Re: intersect performance (PG 7.1.3 vs 7.2)

d_nardini@btconnect.com writes:
> I'm running the following statement on a (development) Mac OS X (PG 7.2) 
> box and on a (production) RedHat 7.0 (PG 7.1.3) box. On the OS X it's 
> performing very well ... on RH it's VERY SLOW, with CPU utilization 
> hitting 90%+ (on OS X it hardly exceeds 2%).

Hmm.  Nested intersects are actually broken in 7.1.*,
cf.http://archives.postgresql.org/pgsql-bugs/2001-08/msg00064.php
Do you get the same results from both boxes?

> BTW - replacing 'intersect' 
> with 'union' in the SQL behaves the same.

In that case it might possibly be a different problem.  Do you get the
same EXPLAIN plan on both boxes?
        regards, tom lane