Re: why the big difference on this explain analyze?

On 16 Mar 2002 at 17:19, Tom Lane wrote:

> "Dan Langille" <dan(at)langille(dot)org> writes:
> > The difference between the two SQL statements is the inclusion of
> > Ports_Check in the WHERE EXISTS select clause.
>
> Which caused it to do the wrong thing. I think you'll find this
> command set found_in_ports = TRUE in *every* row of Ports_Check.

Yes, it did. Not quite what I want either....

> Reason: the EXISTS clause no longer depends on the outer update,
> but evaluates to a constant TRUE. (Or possibly a constant FALSE,
> but that seems unlikely.)

Seems I'll have to keep searching for my speed improvement. Thanks for
pointing out that problem. cheers.
--
Dan Langille
The FreeBSD Diary - http://freebsddiary.org/ - practical examples