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

That error occurs because POSTGRES requires you to put grouping columns in the SELECT clause.

try:

User.select(:first,:email).group(:first,:email).having("count(*) > 1").all

(note: not tested, you may need to tweak it)

EDITED to remove id column