Log Message:
-----------
Fix an oversight I introduced on 2003-12-28: find_nots/push_nots should
continue to recurse after eliminating a NOT-below-a-NOT, since the
contained subexpression will now be part of the top-level AND/OR structure
and so deserves to be simplified. The real-world impact of this is
probably minimal, since it'd require at least three levels of NOT to make
a difference, but it's still a bug.
Also remove some redundant tests for NULL subexpressions.
Modified Files:
--------------
pgsql/src/backend/optimizer/prep:
prepqual.c (r1.49 -> r1.50)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/prep/prepqual.c.diff?r1=1.49&r2=1.50)