Message-ID: <4C92645A.1040208@agliodbs.com>
Date: Thu, 16 Sep 2010 11:39:22 -0700
From: Josh Berkus <josh@agliodbs.com>
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To: pgsql-performance@postgresql.org
Subject: Re: Where does data in pg_stat_user_tables come from?
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> It's been pure nonsense in this thread.  Please show an example of
> what's not working.

1) Init a postgresql 8.3 with autovacuum disabled.

2) Load a backup of a database into that PostgreSQL.

3) Check pg_stat_user_tables.  n_live_tup for all tables will be 0.

4) VACUUM ANALYZE the whole database.

5) n_live_tup will *still* be 0.  Whereas reltuples in pg_class will be
reasonable accurate.

> Um ... it updates the last_autovacuum and last_autoanalyze columns,
> but the others are not its responsibility.

Right. I'm contending that ANALYZE *should* update those columns.
Current behavior is unintuitive and makes the stats in
pg_stat_user_tables almost useless, since you can never get even
approximately a coherent snapshot of data for all tables.

-- 
                                  -- Josh Berkus
                                     PostgreSQL Experts Inc.
                                     http://www.pgexperts.com