基于事务截止期的动态多粒度封锁机制

多粒度封锁机制提高了数据库系统的并发性，但在实时数据库中，由于事务处理的限时特性，对传统的多粒度封锁机制提出了挑战。综合考虑多粒度封锁机制与事务的截止期，提出了一种基于事务截止期的动态多粒度封锁机制，由事务截止期确定事务冲突级别，当事务冲突到达或降到一定级别后，根据当前加锁粒度决定是否对其进行调整。通过仿真实验证明本机制可减少事务冲突，降低事务错失率及事务重启率，提高了事务并发性和实时性。

Dynamic multi-granularity locking mechanism based on transaction deadline

Multi-granularity locking mechanism improves the concurrency of the database system. But in real-time database, the traditional multi-granularity locking mechanism meets serious challenge for the real-time demand of its transaction processing. In this paper, considering multi-granularity locking mechanism and the transaction deadline, a dynamic multi-granularity locking mechanism based on transaction deadline is proposed. The transaction conflicts level are determined by transaction deadline, and when the conflicts reach or drop to a certain level, the locking granularity is adjusted accortding to current locking granularity. Through simulations, the expermental results show that this mechanism can not only reduce transaction confilicts, but also reduce the miss ratio and restart ratio of transaction, improve transaction concurrency and real-time.