Distinct with 2 keys or more

[abdelhalim97]

Elixir version

1.18.3

Database and Version

MySql 8.0.35

Ecto Versions

ecto 3.12.5

Database Adapter and Versions (postgrex, myxql, etc)

ecto_sql 3.12

Current behavior

schema "logs" do
    field :action, :string
    field :user_id, :integer
    field :smth, :string
  end

from(l in Logs,
  distinct: [l.action, l.user_id]
)
|> Repo.all()

It returns a misleading error that confused me it says:

DISTINCT with multiple columns is not supported by MySQL in query:

from p0 in Ovice.Model.Log,
  distinct: [asc: p0.action, asc: p0.user_id],
  select: p0

I really thought that ecto doesnt support DISTINCT with more than single column when mysql does

Expected behavior

Expected that this query will do distinct on both fields like this examle that works fine and as expected:

 from(l in Logs,
select: [l.action, l.user_id],
      distinct: true
    )
    |> Repo.all()

Unless i misunderstood something, both queries should have same output.
If yes i d like to work on it myself please 🙏

[josevalim]

Thank you! Yes, we can clarify to say: to apply distinct to multiple columns at once, use distinct: true. A pull request is welcome. It should be sent to the https://github.com/elixir-ecto/ecto_sql repository.

[abdelhalim97]

Ok thank you i ll start working on it soon

[josevalim]

Closing in favor of the PR!