Problems with autovacuum and vacuum

Hello,

Last week I had a serious problem with my PostgreSQL database. My autovacuum
is OFF, but in September it started to prevent the transaction wraparoud;
however last week the following message appeared continuously in my log:

WARNING: database "production" must be vacuumed within 4827083 transactions
HINT: To avoid a database shutdown, execute a full-database VACUUM in
"production".

This message appeared for five to six hours; after that, the message
disappeared from log. Any idea about what could have happened?

Every day the vacuum is executed on some tables; and on Sundays it's
executed on all tables. But as the autovacuum is running since September,
and it runs for a long time, the vacuum was blocked because autovacuum had
been running on the same table. How should I procede in this case?

The table where the autovacuum is running and where the vacuum was blocked
has billion of rows.

I'm using the PostgreSQL 8.3.8

The configuration of the vacuum parameters are:

vacuum_cost_limit = 200
vacuum_cost_delay = 0
vacuum_freeze_min_age = 100000000
autovacuum = off
autovacuum_freeze_max_age = 200000000

Regards,

João Paulo

--
JotaComm
http://jotacomm.wordpress.com