Support select distinct with multiple columns

[kiru]

SQLite does support selects with multiple joins, but with ecto I get an exception:

An exception is thrown at this place: https://github.com/elixir-sqlite/sqlite_ecto2/blob/7ba0b627108b0e1eb73d46741210bd7a11d4fd8b/lib/sqlite_ecto/connection.ex#L242

Is this just a not-implemented case?

What is the return value of the distinct method? (I am not that familiar with the codebase)

edit: It seems some select statement with distinct works. Can anyone explain this case?

https://github.com/elixir-sqlite/sqlite_ecto2/blob/master/test/sqlite_ecto_test.exs#L203