Re: Serious issues with CPU usage - Mailing list pgsql-performance

From Tom Lane
Subject Re: Serious issues with CPU usage
Date
Msg-id 28675.1062806700@sss.pgh.pa.us
Whole thread Raw
In response to Serious issues with CPU usage  (<andris@neti.ee>)
Responses Re: Serious issues with CPU usage
List pgsql-performance
<andris@neti.ee> writes:
> i'm having _serious_ issues of postgres hogging up the CPU over time. A graph
> showing this can be seen at http://andri.estpak.ee/cpu0.png .

You really haven't shown us anything that would explain that graph ...
repeated UPDATEs will slow down a little until you vacuum, but not
by the ratio you seem to be indicating.  At least not if they're
indexscans.  If you've also got sequential-scan queries, and you're
doing many zillion updates between vacuums, the answer is to vacuum
more often.  A decent rule of thumb is to vacuum whenever you've updated
more than about 10% of the rows in a table since your last vacuum.

> A VACUUM FULL is a remedy to this problem, but a simple VACUUM isn't.

I find that odd; maybe there's something else going on here.  But you've
not given enough details to speculate.

            regards, tom lane

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