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Re: concurrent IO in postgres?

From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
To: "John W Strange" <john(dot)w(dot)strange(at)jpmchase(dot)com>, "wozniak(at)lanl(dot)gov" <wozniak(at)lanl(dot)gov>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: concurrent IO in postgres?
Date: 2010-12-23 19:02:59
Message-ID: 4D1348830200002500038A88@gw.wicourts.gov (view raw or flat)
Thread:
Lists: pgsql-performance
John W Strange <john(dot)w(dot)strange(at)jpmchase(dot)com> wrote:
 
> Typically my problem is that the large queries are simply CPU
> bound.
 
Well, if your bottleneck is CPU, then you're obviously not going to
be driving another resource (like disk) to its limit.  First,
though, I want to confirm that your "CPU bound" case isn't in the
"I/O Wait" category of CPU time.  What does `vmstat 1` show while
you're CPU bound?
 
If it's not I/O Wait time, then you need to try to look at the
queries involved.  If you're not hitting the disk because most of
the active data is cached, that would normally be a good thing. 
What kind of throughput are you seeing?  Do you need better?
 
http://wiki.postgresql.org/wiki/SlowQueryQuestions
 
-Kevin

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