Over the last decade, large amounts of concurrent transactions have been generated from different sources, such as, Internet-based systems, mobile applications, smart-homes and cars. High-throughput transaction processing is becoming commonplace, however there is no testing technique for validating non functional aspects of DBMS under transaction flooding workloads. In this paper we propose a database state machine to represent the states of DBMS when processing concurrent transactions. The state transitions are forced by increasing concurrency of the testing workload. Preliminary results show the effectiveness of our approach to drive the system among different performance states and to find related defects.