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/util/relnode.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) (limited to 'src/backend/optimizer/util/relnode.c') diff --git a/src/backend/optimizer/util/relnode.c b/src/backend/optimizer/util/relnode.c index 7758a49fa4c..380ce9fc9a4 100644 --- a/src/backend/optimizer/util/relnode.c +++ b/src/backend/optimizer/util/relnode.c @@ -1264,6 +1264,7 @@ get_baserel_parampathinfo(PlannerInfo *root, RelOptInfo *baserel, ParamPathInfo *ppi; Relids joinrelids; List *pclauses; + List *eqclauses; double rows; ListCell *lc; @@ -1297,14 +1298,24 @@ get_baserel_parampathinfo(PlannerInfo *root, RelOptInfo *baserel, } /* - * Add in joinclauses generated by EquivalenceClasses, too. (These - * necessarily satisfy join_clause_is_movable_into.) + * Add in joinclauses generated by EquivalenceClasses, too. In principle + * these should always satisfy join_clause_is_movable_into; but if we are + * below an outer join the clauses might contain Vars that should only be + * evaluated above the join, so we have to check. */ - pclauses = list_concat(pclauses, - generate_join_implied_equalities(root, - joinrelids, - required_outer, - baserel)); + eqclauses = generate_join_implied_equalities(root, + joinrelids, + required_outer, + baserel); + foreach(lc, eqclauses) + { + RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc); + + if (join_clause_is_movable_into(rinfo, + baserel->relids, + joinrelids)) + pclauses = lappend(pclauses, rinfo); + } /* Estimate the number of rows returned by the parameterized scan */ rows = get_parameterized_baserel_size(root, baserel, pclauses); -- cgit v1.2.3