Message-ID: <4E9354D2.8010608@peak6.com>
Date: Mon, 10 Oct 2011 15:25:54 -0500
From: Shaun Thomas <sthomas@peak6.com>
Reply-To: <sthomas@peak6.com>
Organization: Peak6
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To: alexandre - aldeia digital <adaldeia@gmail.com>
CC: undisclosed-recipients:;, <pgsql-performance@postgresql.org>
Subject: Re: Adding more memory = hugh cpu load
References: <4E92F294.9010405@gmail.com> <4E92FB87.1030703@peak6.com>
	<4E932BFC.7070007@gmail.com>
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On 10/10/2011 12:31 PM, alexandre - aldeia digital wrote:

> <2011-10-10 14:18:48 BRT >LOG: checkpoint complete: wrote 6885 buffers
> (1.1%); 0 transaction log file(s) added, 0 removed, 1 recycled;
> write=29.862 s, sync=28.466 s, total=58.651 s

28.466s sync time?! That's horrifying. At this point, I want to say the 
increase in effective_cache_size or shared_buffers triggered the planner 
to change one of your plans significantly enough it's doing a ton more 
disk IO and starving out your writes. Except you said you changed it 
back and it's still misbehaving.

This also reminds me somewhat of an issue Greg mentioned a while back 
with xlog storms in 9.0 databases. I can't recall how he usually "fixed" 
these, though.

-- 
Shaun Thomas
OptionsHouse | 141 W. Jackson Blvd. | Suite 800 | Chicago IL, 60604
312-676-8870
sthomas@peak6.com

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