Robert Haas <robertmhaas@gmail.com> writes:
> On Fri, Jul 17, 2009 at 10:21 AM, Tom Lane<tgl@sss.pgh.pa.us> wrote:
>> Actually, now that I think about it, the planner already has
>> datatype-specific knowledge about boolean equality (see
>> simplify_boolean_equality). It would take just a few more lines of code
>> there to recognize "x <> true" and "x <> false" as additional variant
>> spellings of the generic "x" or "NOT x" constructs. Not sure if it's
>> worth the trouble though; how many people really write such things?
> I don't know, but there's probably somebody. I probably did it myself
> a few times, when I was just starting out. If it's easy, it seems
> worth doing.
http://archives.postgresql.org/pgsql-committers/2009-07/msg00164.php
regards, tom lane