Conflict free transaction scheduling using serialization graph for real-time databases

A best effort approach to data scheduling, such as optimistic concurrency c ontrol in real-time database systems (RTDBS), imposes a heavy burden on the systems by restarting conflicting transactions. The restarted transactions themselves may miss their deadlines and the resources consumed by them may be wasted. Hence it can be better to schedule transactions such that only conflict free transactions can be executed concurrently at one time. This s tudy explores this approach by making use of serialization graph testing. A serialization graph is used to enforce the serializability of transactions . Only transactions without data conflicts with the executing transactions will be allocated CPU. Consequently, conflict free concurrency among execut ing transactions can be achieved. All resources including CPU, I/O and data objects will not be wasted on restarted transactions. Therefore, the syste m can sustain a higher workload. We also devise a real-time serialization g raph that considers the timing constraints of transactions. By using our pr otocols, only a limited amount of transaction delay overhead is observed. H owever, experimental results confirm that the overall performance of our pr otocols is better than the real-time optimistic concurrency control (OCC) p rotocol that is reported as one of the best performing data scheduling appr oaches in RTDBS. (C) 2000 Elsevier Science Inc. All rights reserved.