Fix recursion into previously planned sub-query in examine_simple_variable.

This code was looking at the sub-Query tree as seen in the parent query's
RangeTblEntry; but that's the pristine parser output, and what we need to
look at is the tree as it stands at the completion of planning.  Otherwise
we might pick up a Var that references a subquery that got flattened and
hence has no RelOptInfo in the subroot.  Per report from Peter Geoghegan.

diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index 3e8467995634e607efe91e34692c7c24187be1cb..8ceea820bdc4eb2e6c737c2f98eb1f0bf6fa034b 100644 (file)
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -4382,6 +4382,17 @@ examine_simple_variable(PlannerInfo *root, Var *var,
                /* Subquery should have been planned already */
                Assert(rel->subroot && IsA(rel->subroot, PlannerInfo));
 
+               /*
+                * Switch our attention to the subquery as mangled by the planner.
+                * It was okay to look at the pre-planning version for the tests
+                * above, but now we need a Var that will refer to the subroot's
+                * live RelOptInfos.  For instance, if any subquery pullup happened
+                * during planning, Vars in the targetlist might have gotten replaced,
+                * and we need to see the replacement expressions.
+                */
+               subquery = rel->subroot->parse;
+               Assert(IsA(subquery, Query));
+
                /* Get the subquery output expression referenced by the upper Var */
                ste = get_tle_by_resno(subquery->targetList, var->varattno);
                if (ste == NULL || ste->resjunk)