Ow Mun Heng <Ow(dot)Mun(dot)Heng(at)wdc(dot)com> 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