I already found the answer, sorry... my mistake for not checking the 8.2.0 release note first. It turns out that such behaviour is expected in 8.2.0, i.e. autovacuum process no longer add an entry to the server log.
http://www.postgresql.org/docs/current/static/release-8-2.html But then, another question arises... how could I know whether it's working if it does not add any entry to the log? an excerpt from the above link: "pg_stat_activity now shows autovacuum activity." I expected to see a new process showing up in pgAdmin's Server Status window while autovacuum is running, but there was none. ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
