text: -- +migrate Up
  
  ALTER TABLE heartbeat_monitors
      DROP CONSTRAINT heartbeat_monitors_service_id_fkey,
      ADD CONSTRAINT heartbeat_monitors_service_id_fkey FOREIGN KEY (service_id) REFERENCES services (id) ON DELETE CASCADE;
  
  -- +migrate Down
  ALTER TABLE heartbeat_monitors
      DROP CONSTRAINT heartbeat_monitors_service_id_fkey,
      ADD CONSTRAINT heartbeat_monitors_service_id_fkey FOREIGN KEY (service_id) REFERENCES services (id);
  