discourse/db/migrate/20160215075528_add_unread_pm_index_to_notifications.rb

# frozen_string_literal: true

class AddUnreadPmIndexToNotifications < ActiveRecord::Migration[4.2]
  def change
    # create index idxtmp on notifications(user_id, id) where notification_type = 6 AND NOT read
    add_index :notifications,
              %i[user_id id],
              unique: true,
              where: "notification_type = 6 AND NOT read"
  end
end