Postgres 7.4 and vacuum_cost_delay.

Hi everyone.

I've got a quick and stupid question: Does Postgres 7.4 (7.x) support
vacuum_cost_delay?

For all my googles and documentation reading I've determined it's not
supported, only because I can't find a 7.x doc or forum post claiming
otherwise.

Upgrading to 8.x is out of the question, but I still need to employ
something to auto-vacuum a large and active database (possibly more than
once a day) in a manner that wouldn't affect load at the wrong time.

If I could combine pg_autovacuum with vacuum_cost_delay I could potentially
have a solution. (barring some performance testing)

The only problem with pg_autovacuum is the need for pg_statio, which itself
will reduce performance at all times.

Any suggestions?

Thanks!

- Chris