Re: Removing const-false IS NULL quals and redundant IS NOT NULL quals

I also want to add notnullattnums for the UniqueKey stuff as well, by
comparing your implementation with mine,  I found you didn't consider
the NOT NULL generated by filter. After apply your patch:

create table a(a int);
explain (costs off) select * from a where a > 3 and a is null;
             QUERY PLAN             
-------------------------------------
 Seq Scan on a
   Filter: ((a IS NULL) AND (a > 3))
(2 rows)