Find rows with multiple duplicate fields with Active Record, Rails & Postgres

Question

What is the best way to find records with duplicate values across multiple columns using Postgres, and Activerecord?

I found this solution here:

User.f

Answer 1

If you need the full models, try the following (based on @newUserNameHere's answer).

User.where(email: User.select(:email).group(:email).having("count(*) > 1").select(:email))

This will return the rows where the email address of the row is not unique.

I'm not aware of a way to do this over multiple attributes.