Ken Corey <ken(dot)corey(at)atomic-interactive(dot)com> writes:
> Several of my tables are being emptied and totally replaced (statistics about
> how my website is running, that sort of thing). Is it better to drop the
> table, and rebuild it in this case?
Consider TRUNCATE.
I suspect if you look at the stats (see pg_class.relpages) you'll find
that the space VACUUM fails to reclaim is in indexes. Possibly you've
gone overboard on adding indexes to your database; are there any that
you don't need?
regards, tom lane