On Wed, 4 Jul 2007 18:04:35 -0400 Alvaro Herrera wrote:
> Most likely it is worried about XID wraparound, and those are precisely > the tables that need urgent vacuumed because they haven't been vacuumed > in a long time.
No, autovacuum is doing this with every run. Beside this, the database has only some 10k changes per day. The wraparound was my first idea, but i don't see a reason, why this should be happen with every autovacuum run.
Did you check freeze_max_age values in the pg_autovacuum table ? A very small value can trigger XID wraparound related VACUUMs in every run.