To: "Scott Marlowe" <scott.marlowe@gmail.com>
cc: "Kevin Grittner" <Kevin.Grittner@wicourts.gov>,
 alvherre@commandprompt.com,
	duanlg@nec-as.nec.com.cn, pgsql-performance@postgresql.org,
	"Matt Smiley" <mss@rentrak.com>
Subject: Re: too many clog files 
In-reply-to: <dcc563d10809101018u1f77199bpcc134121d7d040ad@mail.gmail.com> 
References: <48C5CC04.D078.0028.0@rentrak.com>
	<48C6F7A5.D078.0028.0@rentrak.com>
	<48C79A55.EE98.0025.0@wicourts.gov>
	<dcc563d10809101018u1f77199bpcc134121d7d040ad@mail.gmail.com>
Comments: In-reply-to "Scott Marlowe" <scott.marlowe@gmail.com>
	message dated "Wed, 10 Sep 2008 11:18:02 -0600"
Date: Wed, 10 Sep 2008 13:42:40 -0400
Message-ID: <2257.1221068560@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

"Scott Marlowe" <scott.marlowe@gmail.com> writes:
> On Wed, Sep 10, 2008 at 8:58 AM, Kevin Grittner
> <Kevin.Grittner@wicourts.gov> wrote:
>> Some of my high-volume databases don't quite go back to 0000, but this
>> does seem to be a problem.  I have confirmed that VACUUM FREEZE on all
>> but template0 (which doesn't allow connections) does not clean them
>> up.  No long running transactions are present.

> I have a pretty high volume server that's been online for one month
> and it had somewhere around 53, going back in order to 0000, and it
> was recently vacuumdb -az 'ed. Running another one.  No long running
> transactions, etc...

The expected behavior (in 8.2 and newer) is to maintain about
autovacuum_freeze_max_age transactions' worth of clog; which is to say
about 50MB at the default settings.  If you've got significantly more
than that then we should look more closely.

I don't remember what the truncation rule was in 8.1, so I can't speak
to the OP's complaint.

			regards, tom lane