MySQL index hint support for ActiveRecord
Add this line to your application's Gemfile:
gem 'activerecord-mysql-index-hint'
class Product < ActiveRecord::Base
end
Product.where(user_id: 1).force_index(:idx_user_id).first
# => SELECT `products`.* FROM `products` FORCE INDEX(`idx_user_id`) WHERE `products`.`user_id` = 1 LIMIT 1