Received: from localhost (unknown [200.46.204.183])
	by mail.postgresql.org (Postfix) with ESMTP id 2A9E964FEB3
	for <pgsql-performance-postgresql.org@mail.postgresql.org>;
	Wed, 17 Dec 2008 12:57:04 -0400 (AST)
Received: from mail.postgresql.org ([200.46.204.86])
	by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024)
	with ESMTP id 12279-06
	for <pgsql-performance-postgresql.org@mail.postgresql.org>;
	Wed, 17 Dec 2008 12:56:58 -0400 (AST)
X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6
Received: from rv-out-0506.google.com (rv-out-0506.google.com
 [209.85.198.235])
	by mail.postgresql.org (Postfix) with ESMTP id B6F8464FD71
	for <pgsql-performance@postgresql.org>;
	Wed, 17 Dec 2008 12:56:57 -0400 (AST)
Received: by rv-out-0506.google.com with SMTP id b25so5369499rvf.43
	for <pgsql-performance@postgresql.org>;
	Wed, 17 Dec 2008 08:56:56 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma;
	h=domainkey-signature:received:received:message-id:date:from:to
	:subject:cc:in-reply-to:mime-version:content-type
	:content-transfer-encoding:content-disposition:references;
	bh=ELGLF553PS7+m4IdOIQeV1oDLxpvBNSp9lgJ1iuj9p4=;
	b=gDcoYT10cDsu8yNiGeWB2ox3Phayz+vQ9ONzlh3Attjy+qaK6Q/XonlNBzN+2kv37/
	f+g0+J3wDcz66FDH2QPnDOtKLDDI1WFs3CT8goaMSb0gti6wmZDK0vPJXjn4rRKH2hfT
	wtZX8bhQSEuGLwJgfze1suyAXM2/cjPCdXnc4=
DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma;
	h=message-id:date:from:to:subject:cc:in-reply-to:mime-version
	:content-type:content-transfer-encoding:content-disposition
	:references;
	b=f2+2/FeCqK8q/RI08ozKUz1FQRBV6ZTvx2pMUYot+kOoakzEx0MbZHuRQQH9NHp1dR
	ZlJKJ5poWBhrw5JC29AzKEu8jkYGxtV3ZQdX8+U9MtAMIR6+t/GRlW0Xr1FtMudwipd1
	hTjLY5vh5LZ2dKQPQTgPe4k5sZmfjC3SQqLAk=
Received: by 10.140.140.3 with SMTP id n3mr485367rvd.111.1229533016138;
	Wed, 17 Dec 2008 08:56:56 -0800 (PST)
Received: by 10.141.210.17 with HTTP; Wed, 17 Dec 2008 08:56:56 -0800 (PST)
Message-ID: <603c8f070812170856g7ae06d58q2f487bead5f7be15@mail.gmail.com>
Date: Wed, 17 Dec 2008 11:56:56 -0500
From: "Robert Haas" <robertmhaas@gmail.com>
To: "Jaime Casanova" <jcasanov@systemguards.com.ec>
Subject: Re: measure database contention
Cc: "psql performance list" <pgsql-performance@postgresql.org>
In-Reply-To: <3073cc9b0812170738v69e43d89r8d6dae87453b4993@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
References: <3073cc9b0812161132w3ae157a8n69e2b0cccea05ca2@mail.gmail.com>
	<603c8f070812170618g3116a90du94cbf102f0336d59@mail.gmail.com>
	<3073cc9b0812170738v69e43d89r8d6dae87453b4993@mail.gmail.com>
X-Virus-Scanned: Maia Mailguard 1.0.1
X-Spam-Status: No, hits=0 tagged_above=0 required=5 tests=none
X-Spam-Level: 
X-Archive-Number: 200812/164
X-Sequence-Number: 32200

> is the exact query... i think it will be removed later today because
> is a bad query anyway... but my fear is that something like happens
> even with good ones...
>
> maybe chekpoints could be the problem?
> i have 8.3.5 and condigured checkpoint_timeout in 15 minutes,
> chekpoint_segments 6 and checkpoint_completion_target to 0.5

Well, it might help if you could provide the query, and the EXPLAIN output.

Unless the query is updating data (rather than just retrieving it),
checkpoints shouldn't be involved (I think).

...Robert