How to monitor or do vacuum without stop all?
VACUUM FULL takes an ACCESS EXCLUSIVE lock on the table, then rewrites the whole table. This will take a long time for a large table, especially since it must also rebuild all indexes. You haven't said anything about the table size or the server's I/O subsystem so it's hard to say if 5 hours is unexpected or not.

You shouldn't generally need to use VACUUM FULL. Just use ordinary VACUUM - and turn autovacuum up so it works harder if you need to do a manual VACUUM more than very occasionally. It is safe to cancel the VACUUM FULL; doing so will undo all it's work, though.

You generally only need to run VACUUM FULL if you're trying to recover from severe table bloat caused by a long-running &lt;IDLE&gt; in transaction connection, an abaondoned prepared transaction, insufficiently aggressive autovacuum, etc. If you can't afford the downtime required for this you can look into pg_reorg as an online, reduced-locking alternative.