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Message-ID: <022901c557c5$73df1220$f20214ac@bite.lt>
From: "Mindaugas Riauba" <mind@bi.lt>
To: "Tom Lane" <tgl@sss.pgh.pa.us>
Cc: <pgsql-performance@postgresql.org>
References: <01cc01c557ba$a4fdb0b0$f20214ac@bite.lt>
	<23217.1115991763@sss.pgh.pa.us>
Subject: Re: PostgreSQL strugling during high load 
Date: Fri, 13 May 2005 17:10:01 +0300
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> > ... 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