + SpecialJoinInfo *sjinfo, + AppendRelInfo **appinfos, int nappinfos); #endif /* PATHNODE_H */ -- 2.34.1