From 0d44d5960167a824a19c36459c2cf9937e4fa249 Mon Sep 17 00:00:00 2001 From: Yuya Watari Date: Mon, 5 Sep 2022 17:17:13 +0900 Subject: [PATCH v8 2/3] Revert one of the optimizations This commit reverts one of our optimizations. This function enumerates EquivalenceMembers in the given EquivalenceClass and returns true if there is a chance of merging. This check is accomplished by finding EMs where "bms_overlap(cur_em->em_relids, relids)" is false. In most cases, we reach such EMs early in the loop. Therefore, performing our newly introduced optimization technique is excessive here, and we revert the change. --- src/backend/optimizer/path/equivclass.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/src/backend/optimizer/path/equivclass.c b/src/backend/optimizer/path/equivclass.c index 8c9d4a4c3f..156a984014 100644 --- a/src/backend/optimizer/path/equivclass.c +++ b/src/backend/optimizer/path/equivclass.c @@ -3250,8 +3250,8 @@ eclass_useful_for_merging(PlannerInfo *root, EquivalenceClass *eclass, RelOptInfo *rel) { - Bitmapset *matching_ems; Relids relids; + int i; Assert(!eclass->ec_merged); @@ -3282,15 +3282,18 @@ eclass_useful_for_merging(PlannerInfo *root, if (bms_is_subset(eclass->ec_relids, relids)) return false; - /* Find the EquivalenceMember for relids */ - matching_ems = get_ecmember_indexes(root, eclass, relids, false, false); + /* To join, we need a member not in the given rel */ + i = -1; + while ((i = bms_next_member(eclass->ec_nonchild_indexes, i)) >= 0) + { + EquivalenceMember *cur_em = + list_nth_node(EquivalenceMember, root->eq_members, i); - /* - * If there are any other non-child members besides matching_ems then we - * have a chance at merging. - */ - if (bms_nonempty_difference(eclass->ec_nonchild_indexes, matching_ems)) - return true; + Assert(!cur_em->em_is_child); /* ignore children here */ + + if (!bms_overlap(cur_em->em_relids, relids)) + return true; + } return false; } -- 2.35.3.windows.1