In addition, I believe Matt Simerson authored a tcpserver mysql patch to allow the removal of cdb files altogether. http://www.tnpi.biz - it's great for heavily loaded servers, because constantly recompiling that damn file with multiple processes tends to corrupt it.
Eh? Rebuilding it while multiple processes are accessing it corrupts it?!? Or multiple processes trying to rebuild the same file?
I love qmail too, but I'm with ya on all the 'unapproved' patches and it's concurrency limitations.
The mysql side of things could be alleviated by using sqlrelay. Don't hammer mysql. Hammer sqlrelay instead :)
Christopher