Skip to content

Commit aa97890

Browse files
committed
Don't search for volatile expr in find_em_expr_usable_for_sorting_rel
While prepare_sort_from_pathkeys has to be concerned about matching up a volatile expression to the proper tlist entry, we don't need to do that in find_em_expr_usable_for_sorting_rel becausee such a sort will have to be postponed anyway. Author: James Coleman Reviewed-by: Tomas Vondra Backpatch-through: 13 Discussion: https://postgr.es/m/CAAaqYe8cK3g5CfLC4w7bs%3DhC0mSksZC%3DH5M8LSchj5e5OxpTAg%40mail.gmail.com
1 parent d016763 commit aa97890

File tree

1 file changed

+5
-23
lines changed

1 file changed

+5
-23
lines changed

src/backend/optimizer/path/equivclass.c

Lines changed: 5 additions & 23 deletions
Original file line numberDiff line numberDiff line change
@@ -813,8 +813,6 @@ find_em_expr_usable_for_sorting_rel(PlannerInfo *root, EquivalenceClass *ec,
813813
{
814814
EquivalenceMember *em = lfirst(lc_em);
815815
Expr *em_expr = em->em_expr;
816-
PathTarget *target = rel->reltarget;
817-
ListCell *lc_target_expr;
818816

819817
/*
820818
* We shouldn't be trying to sort by an equivalence class that
@@ -848,30 +846,14 @@ find_em_expr_usable_for_sorting_rel(PlannerInfo *root, EquivalenceClass *ec,
848846
* As long as the expression isn't volatile then
849847
* prepare_sort_from_pathkeys is able to generate a new target entry,
850848
* so there's no need to verify that one already exists.
849+
*
850+
* While prepare_sort_from_pathkeys has to be concerned about matching
851+
* up a volatile expression to the proper tlist entry, it doesn't seem
852+
* valuable here to expend the work trying to find a match in the
853+
* target's exprs since such a sort will have to be postponed anyway.
851854
*/
852855
if (!ec->ec_has_volatile)
853856
return em->em_expr;
854-
855-
/*
856-
* If, however, it's volatile, we have to verify that the
857-
* equivalence member's expr is already generated in the
858-
* relation's target (we do strip relabels first from both
859-
* expressions, which is cheap and might allow us to match
860-
* more expressions).
861-
*/
862-
while (em_expr && IsA(em_expr, RelabelType))
863-
em_expr = ((RelabelType *) em_expr)->arg;
864-
865-
foreach(lc_target_expr, target->exprs)
866-
{
867-
Expr *target_expr = lfirst(lc_target_expr);
868-
869-
while (target_expr && IsA(target_expr, RelabelType))
870-
target_expr = ((RelabelType *) target_expr)->arg;
871-
872-
if (equal(target_expr, em_expr))
873-
return em->em_expr;
874-
}
875857
}
876858

877859
/* We didn't find any suitable equivalence class expression */

0 commit comments

Comments
 (0)