From 1f91c8ca1d2edc66c688ee719eded79ecd0e8f1b Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Wed, 3 Oct 2012 13:37:53 -0400 Subject: [PATCH] Avoid planner crash/Assert failure with joins to unflattened subqueries. examine_simple_variable supposed that any RTE_SUBQUERY rel it gets pointed at must have been planned already. However, this isn't a safe assumption because we must do selectivity estimation while generating indexscan paths, and that code might look at join clauses involving a rel that the loop in set_base_rel_sizes() hasn't reached yet. The simplest fix is to play dumb in such a situation, that is give up trying to extract any stats for the Var. This could possibly be improved by making a separate pass over the RTE list to plan each unflattened subquery before we start the main planning work --- but that would be pretty invasive and it doesn't seem worth it, for now at least. (We couldn't just break set_base_rel_sizes() into two loops: the prescan would need to handle all subquery rels in the query, not only those in the current join subproblem.) This bug was introduced in commit 1cb108efb0e60d87e4adec38e7636b6e8efbeb57, although I think that subsequent changes may have exposed it more than it was originally. Per bug #7580 from Maxim Boguk. --- src/backend/utils/adt/selfuncs.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c index 2ab26dea29..61100aec4a 100644 --- a/src/backend/utils/adt/selfuncs.c +++ b/src/backend/utils/adt/selfuncs.c @@ -4518,8 +4518,10 @@ examine_simple_variable(PlannerInfo *root, Var *var, */ rel = find_base_rel(root, var->varno); - /* Subquery should have been planned already */ - Assert(rel->subroot && IsA(rel->subroot, PlannerInfo)); + /* If the subquery hasn't been planned yet, we have to punt */ + if (rel->subroot == NULL) + return; + Assert(IsA(rel->subroot, PlannerInfo)); /* * Switch our attention to the subquery as mangled by the planner. It -- 2.40.0