移动广播环境中的可串行化并发控制协议

研究了非对称通信数据广播环境中的一致性问题．PVTO协议中数据冲突的检测过于严格，存在很多不必要的事务夭折，限制了其并发度；O—PreH协议中数据冲突的检测过于宽松，必要的事务重启要等待服务器校验，浪费了大量昂贵的上行通信带宽．提出了一种新的可串行化并发控制协议BCC—SR．BCC—SR协议将时标段排序和乐观方法相结合，使用了恰当的校验条件，既避免了不必要的事务夭折，又可尽早处理必要的事务重启，节省了系统资源，提高了并发度．实验结果表明，BCC—SR协议能有效改进移动事务的平均响应时间，更好地满足数据广播环境中高性能事务处理的要求．

A Serializable Concurrency Control Protocol in Wireless Broadcast Enviroments

The issue of data consistency in mobile broadcast environments characterized by its asymmetric communication capacity is studied. For the protocol O-PreH, many necessary aborts need waiting for the validation on server, and therefore a lot of expensive upstream communication capacity is wasted. For the protocol PVTO, the validation condition is too strict, and thus many unnecessary aborts are induced and the degree of concurrency is restricted. In this paper, a new serializable concurrency control protocol BCC- SR is proposed. Compared with PVTO and O-PreH, the protocol BCC-SR performs better pre-validation processes on mobile hosts and their server, resulting in both less wasted resources and a smaller number of aborts. The simulation results confirm that the proposed protocol could improve the average response time of mobile transactions significantly.