From 8f2ec8cc7e3de918988a49302dddc64deca16c02 Mon Sep 17 00:00:00 2001 From: David Rowley Date: Mon, 19 Jun 2023 13:01:29 +1200 Subject: Don't use partial unique indexes for unique proofs in the planner Here we adjust relation_has_unique_index_for() so that it no longer makes use of partial unique indexes as uniqueness proofs. It is incorrect to use these as the predicates used by check_index_predicates() to set predOK makes use of not only baserestrictinfo quals as proofs, but also qual from join conditions. For relation_has_unique_index_for()'s case, we need to know the relation is unique for a given set of columns before any joins are evaluated, so if predOK was only set to true due to some join qual, then it's unsafe to use such indexes in relation_has_unique_index_for(). The final plan may not even make use of that index, which could result in reading tuples that are not as unique as the planner previously expected them to be. Bug: #17975 Reported-by: Tor Erik Linnerud Backpatch-through: 11, all supported versions Discussion: https://postgr.es/m/17975-98a90c156f25c952%40postgresql.org --- src/backend/optimizer/plan/analyzejoins.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) (limited to 'src/backend/optimizer/plan/analyzejoins.c') diff --git a/src/backend/optimizer/plan/analyzejoins.c b/src/backend/optimizer/plan/analyzejoins.c index 7ea6e26fecd..34efeee93f9 100644 --- a/src/backend/optimizer/plan/analyzejoins.c +++ b/src/backend/optimizer/plan/analyzejoins.c @@ -600,9 +600,9 @@ rel_supports_distinctness(PlannerInfo *root, RelOptInfo *rel) /* * For a plain relation, we only know how to prove uniqueness by * reference to unique indexes. Make sure there's at least one - * suitable unique index. It must be immediately enforced, and if - * it's a partial index, it must match the query. (Keep these - * conditions in sync with relation_has_unique_index_for!) + * suitable unique index. It must be immediately enforced, and not a + * partial index. (Keep these conditions in sync with + * relation_has_unique_index_for!) */ ListCell *lc; @@ -610,8 +610,7 @@ rel_supports_distinctness(PlannerInfo *root, RelOptInfo *rel) { IndexOptInfo *ind = (IndexOptInfo *) lfirst(lc); - if (ind->unique && ind->immediate && - (ind->indpred == NIL || ind->predOK)) + if (ind->unique && ind->immediate && ind->indpred == NIL) return true; } } -- cgit v1.2.3