Real-time Optimistic Concurrency Control based on Transaction Finish Degree

Concurrency control is one of the main issues in the studies of real-time database systems. Optimistic concurrency control algorithms have the attractive properties of being non-blocking and deadlock-free. However, 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 in real-time database systems, they are still some unnecessary transaction restarts. In this study, we propose a new method called Transaction Finish Degree (TFD) and a new Multiversion Optimistic Concurrency Control algorithm based on TFD (MVOCC-TFD), which can reduce the number of unnecessary restarts. Theoretical analysis and experimental results demonstrate that the new algorithm can outperform the previous ones.