Priority assignment in distributed real-time databases using optimistic concurrency control

In the studies of distributed real-time database systems (DRTDBS), it is always assumed that earliest deadline first (EDF) is employed as the CPU scheduling algorithm. However, using purely (ultimate) deadline for priority assignment may not be suitable because different kinds of transactions, such as global and local transactions, may exist in the system. To improve the performance, more sophisticated priority assignment heuristics have to be employed. In the paper, the performance of different priority assignment heuristics for subtransactions in DRTDBS using optimistic concurrency control (OCC) protocol are investigated. It is found that purely deadline-driven heuristics, which suffice for distributed real-time systems, are not suitable for DRTDBS. On the other hand, the proposed heuristic, which considers both deadline constraint and data contention, can give the best performance. © IEE, 1997.link_to_subscribed_fulltex