discourse/db/migrate/20191030112559_add_index_to_notifications.rb

# frozen_string_literal: true

class AddIndexToNotifications < ActiveRecord::Migration[6.0]
  disable_ddl_transaction!

  def up
    if !index_exists?(:notifications, %i[topic_id post_number])
      add_index :notifications, %i[topic_id post_number], algorithm: :concurrently
    end
  end

  def down
    raise ActiveRecord::IrreversibleMigration
  end
end