Support for mariadb?

[frank-emrich]

When releasing the links-mysql package, someone from the opam team pointed out that our links-mysql.opam file lists the following dependencies:

depends: [
  "ocaml" {>= "4.08.0"}
  "dune" {>= "1.10.0"}
  "conf-mysql"
  "mysql"
  "links"
]

However, depending on both mysql and conf-mysql is slightly redundant, as mysql already depends on ("conf-mariadb" | "conf-mysql"). Therefore, our dependency on conf-mysql essentially just means that we rule out mariadb. Is this on purpose or should we get rid of this restriction?

[jamescheney]

This is intended (for now).

We have not tested with mariadb as far as I know; we can remove this once we have done so and made any changes needed.

This is actually something we might do fairly soon, since mariadb supports some temporal database extensions that @SimonJF was planning to compare with his work.

[jamescheney]

Incidentally, our dependency doesn't rule out mariadb, it just means that links-mysql installation won't succeed unless conf-mysql is also installed. So it just has the effect of saying that while ocaml-mysql requires either mysql or mariadb, links-mysql really requires mysql at least at the moment. It doesn't stop someone from also having mariadb installed or even from trying to use Links with it, I just don;t want people to think this is a possibility when we haven't tried it ourselves.

[frank-emrich]

Good point. What I meant by "ruling out" mariadb was that our current configuration doesn't allow installing Links on a platform that provides conf-mariadb but not conf-mysql. But that's more of a theoretical aspect, it is not the case that the former is provided on more platforms/configurations than the latter. Since the update to conf-mysql a few days ago (potentially triggered by our Links release failing to build on many platforms), it is actually the other way around.