Preliminary Research On Embedded Mobile Database

The development and integration of computer technology and wirelesscommunication technology have realized a brand new computing environment——mobile computing. Many concepts on mobile databases have been proposed.The study of mobile database has become a hot spot. This paper preliminaryresearch on embedded mobile database, and emphatically solve determining skewfactor which is the value of Zipf-MDSA, and using mutex in synchronousprocesses. The theta in Zipf function is skew factor. The greater the theta is,its distribution is more gradient. The access-probabilityθis depended onthe request of actual mobile customer, and disk skew factor doesn't have theunique value. Different value of theta has great impact on the result ofdisseminating plate as well as the mean Access Time. The response speed ofthe mobile users is also depended on the Access Time, which is going to affectthe database performance. The mutex is synchronous object of windowssystem. Using mutex in synchronous processes can simplify the synchronousprocesses and reduce the spending of system.Data broadcasting is an important way for data dissemination in mobileenvironment. It can efficiently support access to hot data with commoninterest. One of the principal problems of data broadcast is how to schedulethe broadcast data, so as to optimize the Access Time and Tuning Time of thebroadcast. A lot of broadcast tuning research and methods have been paid onreducing the accessing time. The paper illustrates advantages of multi-diskschedule by comparing the uniform schedule with non-uniform of data broadcast.It has analyzed the formula of mean minimum Access Time in invariable lengthitems, and the realization condition.Then the paper introduces a multi-disk broadcast scheduling algorithmbase on Zipf rule. Though proposed the distributed plate strategy based on Zipf-MDSA had been mentioned in many documents, people didn't discusse thevalue of skew factor further. Also the influence on the result of distributingplate is quite large. Therefore the proposed method of determinating thetais quite significant. Later it discusses how to determinate the value ofaccess-probability and disk skew factor based Zipf-MDSA. Finally the paperssimulates the realization by c language and calculated the average minmumAccess Time.There is more detailed study and analysis of the mobile databasesynchronized mechanism for all key technical issues, focusing on the analysisof data distribution, data consistency, recovery, and so on. Finally itproposes using mutex in the synchronous process. Mutex is a data structure,which can guarantee that it can be used at anytime by the identical user whichmay be the process, thread or other any main body. Finally the paperintroduces how to design program of read-write control and read-writesynchronization demonstration, flow charts of two programs.