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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2012-10-03 13:37:53 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2012-10-03 13:37:53 -0400 |
| commit | 1f91c8ca1d2edc66c688ee719eded79ecd0e8f1b (patch) | |
| tree | 81431c90c1f5eb62ad847492881f56e0158781da | |
| parent | fe3b5eb08a16c391478e305bd9ea40f4f5979689 (diff) | |
| download | postgresql-1f91c8ca1d2edc66c688ee719eded79ecd0e8f1b.tar.gz postgresql-1f91c8ca1d2edc66c688ee719eded79ecd0e8f1b.zip | |
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.
| -rw-r--r-- | src/backend/utils/adt/selfuncs.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c index 2ab26dea290..61100aec4ae 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 |