From: Mindaugas Riauba <mind@bi.lt>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-performance@postgresql.org
Subject: Re: PostgreSQL strugling during high load
Date: Fri, 13 May 2005 17:10:01 +0300
Message-ID: <022901c557c5$73df1220$f20214ac@bite.lt> (raw)
References: <01cc01c557ba$a4fdb0b0$f20214ac@bite.lt>
<23217.1115991763@sss.pgh.pa.us>
> > ... So contents of database changes very fast. Problem is that when
> > pg_autovacuum does vacuum those changes slows down too much.
>
> The "vacuum cost" parameters can be adjusted to make vacuums fired
> by pg_autovacuum less of a burden. I haven't got any specific numbers
> to suggest, but perhaps someone else does.
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? WAL log
switch? One WAL file seems to last <1 minute.
And also in slow queries log only function call is shown. Maybe it is
possible
to get exact query which slows everything down in the serverlog?
Thanks,
Mindaugas
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To: pgsql-performance@postgresql.org
Cc: mind@bi.lt, tgl@sss.pgh.pa.us
Subject: Re: PostgreSQL strugling during high load
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