"vacuuming..." in nightly report

[Brian Behlendorf]

In my nightly status report, towards the end, I see the word 
"vacuuming...", by itself, with no context.  I don't see mention of it in 
anything under /etc or /usr/src, except games/fortune or share/dict. 
Google suggests this is something Postgres does, and while Postgres is 
installed and running it's not in production use, nor does anything 
related to PG appear to be called by the periodic scripts.  Very strange. 
Daily scan included below, with sensitive data elided with a [...]. 
Thoughts?

 	Brian

---------- Forwarded message ----------
Date: 1 Mar 2005 11:19:27 -0000
From: root at hyperreal.org
To: root at hyperreal.org
Subject: taz3.hyperreal.org daily run output

Removing stale files from /var/preserve:

Cleaning out old system announcements:

Removing stale files from /var/rwho:

Backup passwd and group files:

Verifying group file syntax:

Backing up mail aliases:

Rotating accounting logs and gathering statistics:

Disk status:
[...]

Last dump(s) done (Dump '>' file systems):

UUCP status:

Network interface status:
Name    Mtu Network       Address              Ipkts Ierrs    Opkts Oerrs  Coll
[...]

Local system status:
  3:01AM  up 354 days,  6:19, 16 users, load averages: 0.76, 0.69, 0.72

Mail in local queue:
messages in queue: 868
messages in queue but not yet preprocessed: 0

Security check:
     (output mailed separately)

Checking for rejected mail hosts:

Checking for denied zone transfers (AXFR and IXFR):
    1 apache.org from 194.159.246.198 (no-dns-yet.demon.co.uk)

vacuuming...

-- End of daily output --