Ow Mun Heng <Ow.Mun.Heng@xxxxxxx> writes: > On Mon, 2008-08-25 at 10:18 -0400, Tom Lane wrote: >> I suppose code_id is varchar or some such? > Yep > After a few more investigation on the usefulness of the partial indexes, > I found that, it really isn't all that useful, perhaps some experts can > shed some light. I poked at that example a bit more earlier today, and found that 8.3 has a problem that's interfering with optimizing x IN ('y','z') type clauses when x is varchar. If you don't mind building a local copy, see if this patch helps you any: http://archives.postgresql.org/pgsql-committers/2008-08/msg00254.php regards, tom lane