From: Donald Courtney <Donald.Courtney@Sun.COM>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-performance@postgresql.org
Subject: Re: PostgreSQL strugling during high load
Date: Thu, 19 May 2005 12:54:03 -0400
Message-ID: <428CC4AB.50906@sun.com> (raw)
In-Reply-To: <23517.1115993561@sss.pgh.pa.us>
References: <01cc01c557ba$a4fdb0b0$f20214ac@bite.lt>
<23217.1115991763@sss.pgh.pa.us>
<022901c557c5$73df1220$f20214ac@bite.lt>
<23517.1115993561@sss.pgh.pa.us>
Tom
Thanks for the post - I think I am getting this problem for
a synthetic workload at high connection loads. The whole
system seems to stop.
Can you give some examples on what to try out in the .conf file?
I tried
bgwriter_all_percent = 30, 10, and 3
Which I understand to mean 30%, 10% and 3% of the dirty pages should be
written out *between* checkpoints.
I didn't see any change in effect.
/regards
Don C.
Tom Lane wrote:
>"Mindaugas Riauba" <mind@bi.lt> writes:
>
>
>> It looks like that not only vacuum causes our problems. vacuum_cost
>>seems to lower vacuum impact but we are still noticing slow queries "storm".
>>We are logging queries that takes >2000ms to process.
>> And there is quiet periods and then suddenly 30+ slow queries appears in
>>log within the same second. What else could cause such behaviour?
>>
>>
>
>Checkpoints? You should ensure that the checkpoint settings are such
>that checkpoints don't happen too often (certainly not oftener than
>every five minutes or so), and make sure the bgwriter is configured
>to dribble out dirty pages at a reasonable rate, so that the next
>checkpoint doesn't have a whole load of stuff to write.
>
> regards, tom lane
>
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To: pgsql-performance@postgresql.org
Cc: Donald.Courtney@Sun.COM, tgl@sss.pgh.pa.us
Subject: Re: PostgreSQL strugling during high load
In-Reply-To: <428CC4AB.50906@sun.com>
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