Received: from localhost (unknown [200.46.204.184])
	by postgresql.org (Postfix) with ESMTP id DC4EC2E00CC
	for <pgsql-performance-postgresql.org@postgresql.org>;
	Fri, 21 Mar 2008 10:45:38 -0300 (ADT)
Received: from postgresql.org ([200.46.204.71])
	by localhost (mx1.hub.org [200.46.204.184]) (amavisd-maia, port 10024)
	with ESMTP id 79063-02 for
	<pgsql-performance-postgresql.org@postgresql.org>;
	Fri, 21 Mar 2008 10:45:23 -0300 (ADT)
X-Greylist: domain auto-whitelisted by SQLgrey-1.7.5
Received: from py-out-1112.google.com (py-out-1112.google.com
 [64.233.166.180])
	by postgresql.org (Postfix) with ESMTP id 422962E005C
	for <pgsql-performance@postgresql.org>;
	Fri, 21 Mar 2008 10:45:31 -0300 (ADT)
Received: by py-out-1112.google.com with SMTP id d37so2434639pye.29
	for <pgsql-performance@postgresql.org>;
	Fri, 21 Mar 2008 06:45:30 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=beta;
	h=domainkey-signature:received:received:message-id:date:from:sender:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references:x-google-sender-auth;
	bh=D+mDXsFuMN6yt6JUwSZoufDcMZhyAEvJOyjDTMUVB5c=;
	b=XjebSjdCh2ybI+YrbPBekMD0g2souPLmrx8KQ+AOO22EleoOvYV7cjULh+kAI9VuYvmIjISXYtXtAMlvFuTAbBjvJB78AVukR96xFhJV5CWBGGEk5IWj9KAZa9Q852re7ZscZV2QP1xXV3uNx4ns+zDtg9A3sz3iCDDXXmZY7ns=
DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta;
	h=message-id:date:from:sender:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references:x-google-sender-auth;
	b=ijtOUuhryQJAMZ8CeV8W37Hlxwdlc1vO+A2KjhKthRIOEeVGT+E4FR/eGhqoREk4fa0sIa4Vb6Wswp+RtgTX/PbaRPlq7dflKscaCr9sO+L6jHsaVX3bmhQo5dfUykBezuf6NA/5X/m6BxS1DOZc6frho1VuTIxhpkr3HGSA1D4=
Received: by 10.64.153.4 with SMTP id a4mr6501698qbe.15.1206107128869;
	Fri, 21 Mar 2008 06:45:28 -0700 (PDT)
Received: by 10.65.103.9 with HTTP; Fri, 21 Mar 2008 06:45:28 -0700 (PDT)
Message-ID: <669dc9710803210645m530b492cs6de98f215bcecb23@mail.gmail.com>
Date: Fri, 21 Mar 2008 14:45:28 +0100
From: "Laurent Raufaste" <analogue@glop.org>
To: pgsql-performance@postgresql.org
Subject: Re: PG writes a lot to the disk
In-Reply-To: <87prtoqkdk.fsf@oxford.xeocode.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
References: <669dc9710803190418g45002e87k19cb742579c1eeac@mail.gmail.com>
	<669dc9710803200348x64122249jd2ac5924d78a6da0@mail.gmail.com>
	<D960CB61B694CF459DCFB4B0128514C201E66F9E@exadv11.host.magwien.gv.at>
	<20080320105833.c539476d.wmoran@collaborativefusion.com>
	<10279.1206026439@sss.pgh.pa.us>
	<669dc9710803210349x764b2ec7k5aa95e33afefa926@mail.gmail.com>
	<87prtoqkdk.fsf@oxford.xeocode.com>
X-Google-Sender-Auth: 55a1c3b674dd140f
X-Virus-Scanned: Maia Mailguard 1.0.1
X-Spam-Status: No, hits=0.794 tagged_above=0 required=5 tests=AWL=0.794
X-Spam-Level: 
X-Archive-Number: 200803/422
X-Sequence-Number: 29376

2008/3/21, Gregory Stark <stark@enterprisedb.com>:
>
> Well that's true it does. But only once per row. So analyze would have set the
>  bit on every row. You could do the same thing with something ligter like
>  "select count(*) from <table>".

Well, the table has been analyzed, I did SELECT, PG write on the
table. That's a fact.

But it's also true (I juste tested it) that every file of a table is
modified by a SELECT COUNT.
>
>  Tom's thinking was that you would only expect a high update rate for a short
>  time until all those bits were set.
>
>  Slony's inserts, updates, and deletes count as updates to the table as well.
>

Slony is shut down when I'm testing.

-- 
Laurent Raufaste
<http://www.glop.org/>