Matt,
> I recall seeing an email (I believe on this list) about how to improve
> performance of ISNULL's with some sort of tweak or trick. However, I
> can't find that email anywhere, and couldn't find it searching the
> maillist archives.
Easy. Create a partial index on NULLs:
CREATE INDEX idx_tablename_nulls ON tablename(columname)
WHERE columname IS NULL;
--
-Josh Berkus
Aglio Database Solutions
San Francisco