[linsomniac]

I've been running some small galera clusters for close to a decade with very good results. It's multi-master, and mostly "just works", though once every year or three I have to go in and re-bootstrap the cluster from the node with the highest sequence number if all of the nodes have gone down for one reason or another. I have some ansible playbooks and scripts that help with it.

My use case is a fairly small database of email address mappings. I have a mail server that sends out emails on behalf of our users, using their outside e-mail address (gmail, yahoo, whathaveyou). In order to allow replies, but prevent being an open relay, I have a milter that creates a lookalike address, with a token in it ([e-mail] -> [e-mail]).

I store those mappings in the mysql database, less than 10K of those. So a trivial database, very high read to write ratio.

More recently, maybe 3-4 years ago, I added another couple tables that store all the logs. I have a job that reads the postfix logfiles and writes out all the log information so we can show users the status of every of their outgoing e-mails. That upped the amount of traffic to the database by quite a lot, but it's still pretty simple: basically no transactions, just simple single insert statements, and IIRC one overview table that gets some updates, then a clean up job to delete them after 30-90 days.

Galera has been a real workhorse.

For a while I was going to go with cockroachdb, and I set up a POC. It was pretty robust with setting it up and clustering, I never ran into having to re-bootstrap the couster. But, at the time, postfix couldn't write directly to cockroachdb because cockroach could only do UTF-8, and the postfix pgsql code would only do latin-1 or something. This has changed since and I've thought about switching back to cockroach, but I hear there are some licensing issues I may have to be aware of.