[erdemozg]

But it seems like this discussion is about the lack of support for null values in enum types in joins (not joins in general). Am I missing something?

[Foobar8568]

I got it wrong because of lack of documentations and examples in the official documentation. So one would be only aware of the feature if they read the issue tracker which is dumb, joining two entities (or more) is like the first thing you want to do with a database.