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Commit5278d0a

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Reduce memory used by partitionwise joins
Specifically, this commit reduces the memory consumed by theSpecialJoinInfos that are allocated for child joins intry_partitionwise_join() by freeing them at the end of creating pathsfor each child join.A SpecialJoinInfo allocated for a given child join is a copy of theparent join's SpecialJoinInfo, which contains the translated copiesof the various Relids bitmapsets and semi_rhs_exprs, which is a Listof Nodes. The newly added freeing step frees the struct itself andthe various bitmapsets, but not semi_rhs_exprs, because there's nohandy function to free the memory of Node trees.Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>Reviewed-by: Richard Guo <guofenglinux@gmail.com>Reviewed-by: Amit Langote <amitlangote09@gmail.com>Reviewed-by: Andrey Lepikhov <a.lepikhov@postgrespro.ru>Reviewed-by: Tomas Vondra <tomas.vondra@enterprisedb.com>Discussion:https://postgr.es/m/CAExHW5tHqEf3ASVqvFFcghYGPfpy7o3xnvhHwBGbJFMRH8KjNw@mail.gmail.com
1 parent619bc23 commit5278d0a

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3 files changed

+42
-2
lines changed

3 files changed

+42
-2
lines changed

‎src/backend/optimizer/path/joinrels.c‎

Lines changed: 36 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -45,6 +45,7 @@ static void try_partitionwise_join(PlannerInfo *root, RelOptInfo *rel1,
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staticSpecialJoinInfo*build_child_join_sjinfo(PlannerInfo*root,
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SpecialJoinInfo*parent_sjinfo,
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Relidsleft_relids,Relidsright_relids);
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staticvoidfree_child_join_sjinfo(SpecialJoinInfo*child_sjinfo);
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staticvoidcompute_partition_bounds(PlannerInfo*root,RelOptInfo*rel1,
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RelOptInfo*rel2,RelOptInfo*joinrel,
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SpecialJoinInfo*parent_sjinfo,
@@ -1659,13 +1660,17 @@ try_partitionwise_join(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
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child_restrictlist);
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16611662
pfree(appinfos);
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free_child_join_sjinfo(child_sjinfo);
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}
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}
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/*
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* Construct the SpecialJoinInfo for a child-join by translating
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* SpecialJoinInfo for the join between parents. left_relids and right_relids
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* are the relids of left and right side of the join respectively.
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*
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* If translations are added to or removed from this function, consider
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* updating free_child_join_sjinfo() accordingly.
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*/
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staticSpecialJoinInfo*
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build_child_join_sjinfo(PlannerInfo*root,SpecialJoinInfo*parent_sjinfo,
@@ -1705,6 +1710,37 @@ build_child_join_sjinfo(PlannerInfo *root, SpecialJoinInfo *parent_sjinfo,
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returnsjinfo;
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}
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/*
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* free_child_join_sjinfo
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*Free memory consumed by a SpecialJoinInfo created by
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*build_child_join_sjinfo()
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*
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* Only members that are translated copies of their counterpart in the parent
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* SpecialJoinInfo are freed here.
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*/
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staticvoid
1722+
free_child_join_sjinfo(SpecialJoinInfo*sjinfo)
1723+
{
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/*
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* Dummy SpecialJoinInfos of inner joins do not have any translated fields
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* and hence no fields that to be freed.
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*/
1728+
if (sjinfo->jointype!=JOIN_INNER)
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{
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bms_free(sjinfo->min_lefthand);
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bms_free(sjinfo->min_righthand);
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bms_free(sjinfo->syn_lefthand);
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bms_free(sjinfo->syn_righthand);
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/*
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* semi_rhs_exprs may in principle be freed, but a simple pfree() does
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* not suffice, so we leave it alone.
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*/
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}
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pfree(sjinfo);
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}
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/*
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* compute_partition_bounds
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*Compute the partition bounds for a join rel from those for inputs

‎src/backend/optimizer/util/pathnode.c‎

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1707,8 +1707,9 @@ create_unique_path(PlannerInfo *root, RelOptInfo *rel, Path *subpath,
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pathnode->subpath=subpath;
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/*
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* Under GEQO, the sjinfo might be short-lived, so we'd better make copies
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* of data structures we extract from it.
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* Under GEQO and when planning child joins, the sjinfo might be
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* short-lived, so we'd better make copies of data structures we extract
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* from it.
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*/
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pathnode->in_operators=copyObject(sjinfo->semi_operators);
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pathnode->uniq_exprs=copyObject(sjinfo->semi_rhs_exprs);

‎src/include/nodes/pathnodes.h‎

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2856,6 +2856,9 @@ typedef struct PlaceHolderVar
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* cost estimation purposes it is sometimes useful to know the join size under
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* plain innerjoin semantics. Note that lhs_strict and the semi_xxx fields
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* are not set meaningfully within such structs.
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*
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* We also create transient SpecialJoinInfos for child joins during
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* partiotionwise join planning, which are also not present in join_info_list.
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*/
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#ifndefHAVE_SPECIALJOININFO_TYPEDEF
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typedefstructSpecialJoinInfoSpecialJoinInfo;

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