Re: [SQL] pg_multixact issues

On 2014-09-18 14:41:07 +0530, Dev Kumkar wrote:
> On Thu, Sep 18, 2014 at 2:41 AM, Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)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/
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