A real-time concurrency control algorithm: Use of multiversion and precedence relationships

This paper proposes a multiversion concurrency control algorithm for real-time databases. Based on a priority cognitive algorithm commonly used in real-time processing, the algorithm resolves data conflicts among conflicting transactions in favor of the urgent transactions, i.e., those with higher priority. Our algorithm is expected to minimize the transactions missing those deadlines and increase the degree of transaction concurrency by using precedence relationships and multiple versions. In the algorithm, a precedence relationship, which implies a serialization order among conflicting transactions, is utilized to resolve data conflicts. By exploiting precedence relationships, our algorithm can avoid deadlocks, and dynamically determine the abortion of lower priority transactions depending on the likelihood of roll-backs and the amount of the work done by the low priority transaction.