Re: Massive performance differences

On Tue, 2005-03-15 at 12:18, Ragnar Hafstað wrote:
> On Tue, 2005-03-15 at 18:10 +0100, Andreas Hartmann wrote:
>
> > explain analyze select * from veranstaltung_original order by semester;
> >
> >   Sort  (cost=3054.08..3067.74 rows=5467 width=223) (actual
> > time=2568.10..2573.02 rows=5467 loops=1)
> >     Sort Key: semester
> >     ->  Seq Scan on veranstaltung_original  (cost=0.00..2714.67 rows=5467
> > width=223) (actual time=1936.68..2506.83 rows=5467 loops=1)
>                           ^^^^^^^
> isn't this value (1936.68) suspiscious for a seq scan ?
> can a lot of dead tuples cause this?
> maybe VACUUM FULL ANALYSE time ?

It's not unreasonable for the first run when the machine has to hit the
hard drives, but if it's that slow on subsequent reads, then there's
likely some problem.