I finally committed the new version of the FSM rewrite, after fixing the
latest round of Tom's comments. There's a few loose ends I'm going to
address as subsequent patches:
pg_relation_size() doesn't include the size of the FSM. Should it? I'm
thinking "no", but pg_total_relation_size() should.
The FSM is not updated during WAL replay. That means that after crash
recovery, the FSM won't be completely up-to-date, but at roughly the
state it was at last checkpoint. In a warm stand-by, the FSM will
reflect the situation at last full backup. We need to think when the FSM
should be updated during WAL replay. Probably not after every record,
because of the overhead, but certainly more often than never.
VACUUM VERBOSE output no longer prints the number of pages with "usable
free space", because we no longer track such a value during the vacuum.
You can use contrib/pg_freespacemap to view the contents of the FSM in
detail, but should VACUUM VERBOSE still print something about the amount
of free space on the relation? Perhaps the total amount of free space in
the relation?
-- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com