Vacuuming Questions

We have two PostgreSQL servers (8.2) running in a cluster.

We have autovacuum switched on on both servers and also we are running
the following as a cron job;

Server 1:
30 0,2,4,6,8,10,12,14,16,18,20,22 * * * /usr/bin/vacuumdb --all --analyze

Server 2:
30 1,3,5,7,9,11,13,15,17,19,21,23 * * * /usr/bin/vacuumdb --all --analyze

So, in other words we stagger the jobs one each server in the cluster.

Now, we're not seeing any problems with performance and we're not seeing
any bloat but I have a couple of questions which I hope some of you can
help me out on.

1) Is using the autovacuum daemon and running vacuumdb from a cron job
overkill?

2)  The vendor of the clustering software suggests that I regularly run
vacuum --all --analyze on a specific table.  Surely, if I'm running
vacuumdb --all --analyze isn't this just a wrapper for running the
vacuum --all --analyze command anyway?  I guess that I'm asking why
would I want to run vacuum --all --analyze on a specific table, when I
regularly run vacuumdb --all --analyze on all databases?

Any help would be grateful.

Thanks

John