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Track the number of presorted outer pathkeys in MergePath

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When creating an explicit Sort node for the outer path of a mergejoin,
we need to determine the number of presorted keys of the outer path to
decide whether explicit incremental sort can be applied.  Currently,
this is done by repeatedly calling pathkeys_count_contained_in.

This patch caches the number of presorted outer pathkeys in MergePath,
allowing us to save several calls to pathkeys_count_contained_in.  It
can be considered a complement to the changes in commit 828e94c9d.

Reported-by: David Rowley <dgrowleyml@gmail.com>
Author: Richard Guo <guofenglinux@gmail.com>
Reviewed-by: Tender Wang <tndrwang@gmail.com>
Discussion: https://postgr.es/m/CAApHDvqvBireB_w6x8BN5txdvBEHxVgZBt=rUnpf5ww5P_E_ww@mail.gmail.com
This commit is contained in:
Richard Guo
2025-05-08 18:21:32 +09:00
parent 773db22269
commit c06e909c26
8 changed files with 104 additions and 66 deletions
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5
src/backend/optimizer/util/pathnode.c
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@@ -2626,6 +2626,7 @@ create_nestloop_path(PlannerInfo *root,
* (this should be a subset of the restrict_clauses list)
* 'outersortkeys' are the sort varkeys for the outer relation
* 'innersortkeys' are the sort varkeys for the inner relation
* 'outer_presorted_keys' is the number of presorted keys of the outer path
*/
MergePath *
create_mergejoin_path(PlannerInfo *root,
@@ -2640,7 +2641,8 @@ create_mergejoin_path(PlannerInfo *root,
Relids required_outer,
List *mergeclauses,
List *outersortkeys,
List *innersortkeys)
List *innersortkeys,
int outer_presorted_keys)
{
MergePath *pathnode = makeNode(MergePath);
@@ -2669,6 +2671,7 @@ create_mergejoin_path(PlannerInfo *root,
pathnode->path_mergeclauses = mergeclauses;
pathnode->outersortkeys = outersortkeys;
pathnode->innersortkeys = innersortkeys;
pathnode->outer_presorted_keys = outer_presorted_keys;
/* pathnode->skip_mark_restore will be set by final_cost_mergejoin */
/* pathnode->materialize_inner will be set by final_cost_mergejoin */