[Exim] Persistent DB connections to MySQL database

This is a multi-part message in MIME format.
--
[ Picked text/plain from multipart/alternative ]
First let me say that Exim is the greatest MTA ever created and I sing its praises every chance I get. I can't imagine trying to get any other MTA to do the insane but completely useful convolutions we put Exim through every day.

That said, I'd like to make a feature request, without the slightest idea of how difficult it would be to implement:
Persistent DB connections, just like Apache::DBI in mod_perl

This was mentioned on the list about 3 years ago without any further conversation.

We make very heavy use of MySQL in our mail setup (and I don't see how it could be feasible to do large-scale mail operations without connecting to a DB or LDAP backend). The result is that we have upwards of 20-30 MySQL connections open at any time. Our DB can handle the load pretty well, but if the DB connections were persistent, I imagine that we could squeeze out some pretty nice extra performance. Just seems like a lot of overhead to create and tear down so many TCP sessions. Having a pool of DB connections cached to be reused would be much more efficient.

Just a thought.

And heck, while I'm day-dreaming, any chance of being able to tune the size of the cache? We've got plenty of memory left over running only exim. I'd love to be able to bump the lookup cache well above just the last lookup. The memory consumption of having, say, the last 20 lookups cached per type would be trivial compared to the gains in the reduction of overhead.

Again just a thought :) A thousand pardons if I missed any subsequent conversation on either topic while searching the list archives.
--