[Exim] MySQL persistant?

Hi,

We are running Exim 4.30, and are considering using MySQL lookups
in our Exim config in various spots.

However, we run a fairly high volume mail server and I am concerned
that MySQL database connections will have to be rebuilt for each new
incoming message.

Does Exim set up the MySQL connection in the parent listener process
(-bd switch), and then pass on the open connection to all of its
forked children, or does a new connection have to be built for
each child that needs to do a query?

Performance is really the issue here, and am concerned about
the overhead on our MySQL server of dealing with thousands of
new connections per minute.

Thanks...

--
Dean Brooks
dean@???