Concurrency Control Of Embedded Mobile Real-time Database System

Database system is a perfect core technology that is adapted to the needs of data processing, its appearance is a milestone in computer application area which makes the main computer applications from scientific computing to data processing.With the increase need of real-time applications, as well as mobile communication technology and the rapid development of the large number of mobile computers, the database system that is combined mobile computing,real-time applications and the traditional database technology has became a focus in the research of database. The study of concurrency control mechanism in embedded mobile real-time database system (EMRTDBMS) has became the key technology.In EMRTDBMS, wireless network has the features of low bandwidth, asymmetry and poor quality,concurrency control is not only to meet the basic characteristics of traditional affairs, it also has to consider the problem of priority reversing, fruitless restarting and consistency of global data. WSR-HP2PL is an effective control strategy in EMRTDBMS.WSR-HP2PL use optimistic concurrency control as the basic idea which makes mobile transaction execute in the client first, and use HP-2PL to ensure the serialization of update transactions. In order to adapt to the characteristics of embedded mobile environment, it uses WSR to keep database consistency and increase the concurrency control of mobile transaction which allows read-only transactions read some dirty data.Based on WSR-HP2PL , we implement a prototype system for measuring the performance of provided scheduling strategy. Simulated experiment shows that WSR-HP2PL is better than some other strategies on miss rate, count of restarting .