Dynamic adjustment of execution order in real-time databases

Summary form only given. Many researches have been devoted to designing appropriate concurrency control algorithms for real-time database systems, which not only satisfy consistency requirements but also meet transaction timing constraints as much as possible. Optimistic concurrency control protocols have the nice properties of being nonblocking and deadlock-free, but they have the problems of late conflict detection and transaction restarts. Although the number of transaction restarts is reduced by dynamic adjustment of serialization order (DASO) in real-time database systems, it still has some unnecessary transaction restarts. We first propose a new method called dynamic adjustment of execution order (DAEO) and a new optimistic concurrency control algorithm based on DAEO, which can reduce the number of unnecessary restarts near to zero and outperforms the previous algorithms, and then discuss the experiments and the results.