[GMG-Devel] Deprecating sqlite

[Christopher Allan Webber]

Hello!

So, I've begun looking and planning at my jumping back into MediaGoblin
development, and one thing that's been on my TODO list is raising
deprecating sqlite and going postgres-only.  This is something that
Jessica Tallon and I talked about quite a bit, and I said I'd send an
email, but oops.

There are two main reasons to do it:

 - sqlite is *the worst* when it comes to migrations.
   For more info:
     https://dustycloud.org/blog/sqlite-alter-pain/
   Probably more time has been sunk into fixing broken sqlite migrations
   than anything else in MediaGoblin's development.
   It's a huge timesink and painpoint.  Nobody likes working on these.

 - There are some big features we could really take advantage of if we
   went postgres-only.  Number one being jsonb support probably.
   This could end up improving our ability to adopt ActivityPub
   considerably (it's not a blocker on it maybe, but it could mean a
   dramatically cleaner implementation).

As to why not to do it:

 - Some people are already using it.  We could add scripts to help them
   move away though... we already did this once before with MongoDB ->
   SQL.
 - It's easy to administer as a *user* (even if it's the very opposite
   for developers).
 - It's easy to set up and uses very few resources.
 - It especially makes unit tests and etc very easy to do.

The last one is probably the most compelling of all of them to me
personally.  We need a decent way to start up / tear down databases for
testing.  (It may be possible to write some scripts that can start up /
tear down a temporary postgres cluster though...)  It's possible that we
could keep sqlite for a "development mode only", at least in some
interim, though it means still not having access to postres-only
features.  My feeling is, we should probably do this first.  If we do
that, we don't have to write migrations for sqlite anymore, at least.

Anyway, feedback welcome.  Personally, I think it would be a good move
towards this.

But, it's a pretty big change, so here's opening up conversation...