INTEGRATING STANDARD TRANSACTIONS IN FIRM REAL-TIME DATABASE-SYSTEMS

Real-time database systems are designed to handle workloads where tran sactions have completion deadlines and the goal is to meet these deadl ines. However, many real-time database environments are characterized by workloads that are a mix of real-time and standard (non-real-time) transactions. Unfortunately, the system policies used to meet the perf ormance goals of real-time transactions often work poorly for standard transactions. In particular, optimistic concurrency control algorithm s are recommended for real-time transactions, whereas locking-based pr otocols are suited for standard transactions. In this paper, we presen t a new database system architecture in which realtime transactions us e optimistic concurrency control and, simultaneously, standard transac tions use locking. We prove that our architecture maintains data integ rity and show, through a simulation study, that it provides significan tly improved performance for the standard transactions without diminis hing the real-time transaction performance. We also show, more general ly, that the proposed architecture correctly supports the co-existence of any group of concurrency control algorithms that adhere to a stand ard interface.