Skip to content

Commit 53c6daf

Browse files
committed
Fix two latent(?) bugs in equivclass.c.
get_eclass_for_sort_expr() computes expr_relids and nullable_relids early on, even though they won't be needed unless we make a new EquivalenceClass, which we often don't. Aside from the probably-minor inefficiency, there's a memory management problem: these bitmapsets will be built in the caller's context, leading to dangling pointers if that is shorter-lived than root->planner_cxt. This would be a live bug if get_eclass_for_sort_expr() could be called with create_it = true during GEQO join planning. So far as I can find, the core code never does that, but it's hard to be sure that no extensions do, especially since the comments make it clear that that's supposed to be a supported case. Fix by not computing these values until we've switched into planner_cxt to build the new EquivalenceClass. generate_join_implied_equalities() uses inner_rel->relids to look up relevant eclasses, but it ought to be using nominal_inner_relids. This is presently harmless because a child RelOptInfo will always have exactly the same eclass_indexes as its topmost parent; but that might not be true forever, and anyway it makes the code confusing. The first of these is old (introduced by me in f3b3b8d), so back-patch to all supported branches. The second only dates to v13, but we might as well back-patch it to keep the code looking similar across branches. Discussion: https://postgr.es/m/1508010.1601832581@sss.pgh.pa.us
1 parent 9cc3d61 commit 53c6daf

File tree

1 file changed

+8
-8
lines changed

1 file changed

+8
-8
lines changed

src/backend/optimizer/path/equivclass.c

Lines changed: 8 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -634,12 +634,6 @@ get_eclass_for_sort_expr(PlannerInfo *root,
634634
*/
635635
expr = canonicalize_ec_expression(expr, opcintype, collation);
636636

637-
/*
638-
* Get the precise set of nullable relids appearing in the expression.
639-
*/
640-
expr_relids = pull_varnos((Node *) expr);
641-
nullable_relids = bms_intersect(nullable_relids, expr_relids);
642-
643637
/*
644638
* Scan through the existing EquivalenceClasses for a match
645639
*/
@@ -716,6 +710,12 @@ get_eclass_for_sort_expr(PlannerInfo *root,
716710
if (newec->ec_has_volatile && sortref == 0) /* should not happen */
717711
elog(ERROR, "volatile EquivalenceClass has no sortref");
718712

713+
/*
714+
* Get the precise set of nullable relids appearing in the expression.
715+
*/
716+
expr_relids = pull_varnos((Node *) expr);
717+
nullable_relids = bms_intersect(nullable_relids, expr_relids);
718+
719719
newem = add_eq_member(newec, copyObject(expr), expr_relids,
720720
nullable_relids, false, opcintype);
721721

@@ -1171,9 +1171,9 @@ generate_join_implied_equalities(PlannerInfo *root,
11711171
}
11721172

11731173
/*
1174-
* Get all eclasses in common between inner_rel's relids and outer_relids
1174+
* Get all eclasses that mention both inner and outer sides of the join
11751175
*/
1176-
matching_ecs = get_common_eclass_indexes(root, inner_rel->relids,
1176+
matching_ecs = get_common_eclass_indexes(root, nominal_inner_relids,
11771177
outer_relids);
11781178

11791179
i = -1;

0 commit comments

Comments
 (0)
pFad - Phonifier reborn

Pfad - The Proxy pFad of © 2024 Garber Painting. All rights reserved.

Note: This service is not intended for secure transactions such as banking, social media, email, or purchasing. Use at your own risk. We assume no liability whatsoever for broken pages.


Alternative Proxies:

Alternative Proxy

pFad Proxy

pFad v3 Proxy

pFad v4 Proxy