Re: planner with index scan cost way off actual cost,

From: Guillaume Cottenceau <gc(at)mnc(dot)ch>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: planner with index scan cost way off actual cost,
Date: 2006-03-21 13:03:19
Message-ID: 87acbkkl0o.fsf@meuh.mnc.lan
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"Jim C. Nasby" <jnasby 'at' pervasive.com> writes:

> On Tue, Mar 21, 2006 at 10:40:45PM +1200, Mark Kirkwood wrote:
> > I was going to recommend higher - but not knowing what else was running,
> > kept it to quite conservative :-)... and given he's running java, the
> > JVM could easily eat 512M all by itself!
>
> Oh, didn't pick up on java being in the mix. Yeah, it can be a real pig.
> I think people often place too much emphasis on having a seperate
> application server, but in the case of java you often have no choice.

Fortunately the servers use 2G or 4G of memory, only my test
machine had 1G, as I believe I precised in a message; so I'm
definitely going to use Mark's advices to enlarge a lot the
shared buffers. Btw, what about sort_mem? I have seen it only
little referenced in the documentation.

Also, I'd still be interested in comments on the result of pmap
showing around 450M of "private memory" used by pg, if anyone can
share insight about it. Though most people seem freebsd-oriented,
and this might be very much linux-centric.

--
Guillaume Cottenceau

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