def _delete_ref(self, bch, obj_type, obj_uuid, ref_obj_type, ref_uuid):
    send = False
    symmetric_ref_updates = []
    if (bch is None):
        send = True
        bch = self._cassandra_driver.get_cf_batch(datastore_api.OBJ_UUID_CF_NAME)
    self._cassandra_driver.remove(obj_uuid, columns=[('ref:%s:%s' % (ref_obj_type, ref_uuid))], batch=bch)
    if (obj_type == ref_obj_type):
        self._cassandra_driver.remove(ref_uuid, columns=[('ref:%s:%s' % (obj_type, obj_uuid))], batch=bch)
        try:
            self.update_last_modified(bch, obj_type, ref_uuid)
            symmetric_ref_updates = [ref_uuid]
        except NoIdError as e:
            pass
    else:
        self._cassandra_driver.remove(ref_uuid, columns=[('backref:%s:%s' % (obj_type, obj_uuid))], batch=bch)
    if (ref_obj_type not in self._obj_cache_exclude_types):
        if (ref_obj_type == obj_type):
            self._obj_cache_mgr.evict(obj_type, [ref_uuid])
        else:
            self.update_latest_col_ts(bch, ref_uuid)
    if send:
        bch.send()
    return symmetric_ref_updates
def _delete_ref(self, bch, obj_type, obj_uuid, ref_obj_type, ref_uuid):
    send = False
    symmetric_ref_updates = []
    if (bch is None):
        send = True
        bch = self._cassandra_driver.get_cf_batch(datastore_api.OBJ_UUID_CF_NAME)
    self._cassandra_driver.remove(obj_uuid, columns=[('ref:%s:%s' % (ref_obj_type, ref_uuid))], batch=bch)
    if (obj_type == ref_obj_type):
        self._cassandra_driver.remove(ref_uuid, columns=[('ref:%s:%s' % (obj_type, obj_uuid))], batch=bch)
        try:
            self.update_last_modified(bch, obj_type, ref_uuid)
            symmetric_ref_updates = [ref_uuid]
        except NoIdError as e:
            pass
    else:
        self._cassandra_driver.remove(ref_uuid, columns=[('backref:%s:%s' % (obj_type, obj_uuid))], batch=bch)
    if (ref_obj_type not in self._obj_cache_exclude_types):
        if (ref_obj_type == obj_type):
            self._obj_cache_mgr.evict(obj_type, [ref_uuid])
        else:
            self.update_latest_col_ts(bch, ref_uuid)
    if send:
        bch.send()
    return symmetric_ref_updates