def mexists(self, bid_list):
        q = {
            "query": {
                "ids": {
                    "values": bid_list
                }
            }
        }
        res = self._es.search(index=self._index, doc_type=self._doc_type, body=q, stored_fields=None, size=len(bid_list))
        # id_set = set([doc['_id'] for doc in res['hits']['hits']])     # TODO: Confirm this line
        id_set = {doc['_id'] for doc in res['hits']['hits']}
        return [(bid, bid in id_set) for bid in bid_list]