On Wed, Jun 13, 2001 at 10:03:24AM -0400, Bruce Momjian wrote:
> > > select x from a where v in (select v from b)
> > > select x from a where exists (select 1 from b where a.v = b.v)
> >
> > The latter should be faster than the former on every relational database
> > system.
>
> That surprises me because the subquery is a correlated subquery which
> are usually slower on other databases that normal subqueries.
To be honest I didn't notice that. :-)
I was just talking about the difference with IN (where you have to compute
the complete result set) and EXISTS where you just look for one match.
Michael
--
Michael Meskes
Michael@Fam-Meskes.De
Go SF 49ers! Go Rhein Fire!
Use Debian GNU/Linux! Use PostgreSQL!
