Fix bug introduced into indexable_outerrelids() by an ill-considered

"optimization".  When we find a potentially useful joinclause, we
have to add all its other required_relids to the result, not only the
other clause_relids.  They are different in the case of a joinclause
whose applicability has to be postponed due to outer join.  We have
to include the extra rels because otherwise, after best_inner_indexscan
masks the join rels with index_outer_relids, it will always fail to
find the joinclause as applicable.  Per report from Husam Tomeh.

diff --git a/src/backend/optimizer/path/indxpath.c b/src/backend/optimizer/path/indxpath.c
index bb6b73faf30d7a48a805e3fe4928b7474ba4588b..65eff98d0ae5b40588e74f8c1558c33ff8c46716 100644 (file)
--- a/src/backend/optimizer/path/indxpath.c
+++ b/src/backend/optimizer/path/indxpath.c
@@ -955,15 +955,13 @@ indexable_outerrelids(RelOptInfo *rel)
        /*
         * Examine each joinclause in the joininfo list to see if it matches any
         * key of any index.  If so, add the clause's other rels to the result.
-        * (Note: we consider only actual participants, not extraneous rels
-        * possibly mentioned in required_relids.)
         */
        foreach(l, rel->joininfo)
        {
                RestrictInfo *joininfo = (RestrictInfo *) lfirst(l);
                Relids  other_rels;
 
-               other_rels = bms_difference(joininfo->clause_relids, rel->relids);
+               other_rels = bms_difference(joininfo->required_relids, rel->relids);
                if (matches_any_index(joininfo, rel, other_rels))
                        outer_relids = bms_join(outer_relids, other_rels);
                else