Andrew Hodgson writes:
Are there any performance benchmarks for running MySQL vs PostGreSQL?
I think the Mailman devs like PostgreSQL because it tries harder to be a theoretically-correct RDBMS and because there was a mild stink of closed source around MySQL at one point. I recently saw a claim that PostgreSQL is now more performant than MySQL on some standard SQL benchmarks, but I don't have a cite so take that as a weak statement. (May have been a Xeet from the PostgreSQL devs. ;-)
I don't think there's a big difference either way. AFAIK there are only a few subqueries and joins in the normal Mailman workload and they're all reasonably optimized by both RDBMSes. I've not heard anybody complain of the DB performance as such.
Its worth noting this is more difficult to do now on Debian/Ubuntu installs as Python2 has been removed. This was something I ran into myself when trying to co-exist both installs on the same box.
Mark has Python 3 versions of the archive cleaning tools in his contrib directory. We didn't need a Python 2 installation, we just rsync'ed the mboxes across.
I do recommend using a tool to break large archives into smaller mboxes (our case was monthly anyway, but there were a few 10GB+ months in there that took many hours), and keep good logs. We had a "pulled the wrong plug" incident and recovering the archives from that was painful even though we had a pretty good idea of what was done and what wasn't. Ended up deleting a couple of posts from the HyperKitty archive and deleting half the posts in the list/month mbox in question and everything worked, but it was scary and being sure of everything we had and didn't have was tedious.
Steve