Re: Why is postgres autovacuuming a table that is never updated?

[Alvaro Herrera <alvherre(at)commandprompt(dot)com>]

Joseph S wrote:
> I'm running 8.2.6.  I have a log table that is always INSERTed to, and  
> no updates or deletes are ever run on.  For some reason the autovacuum  
> decided it needed to vacuum this table, and it is slowing down my  
> production server.

Perhaps it's because the table is close to Xid wraparound.  Please see

select age(relfrozenxid) from pg_class where oid = 'your-table'::regclass;

If the age exceeds max freeze age, then this is the cause.  (The 
freeze max age can come from the freeze_max_age param, or
autovacuum_freeze_max_age, or pg_autovacuum.freeze_max_age).

Hmm, maybe it's called max_freeze_age, I don't recall offhand.

Beware of the pg_autovacuum column being zero.

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.