Re: Autoanalyze of the autovacuum daemon ...

From: Cédric Villemain <cedric(at)2ndquadrant(dot)com>
To: pgsql-hackers(at)postgresql(dot)org
Cc: Baptiste LHOSTE <blhoste(at)alaloop(dot)com>
Subject: Re: Autoanalyze of the autovacuum daemon ...
Date: 2012-10-31 12:44:20
Message-ID: 201210311344.24469.cedric@2ndquadrant.com
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Hello

this list is for PostgreSQL development purpose, better try at psql-general or
-admin.

> But the autoanalyze is not that effective for second kind.

if it is not running at all it is very probably because of threshold +
scale_factor and the size of the second kind of tables.

> We tried to reduce autovacuum_analyze_threshold (50 => 10) and
> autovacuum_analyze_scale_factor (0.1 => 0.005) for the second kind of
> tables (ALTER TABLE ... SET PARAMETERS ...) without any conclusive effect.
>
> We take a look at the relfrozenxid but our tables do not have a big value
> of relfrozenxid (< 10000000).
>
> Most of the time there is no autovacuum analyze query in the
> pg_stat_activity, althought we set the autovacuum_naptime to 15s to try to
> start new analyze task more often.

it will allow to check more often, not to start earlier.

> We do not understand why we can't obtain some improvments with previous
> changes. Did we do something wrong ?

Can you share the size of the tables ? (size , number of tuples, dead/live,
...) ? (please create a new thread in one of the other mailling-list)

--
Cédric Villemain +33 (0)6 20 30 22 52
http://2ndQuadrant.fr/
PostgreSQL: Support 24x7 - Développement, Expertise et Formation

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