Derek Chen-Becker <dbecker@cpicorp.com> writes:
> I'm running OpenNMS on a machine that was misconfigured and our
> event database climbed to 2.8 million rows. I've gone in and archived
> that vast majority out to files on disk and now the table has about
> 20-30k rows. When I do a "vacuum full", though, it says that the vast
> majority of the rows are dead rows that are unremovable.
> Do I have a corrupted DB?
More likely you have an ancient prepared transaction that was never
committed. Look in pg_prepared_xacts.
regards, tom lane