From: Jérôme BENOIS <benois@argia-engineering.fr>
To: Dave Dutcher <dave@tridecap.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: High CPU Load
Date: Thu, 14 Sep 2006 17:09:25 +0200
Message-ID: <1158246565.5226.59.camel@localhost.localdomain> (raw)
In-Reply-To: <004001c6d80e$bdef5bc0$8300a8c0@tridecap.com>
References: <004001c6d80e$bdef5bc0$8300a8c0@tridecap.com>
Hi Dave,
Le jeudi 14 septembre 2006 à 10:02 -0500, Dave Dutcher a écrit :
> > -----Original Message-----
> > From: pgsql-performance-owner@postgresql.org
> > [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of
> > Jérôme BENOIS
> >
> explain analyze select distinct
> > INTEGER_VALUE,DATE_VALUE,EI_ID,VALUE_TYPE,FLOAT_VALUE,ID,TEXT_
> > VALUE,CATEGORY_ID,STRING_VALUE,CATEGORYATTR_ID,NAME from (((
> > select distinct ei_id as EIID from mpng2_ei_attribute as
> > reqin1 where reqin1.CATEGORYATTR_ID = 0 AND reqin1.TEXT_VALUE
> > ilike '' and ei_id in ( select distinct ei_id as EIID from
> > mpng2_ei_attribute as reqin2 where reqin2.CATEGORYATTR_ID = 0
> > AND reqin2.TEXT_VALUE ilike '' and ei_id in ( select distinct
> > ei_id as EIID from mpng2_ei_attribute as reqin3 where
> > reqin3.NAME = '' AND reqin3.STRING_VALUE = '' ) ) ) ) ) as
> > req0 join mpng2_ei_attribute on req0.eiid =
> > mpng2_ei_attribute.ei_id order by ei_id asc;
>
>
> That is a lot of distinct's. Sorts are one thing that can really use up
> CPU. This query is doing lots of sorts, so its not surprising the CPU usage
> is high.
>
> On the subqueries you have a couple of cases where you say "... in (select
> distinct ...)" I don’t think the distinct clause is necessary in that case.
> I'm not a hundred percent sure, but you might want to try removing them and
> see if the query results are the same and maybe the query will execute
> faster.
Thanks for your advice, but the load was good with previous version of
postgres -> 7.4.6 on the same server and same datas, same application,
same final users ...
So we supect some system parameter, but which ?
With vmstat -s is showing a lot of "pages swapped out", have you an
idea ?
Thanls a lot,
--
Jérôme,
python -c "print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in 'sioneb@gnireenigne-aigra.rf'.split('@')])"
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To: pgsql-performance@postgresql.org
Cc: benois@argia-engineering.fr, dave@tridecap.com
Subject: Re: High CPU Load
In-Reply-To: <1158246565.5226.59.camel@localhost.localdomain>
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