I wish they would be so keen on migrating to MySQL 8.0 as well :-)
Their (amazing) tool Gh-ost is broken on MySQL 8.0, which suggests that they're still based on 5.7.
It's a big issue for my company (and I guess for any mid-sized company), since at mid-sized companies the schema is likely big enough to have slow migrations, but not big enough to have fancy replication topologies. For such cases, there's nothing like Gh-ost :-)
So far I haven't seen many people switching to MySQL 8... almost every example and app I've seen in the wild is on 5.6 or 5.7, or switched to MariaDB (or more infrequently, Postgres).
Well, if we put it this way, the same could be said of Rails 6. I understand their plans of course, and that's why I expressed it as wish.
Regarding MariaDB or PostgreSQL, can you enumerate/detail the app you've seen switching? Is it the, say, 1/2% area of all the projects? 5%?
Probably, in the low one-digit percentage, there are switches toward anything. I'm somewhat skeptical any non-trivial projects undertaking this kind of change. GitLab (to mention a large one) didn't really switch, as they were supporting both.
When you install 'mysql'/'mysqld' in Debian or RHEL7+-based distros, you get MariaDB... So staying with MySQL and not "switching" to MariaDB is a lot more effort. (MariaDB is a fork of MySQL and the binaries and everything even have mysql in the name so everything just works. I'd assume there might be some divergence in newer features, but I haven't noticed anything in that regard.)
Their (amazing) tool Gh-ost is broken on MySQL 8.0, which suggests that they're still based on 5.7.
It's a big issue for my company (and I guess for any mid-sized company), since at mid-sized companies the schema is likely big enough to have slow migrations, but not big enough to have fancy replication topologies. For such cases, there's nothing like Gh-ost :-)