Re: Making Vars outer-join aware

 

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)

Thanks
Richard