diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/optimizer/path/equivclass.c | 28 |
1 files changed, 5 insertions, 23 deletions
diff --git a/src/backend/optimizer/path/equivclass.c b/src/backend/optimizer/path/equivclass.c index 0b2e212b2bc..600fa1263a7 100644 --- a/src/backend/optimizer/path/equivclass.c +++ b/src/backend/optimizer/path/equivclass.c @@ -816,8 +816,6 @@ find_em_expr_usable_for_sorting_rel(PlannerInfo *root, EquivalenceClass *ec, { EquivalenceMember *em = lfirst(lc_em); Expr *em_expr = em->em_expr; - PathTarget *target = rel->reltarget; - ListCell *lc_target_expr; /* * We shouldn't be trying to sort by an equivalence class that @@ -851,30 +849,14 @@ find_em_expr_usable_for_sorting_rel(PlannerInfo *root, EquivalenceClass *ec, * As long as the expression isn't volatile then * prepare_sort_from_pathkeys is able to generate a new target entry, * so there's no need to verify that one already exists. + * + * While prepare_sort_from_pathkeys has to be concerned about matching + * up a volatile expression to the proper tlist entry, it doesn't seem + * valuable here to expend the work trying to find a match in the + * target's exprs since such a sort will have to be postponed anyway. */ if (!ec->ec_has_volatile) return em->em_expr; - - /* - * If, however, it's volatile, we have to verify that the - * equivalence member's expr is already generated in the - * relation's target (we do strip relabels first from both - * expressions, which is cheap and might allow us to match - * more expressions). - */ - while (em_expr && IsA(em_expr, RelabelType)) - em_expr = ((RelabelType *) em_expr)->arg; - - foreach(lc_target_expr, target->exprs) - { - Expr *target_expr = lfirst(lc_target_expr); - - while (target_expr && IsA(target_expr, RelabelType)) - target_expr = ((RelabelType *) target_expr)->arg; - - if (equal(target_expr, em_expr)) - return em->em_expr; - } } /* We didn't find any suitable equivalence class expression */ |