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Message-ID: <4C750E51.6080409@ca.afilias.info>
Date: Wed, 25 Aug 2010 08:36:33 -0400
From: Brad Nicholson <bnichols@ca.afilias.info>
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To: pgsql-admin@postgresql.org
Subject: Re: last_autovacuum & last_autoanalyze showing NULL
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  On 10-08-25 03:30 AM, Gnanakumar wrote:
> Hi,
>
> Our production server is running PostgreSQL v8.2.3 on RHEL5.  Autovacuum
> daemon is also running in the server.
>
> A brief background on my use case:  We heavily use a table for storing of
> data temporarily inside PostgreSQL functions.  Eventually, there will not be
> any record in the table.  Because this table is used heavily, I usually keep
> tab of this particular table in "pg_stat_user_tables", so that disk space is
> within control.
>
> Recently, I noticed that "last_autovacuum" and "last_autoanalyze" column for
> this table showing a<NULL>  value.  My question here is, what
> condition/scenario would make this column to update to<NULL>  value by
> autovacuum?  I can add one more point here, which I remember, that is I
> performed a TRUNCATE on this table just before.  I believe that this is not
> because of TRUNCATE  TABLE?

Truncate should not affect those values.

Has your Postgres instance crashed or been restarted with immediate mode 
since the last vacuum?  This will cause the autovacuum information to be 
null.

Also, are you sure that autovacuum has processed these tables at least once?

-- 
Brad Nicholson  416-673-4106
Database Administrator, Afilias Canada Corp.