Re: FK index q'n

[Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>]

Tom Lane wrote:
> rihad <rihad(at)mail(dot)ru> writes:
> > Given this table:
> > CREATE TABLE foo (
> >      id integer primary key,
> >      bar_id integer references bar (id)
> > );
> > and provided that bar.id is itself a PK, do I still need to create an 
> > index on bar_id if often doing queries like:
> > SELECT MIN(id) FROM foo WHERE bar_id IS NULL;
> 
> Now as far as the above-illustrated query goes, no simple index is going
> to help it, because IS NULL is not an indexable operation.

Unless you are on 8.3, that is.

-- 
Alvaro Herrera                 http://www.amazon.com/gp/registry/CTMLCN8V17R4
Y dijo Dios: "Que sea Satanás, para que la gente no me culpe de todo a mí."
"Y que hayan abogados, para que la gente no culpe de todo a Satanás"