<ogjunk-pgjedan@yahoo.com> writes:
> VACUUMing this DB takes about 30 minutes, and during that time the DB
> is pretty unresponsive, although the PG process is not using a lot of
> CPU (load ~ 1) nor memory (~20MB for the VACUUM process).
How big is the DB physically ("du $PGDATA" results)? If you've been lax
about vacuuming or not had your FSM parameters set high enough, there
could be a whole lot of dead space for VACUUM to scan through. If so,
VACUUM FULL or possibly CLUSTER would be the best way to re-compact the
tables. (VACUUM VERBOSE on your larger tables would be another way to
investigate this.)
The other possibility is that you have a seriously slow disk drive :-(
regards, tom lane