Re: stats collector process high CPU utilization

From: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: minshall(at)intellicon(dot)biz, pgsql-performance(at)postgresql(dot)org
Subject: Re: stats collector process high CPU utilization
Date: 2007-02-09 14:24:59
Message-ID: 20070209142459.GB4253@alvh.no-ip.org
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Tom Lane wrote:
> minshall(at)intellicon(dot)biz writes:
> > While exploring this problem, I've noticed that one of the frequent insert
> > processes creates a few temporary tables to do post-processing. Is it
> > possible that the stats collector is getting bloated with stats from these
> > short-lived temporary tables? During periods of high activity it could be
> > creating temporary tables as often as two per second.
>
> Hmmm ... that's an interesting point, but offhand I don't see why it'd
> cause more of a problem in 8.2 than 8.1. Alvaro, any thoughts?

No idea. I do have a very crude piece of code to read a pgstat.stat
file and output some info about what it finds (table OIDs basically
IIRC). Maybe it can be helpful to examine what's in the bloated stat
file.

Regarding temp tables, I'd think that the pgstat entries should be
getting dropped at some point in both releases. Maybe there's a bug
preventing that in 8.2?

--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support

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