Re: Vacuum writes on empty system

"onion" <onion@taxi.com> writes:
> I just loaded up 9GB of data (32 tables) into a brand new system (Postgres
> 7.4.5 on Linux 2.4 with 1GB ram, IDE). I immediately ran "vacuum analyze"
> but Postgres seems to be writing a lot to disk even though none of the
> tables have incurred any UPDATES or DELETES yet and there are no other
> connections or process running. Is it normal for vacuum to be writing to
> disk even when there is nothing to clean up?

Your assumption that there is nothing for VACUUM to do is mistaken.

It's probably setting the known-committed hint bits in all the tuple
headers of the newly loaded data.
        regards, tom lane