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Re: postgres: 100% CPU utilization

From: Scott Marlowe <smarlowe(at)g2switchworks(dot)com>
To: Sergey Tsukinovsky <Sergey(dot)Tsukinovsky(at)cryptologic(dot)com>
Cc: Ron <rjpeace(at)earthlink(dot)net>, Mario Weilguni <mweilguni(at)sime(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: postgres: 100% CPU utilization
Date: 2007-04-26 22:50:27
Message-ID: 1177627827.15085.87.camel@state.g2switchworks.com (view raw or flat)
Thread:
Lists: pgsql-performance
On Tue, 2007-04-24 at 10:30, Sergey Tsukinovsky wrote:
> Thanks for this reply, Ron.
> This is almost what I was looking for.
> 
> While the upgrade to the latest version is out of the question (which
> unfortunately for me became the subject of this discussion) still, I was
> looking for the ways to improve the performance of the 7.0.2 version. 
> 
> Extensive use of vacuum was almost obvious, though I was hoping to get
> some more tips from postrges gurus (or dinosaurs, if you want).
> 
> Anyways, the 8.2.4 was not performing so well without auto-vacuum. It
> ramped up to 50% of CPU usage in 2 hours under the load.
> With the auto-vacuum ON I've got what I really need and thus I know what
> to do next.

Could you give us a better picture of how you were testing 8.2.4?  My
guess is that you were doing something that seemed right to you, but was
working against yourself, like constant vacuum fulls and getting index
bloat, or something else.  

Why were you trying to not use autovacuum, btw?  I've found it to be
quite capable, with only a few situations (high speed queueing) where I
needed to manually schedule vacuums.  And I've never seen a situation
since about 7.4 where regular full vacuums were required.

> Just for the record - the hardware that was used for the test has the
> following parameters:
> AMD Opteron 2GHZ
> 2GB RAM
> LSI Logic SCSI

Nice hardware.  I'd really like to hear the logic behind your statement
that upgrading to 8.1 or 8.2 is out of the question.

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