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Re: CPU utilization vs. IO wait, shared buffers?

From: Alan Hodgson <ahodgson(at)simkin(dot)ca>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: CPU utilization vs. IO wait, shared buffers?
Date: 2008-10-30 21:48:58
Message-ID: 200810301448.58941@hal.medialogik.com (view raw or flat)
Thread:
Lists: pgsql-performance
On Thursday 30 October 2008, "Oliver Johnson" <oliverjjohnson(at)gmail(dot)com> 
wrote:
> Another thing to note, we have VACUUM ANALYZE running on an hourly
> interval and the switch from CPU to IO wait appears to always coincide
> with a vacuum.
>
> What might cause this shift?

The extra disk access caused by vacuum? That seems pretty obvious.

Use auto-vacuum. There's no reason to vacuum your entire database every hour 
(doing so reads from disk the entirety of every table and index, and 
generates some write activity).

-- 
Alan

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