Michael Goldner <mike.goldner@comcast.net> writes:
> Could autovacuum be using enough memory so that postgres cannot handle
> the insert of the large row?
No. You might be having locking problems, though --- have you looked
into pg_locks to see if anything is blocked on a lock? Those "INSERT
waiting" processes certainly look like they are so blocked.
There was a thread just yesterday
http://archives.postgresql.org/pgsql-performance/2006-10/msg00190.php
suggesting that 8.1's autovacuum might have some as-yet-undetermined
locking issues, but that's only speculation at this point. If you can
get some evidence showing that it's really happening, I'm all ears...
regards, tom lane