基于级联深度的主动实时乐观并发控制协议

主动实时数据库因结合了时间限制与主动机制而使系统事务的并发控制变得更为复杂。主动规则的引入使事务触发新的事务且在执行上具有多种耦合方式,传统的实时并发控制策略无法对具有复杂执行模式的事务进行有效调度,而基于主动数据库的并发控制机制也没有考虑事务的实时性问题。通过对事务不同耦合方式的实时要求及事务间冲突关系进行分析,提出了新的主动实时数据库乐观并发控制方法,对不同事务级联深度进行评估,结合事务执行的时间信息对冲突事务进行动态调整串行化顺序。理论分析与实验证明,能在保证事务可串行性的同时降低了不必要事务重启个数,更好地满足系统的实时性。

Active real-time optimistic concurrency control based on cascade depth

In active real-time database systems,transaction concurrency control gets more difficult for integrating time constraint with active mechanism.There are many coupling execution model between triggering transaction and triggered transaction.The conventional real-time concurrency control method can not schedule availably the transaction having complexity execution model,and the active concurrency control method can not resolve the problem of transaction timeliness.A new active real-time optimistic concurrency control protocol is proposed after analyzing the couple model timeliness request and the relation among conflict transactions,which evaluates the transactions cascade depth and adjusts dynamically the commit order of conflict transactions.Theoretical analysis and experimental results demonstrate that the new method can outperform the previous ones.