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Revert "Use CP_SMALL_TLIST for hash aggregate" 

This reverts commit 4cad2534da due to a
performance regression. It will be replaced by a new approach in an
upcoming commit.

Reported-by: Andres Freund
Discussion: https://postgr.es/m/20200614181418.mx4bvljmfkkhoqzl@alap3.anarazel.de
Backpatch-through: 13
This commit is contained in:
Jeff Davis 2020-07-12 16:46:19 -07:00
parent b074813d48
commit 926ecf83c0
2 changed files with 6 additions and 26 deletions
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4
contrib/postgres_fdw/expected/postgres_fdw.out
View File

@ -2715,7 +2715,7 @@ select sum(c1) from ft1 group by c2 having avg(c1 * (random() <= 1)::int) > 100
Group Key: ft1.c2
Filter: (avg((ft1.c1 * ((random() <= '1'::double precision))::integer)) > '100'::numeric)
-> Foreign Scan on public.ft1
Output: c2, c1
Output: c1, c2
Remote SQL: SELECT "C 1", c2 FROM "S 1"."T 1"
(10 rows)
@ -2964,7 +2964,7 @@ select sum(c1) filter (where (c1 / c1) * random() <= 1) from ft1 group by c2 ord
Output: sum(c1) FILTER (WHERE ((((c1 / c1))::double precision * random()) <= '1'::double precision)), c2
Group Key: ft1.c2
-> Foreign Scan on public.ft1
Output: c2, c1
Output: c1, c2
Remote SQL: SELECT "C 1", c2 FROM "S 1"."T 1"
(9 rows)

28
src/backend/optimizer/plan/createplan.c
View File

@ -2113,22 +2113,12 @@ create_agg_plan(PlannerInfo *root, AggPath *best_path)
Plan *subplan;
List *tlist;
List *quals;
int flags;
/*
* Agg can project, so no need to be terribly picky about child tlist, but
* we do need grouping columns to be available. We are a bit more careful
* with hash aggregate, where we explicitly request small tlist to
* minimize I/O needed for spilling (we can't be sure spilling won't be
* necessary, so we just do it every time).
* we do need grouping columns to be available
*/
flags = CP_LABEL_TLIST;
/* ensure small tlist for hash aggregate */
if (best_path->aggstrategy == AGG_HASHED)
flags |= CP_SMALL_TLIST;
subplan = create_plan_recurse(root, best_path->subpath, flags);
subplan = create_plan_recurse(root, best_path->subpath, CP_LABEL_TLIST);
tlist = build_path_tlist(root, &best_path->path);
@ -2210,7 +2200,6 @@ create_groupingsets_plan(PlannerInfo *root, GroupingSetsPath *best_path)
int maxref;
List *chain;
ListCell *lc;
int flags;
/* Shouldn't get here without grouping sets */
Assert(root->parse->groupingSets);
@ -2218,18 +2207,9 @@ create_groupingsets_plan(PlannerInfo *root, GroupingSetsPath *best_path)
/*
* Agg can project, so no need to be terribly picky about child tlist, but
* we do need grouping columns to be available. We are a bit more careful
* with hash aggregate, where we explicitly request small tlist to
* minimize I/O needed for spilling (we can't be sure spilling won't be
* necessary, so we just do it every time).
* we do need grouping columns to be available
*/
flags = CP_LABEL_TLIST;
/* ensure small tlist for hash aggregate */
if (best_path->aggstrategy == AGG_HASHED)
flags |= CP_SMALL_TLIST;
subplan = create_plan_recurse(root, best_path->subpath, flags);
subplan = create_plan_recurse(root, best_path->subpath, CP_LABEL_TLIST);
/*
* Compute the mapping from tleSortGroupRef to column index in the child's