移动环境下实时事务处理

1 引言实时数据库就是其中的事务和数据都可能有时间限制的数据库。近些年来,越来越多的研究人员对于移动实时数据库系统(Mobile Real-Time Database System:MRTDBS)中高效的事务处理方法进行了研究,一般认为移动实时数据库就是移动环境(如GSM网络和无线局域网)所支持的实时数据库系统。对于实时事务来说,其完成时间一般有相应的时间约束,满足事务截止时间约束往往比事务逻辑完全正确更重要,例如对于股票查询的延迟响应会导致失去很好的交易机会。为了满足事务的截止时间约束,人们提出了不同的事务调度技术和并发控制协议。

Real-time Transaction Processing in a Mobile Environment

With the advances in mobile computing technology .there is an increasing demand for processing real-time transactions in a mobile environment. This paper proposes a multi-version data model. Based on this data model, we present a relative timing correctness criterion for real-time transactions in a mobile environment. As long as the data staleness is in a controlled extent, it is unnecessary for all the accessed data are valid when a real-time transaction commits. Also this paper gives a transaction execution model based on the image transaction concept. All these strategies not only decreas the cost for the transaction concurrency control,but also increase the possibility to meet mobile real-time transactions'deadlines by sacrificing the relatively transaction timing correctness. This is in accordance with the real-time transaction property that a relatively correct and in-time result is more preferable than an absolutely correct but obsolete result.