Re: Followup Re: Performance question - Mailing list pgsql-admin

Is restarting postmaster on a regular basis necessary for performance?

----- Original Message -----
From: "Bob Smith" <bsmith@h-e.com>
To: "pgsql-admin" <pgsql-admin@postgresql.org>
Sent: Wednesday, March 05, 2003 2:20 PM
Subject: Followup Re: [ADMIN] Performance question


>
> OK, I seem to have fixed my own problem here again, sorry.  I restarted
> the postmaster, now _all_ queries are about 10x faster, and the first
> execution on a new connection is no longer significantly slower than
> the second.  The server (and the original postmaster) had been up for:
>
> 11:18AM  up 162 days, 17:48, 3 users, load averages: 0.57, 0.51, 0.51
>
> Maybe I should have a cron script restart postmaster every now and
> then, like once a week?
>
> Bob
>
> On Wednesday, Mar 5, 2003, at 10:11 US/Pacific, Bob Smith wrote:
>
> >
> > When I execute a query on a new connection, the performance is many
> > times slower than if the query is repeated.  In other words, if I
> > start psql, execute the query, then repeat it immediately, the second
> > time it takes only about 20% as long to execute.  Now here's the
> > confusing part, if I exit psql then start it up again, the same thing
> > will occur on the new connection as well, the first execution takes 5x
> > as long again.  I don't understand this, it would make sense to me
> > that the second execution being faster is due to disk caching on the
> > server, but then why is it slower again on every new connection?  Disk
> > caching should benefit all current and new connections until the cache
> > is flushed, which on this server shouldn't happen for a long time, the
> > load is light and it has lots of RAM.  Is Postgres doing some kind of
> > caching itself that lasts only for the life of one backend process?
> > If so, is there any way to make this caching persistent across
> > backends?
> >
> > Server particulars:
> >
> > Postgres 7.2.1, Mac OS X Server 10.1.5, dual 1GHz CPUs, 1.5GB memory
> >
> > Thanks!
> >
> > Bob Smith
> > Hammett & Edison, Inc.
> > bsmith@h-e.com
> >
> >
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