From f502849d49a4744a8b6ce8abaf7af7c320c4ea0b Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Tue, 16 Apr 2024 11:22:39 -0400 Subject: Fix generation of EC join conditions at the wrong plan level. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit get_baserel_parampathinfo previously assumed without checking that the results of generate_join_implied_equalities "necessarily satisfy join_clause_is_movable_into". This turns out to be wrong in the presence of outer joins, because the generated clauses could include Vars that mustn't be evaluated below a relevant outer join. That led to applying clauses at the wrong plan level and possibly getting incorrect query results. We must check each clause's nullable_relids, and really the right thing to do is test join_clause_is_movable_into. However, trying to fix it that way exposes an oversight in equivclass.c: it wasn't careful about marking join clauses for appendrel children with the correct clause_relids. That caused the modified get_baserel_parampathinfo code to reject some clauses it still needs to accept. (See parallel commit for HEAD/v16 for more commentary about that.) Per bug #18429 from Benoît Ryder. This misbehavior existed for a long time before commit 2489d76c4, so patch v12-v15 this way. Discussion: https://postgr.es/m/18429-8982d4a348cc86c6@postgresql.org --- src/backend/optimizer/path/equivclass.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'src/backend/optimizer/path/equivclass.c') diff --git a/src/backend/optimizer/path/equivclass.c b/src/backend/optimizer/path/equivclass.c index e54da55924e..94387fdaca8 100644 --- a/src/backend/optimizer/path/equivclass.c +++ b/src/backend/optimizer/path/equivclass.c @@ -1465,6 +1465,21 @@ create_join_clause(PlannerInfo *root, rightem->em_nullable_relids), ec->ec_min_security); + /* + * If either EM is a child, force the clause's clause_relids to include + * the relid(s) of the child rel. In normal cases it would already, but + * not if we are considering appendrel child relations with pseudoconstant + * translated variables (i.e., UNION ALL sub-selects with constant output + * items). We must do this so that join_clause_is_movable_into() will + * think that the clause should be evaluated at the correct place. + */ + if (leftem->em_is_child) + rinfo->clause_relids = bms_add_members(rinfo->clause_relids, + leftem->em_relids); + if (rightem->em_is_child) + rinfo->clause_relids = bms_add_members(rinfo->clause_relids, + rightem->em_relids); + /* Mark the clause as redundant, or not */ rinfo->parent_ec = parent_ec; -- cgit v1.2.3