Remove duplicate records based on multiple columns?

Question

I\'m using Heroku to host my Ruby on Rails application and for one reason or another, I may have some duplicate rows.

Is there a way to delete duplicate records base

Answer 1

Based on @aditya-sanghi's answer, with a more efficient way to find duplicates using SQL.

Add this to your ApplicationRecord to be able to deduplicate any model:

class ApplicationRecord < ActiveRecord::Base
  # …

  def self.destroy_duplicates_by(*columns)
    groups = select(columns).group(columns).having(Arel.star.count.gt(1))
    groups.each do |duplicates|
      records = where(duplicates.attributes.symbolize_keys.slice(*columns))
      records.offset(1).destroy_all
    end
  end
end

You can then call destroy_duplicates_by to destroy all records (except the first) that have the same values for the given columns. For example:

Model.destroy_duplicates_by(:name, :year, :trim, :make_id)