From: | Josh Berkus <josh(at)agliodbs(dot)com> |
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To: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Where does data in pg_stat_user_tables come from? |
Date: | 2010-09-16 18:39:22 |
Message-ID: | 4C92645A.1040208@agliodbs.com |
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Lists: | pgsql-performance |
> 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
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