Apologies if this is old news, but pg_autovacuum in 8.0.x has the bad habit
of SEGVing and exiting when a table gets dropped out from under it. This
creates problems if you rely on pg_autovacuum for the bulk of your vacuuming
as it forgets it's statistics when it is restarted and so will skip some
desireable vacuums.
I have a patch for this that should apply against any 8.0.x if there is any
interest.
I looked at the new autovacuum in 8.1 and it appears from casual inspection
not to have the same problem.
-dg
--
David Gould daveg(at)sonic(dot)net
If simplicity worked, the world would be overrun with insects.