This is exactly what happens in a typical Elixir project even though Ecto is a query builder and not an ORM. People define their domain entities as database tab

This is exactly what happens in a typical Elixir project even though Ecto is a query builder and not an ORM. People define their domain entities as database tables. The result is, from my latest project, you have user and organisation memberships which are a list of membership records. This is carried throughout the application while it should be a hash map of organisation IDs and membership data, so you can check if a user is a member of an organisation in constant time. Of course keeping ourselves coupled to the database representation is easier than defining a view, for example, which takes care of presenting the data in a useful form for the application.