Abstract. We present a general and effective method to certify completeness of query results on relational tables stored in an untrusted DBMS. Our main contribution is the concept of "Query Race": we split up a general query into several single attribute queries, and exploit concurrency and speed to bind the complexity to the fastest of them. Our method supports selection queries with general composition of conjunctive and disjunctive order-based conditions on different attributes at the same time. To achieve our results, we require neither previous knowledge of queries nor specific support by the DBMS.We validate our approach with experimental results performed on a prototypical implementation.