Re: wrong query result due to wang plan

 

It occurs to me that we can leverage JoinDomain to tell if we are below
the nullable side of a higher-level outer join if the clause is not an
outer-join clause.  If we are belew outer join, the current JoinDomain
is supposed to be a proper subset of top JoinDomain.  Otherwise the
current JoinDomain must be equal to top JoinDomain.  And that leads to a
fix as code changes below.

--- a/src/backend/optimizer/plan/initsplan.c
+++ b/src/backend/optimizer/plan/initsplan.c
@@ -2269,8 +2269,16 @@ distribute_qual_to_rels(PlannerInfo *root, Node *clause,
     }
     else
     {
-        /* eval at join domain level */
-        relids = bms_copy(jtitem->jdomain->jd_relids);
+        JoinDomain *top_jdomain =
+            linitial_node(JoinDomain, root->join_domains);
+
+        /*
+         * eval at original syntactic level if we are below an outer join,
+         * otherwise eval at join domain level, which is actually the top
+         * of tree
+         */
+        relids = jtitem->jdomain == top_jdomain ?
+                 bms_copy(jtitem->jdomain->jd_relids) : bms_copy(qualscope);


Thanks
Richard