Re: too many clog files - Mailing list pgsql-performance

From Tom Lane
Subject Re: too many clog files
Date
Msg-id 2257.1221068560@sss.pgh.pa.us
Whole thread Raw
In response to Re: too many clog files  ("Scott Marlowe" <scott.marlowe@gmail.com>)
Responses Re: too many clog files  ("Kevin Grittner" <Kevin.Grittner@wicourts.gov>)
List pgsql-performance
"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

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