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From: Greg Smith <greg@2ndQuadrant.com>
To: pgsql-performance@postgresql.org
Subject: Re: buffercache/bgwriter
Date: Mon, 28 Mar 2011 02:02:42 -0400
Message-ID: <4D902482.9010705@2ndQuadrant.com> (raw)
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On 03/24/2011 05:19 AM, Uwe Bartels wrote:
> It would also be good to see how many buffers were written by backend 
> processes grouped by Buffer Access Strategy - to better distinguish 
> evil backend writes from wanted backend writes.

Since all these writes are being cached by the operating system, which 
strategy writes them out isn't that useful to track.  The only really 
"evil" type of writes are ones where the background writer doesn't 
absorb the fsync calls and the backends have to do that themselves.  And 
as of V9.1, that is something you can distinguish in pg_stat_bgwriter 
(and it's also less likely to happen, too)

-- 
Greg Smith   2ndQuadrant US    greg@2ndQuadrant.com   Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support  www.2ndQuadrant.us
"PostgreSQL 9.0 High Performance": http://www.2ndQuadrant.com/books




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