Date: Thu, 18 Sep 2014 12:33:38 +0200
From: Andres Freund <andres@2ndquadrant.com>
To: Dev Kumkar <devdas.kumkar@gmail.com>
Cc: Adrian Klaver <adrian.klaver@aklaver.com>,
 "pgsql-general@postgresql.org" <pgsql-general@postgresql.org>,
 pgsql-sql@postgresql.org
Subject: Re: [SQL] pg_multixact issues
Message-ID: <20140918103338.GF17265@alap3.anarazel.de>
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On 2014-09-18 14:41:07 +0530, Dev Kumkar wrote:
> On Thu, Sep 18, 2014 at 2:41 AM, Adrian Klaver <adrian.klaver@aklaver.com>
> wrote:
> 
> >
> > Aaah, hit enter too soon. Also see the other changes under Changes that
> > apply to multixact in 9.3.5
> 
> 
> Thanks for sharing same. Found this one interesting "Truncate pg_multixact
> during checkpoints, not during VACUUM (Álvaro Herrera)" and also other
> changes. But am not sure are you suggesting to move to 9.3.5 ?

I don't think that's relevant for you.

Did you upgrade the database using pg_upgrade?

> Actually looking for some guidelines on truncating pg_multixact at this
> situation.
> 
> - Do I need to run vaccum manually here and then the pg_multixact can be
> truncated?
> - Actually looking out for some hints wherein can know the current
> pg_multixact/members which are active and which one are stale which can be
> truncated? Is there any query to find this information?
> 
> pg_class.relminmxid can be referred but should I change the value of
> autovacuum_multixact_freeze_max_age which defaults to 400 million
> multixacts, setting this value to lower limits would help in cleaning up
> pg_multixact?

Can you show pg_controldata output and the output of 'SELECT oid,
datname, relfrozenxid, age(relfrozenxid), relminmxid FROM pg_database;'?

Greetings,

Andres Freund

-- 
 Andres Freund	                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services


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