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Re: too many clog files

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com>
Cc: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>, alvherre(at)commandprompt(dot)com, duanlg(at)nec-as(dot)nec(dot)com(dot)cn, pgsql-performance(at)postgresql(dot)org, "Matt Smiley" <mss(at)rentrak(dot)com>
Subject: Re: too many clog files
Date: 2008-09-10 17:42:40
Message-ID: 2257.1221068560@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-performance
"Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com> writes:
> On Wed, Sep 10, 2008 at 8:58 AM, Kevin Grittner
> <Kevin(dot)Grittner(at)wicourts(dot)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

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Subject: Re: too many clog files
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