[postgis-users] Nested loop join = very bad performance
Mike Leahy
mgleahy at alumni.uwaterloo.ca
Mon Mar 29 19:53:41 PDT 2010
Mark/List,
I just replaced my postgresql.conf with the default copy that appears in
/etc/postgresql/8.4/main/ after a fresh install. The performance is pretty
much the same as before (maybe even about 400 ms worse than before).
Is there anything else I should try?
Mike
On Monday 29 March 2010 17:35:29 Mike Leahy wrote:
> Hi Mark,
>
> I don't recall making any changes...at least not until the error I
> encountered last week cropped up - but I think I reversed those changes (I
> will double- check tonight). But I think I have encountered performance
> problems with this query before on other systems - I had originally
> dismissed it as hardware limitations I was dealing in my testing system at
> the time. After recent hardware upgrades and after dealing with that
> specific bug, that's when the slow performance of this query really stood
> out.
>
> Mike
>
> On Monday 29 March 2010 07:53:50 Mark Cave-Ayland wrote:
> > Mike Leahy wrote:
> > > Is this something that should be looked into, or should I just
> > > incorporate the workaround of disabling nested loop joins into my code?
> >
> > I find that generally PostgreSQL is fairly good at its estimates unless
> > someone has already tried to tune the database. Have you changed any of
> > the settings in postgresql.conf from their defaults?
> >
> >
> > ATB,
> >
> > Mark.
>
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