auto vacuum

Hi All -

We run both postgres 8.2.3 and 8.4.1 in unix environment. We have auto
vacuum configured and I am trying to find out its effectiveness. Here
are a couple of questions:

1) I'm running a query that compares actual table count with the pg_stat
table count ( pg_stat_user_tables.n_live_tup) to make sure there is not
a huge difference between two. If the difference is small or within the
analyze threshold I know vacuum analyze is running and doing its work. I
am seeing that truncate does not trigger autovacuum analayze like delete
does and pg_stat_user_tables.n_live_tup is not updated ( please correct
me If I am wrong). Does it mean I have to run analyze manually whenever
I truncate a table or system has a way of tracking.

2) In postgres 8.2 pg_stat_user_tables.n_live_tup field is missing. Is
there a way to get table counts as the system sees it in 8.2?

Thanks.

Dinesh