Here's a rebase up to HEAD, mainly to get the cfbot back in sync as to what's the live patch.
Noticed another different behavior from previous. When we try to reduce JOIN_LEFT to JOIN_ANTI, we want to know if the join's own quals are strict for any Var that was forced null by higher qual levels. We do that by checking whether local_nonnullable_vars and forced_null_vars overlap. However, the same Var from local_nonnullable_vars and forced_null_vars may be labeled with different varnullingrels. If that is the case, currently we would fail to tell they actually overlap. As an example, consider 'b.i' in the query below
# explain (costs off) select * from a left join b on a.i = b.i where b.i is null; QUERY PLAN --------------------------- Hash Left Join Hash Cond: (a.i = b.i) Filter: (b.i IS NULL) -> Seq Scan on a -> Hash -> Seq Scan on b (6 rows)
