why is autovacuum still ongoing even if set to off ?

Hi,

I'm running 8.4 and I've tried to disable autovacuum since the vacuuming is
taken care internally in the code. The same was true with the previous
version (8.0 to 8.3) and there was never any problem. However now in 8.4 the
"off" setting seems to be ignored even if "track_counts = off" and huge
naptime and thresholds are set. For example this is in the logs:

2009-07-30 22:40:25 CEST - : LOG: automatic vacuum of table "t.x": index
scans: 0
pages: 0 removed, 43035 remain
tuples: 0 removed, 6459092 remain
system usage: CPU 0.73s/0.80u sec elapsed 112.01 sec
2009-07-30 22:43:05 CEST - : LOG: automatic vacuum of table "t.y": index
scans: 1
pages: 0 removed, 47527 remain
tuples: 867656 removed, 6588630 remain
system usage: CPU 1.07s/4.12u sec elapsed 159.99 sec

Since there are a lot of tables like this (160GB in total) and the insert
time is critical we cannot afford having autovacuum messing up the ongoing
activity. Is there a way to completely switch it off ?

Btw, the database is one week old, vacuum procedures run anyway often enough
(but with large intervals between them so normal operations have a chance to
catch up), so there is really no need to have autovacuum doing maintenance
operations.

Thanks a lot in advance!

.costin