Research On Mobile Transaction Model Based On Multi-version Concurrency Control

The development and combination of computer technology and wireless communication technology made a new mobile computing mode appear. Mobile computing is the result of the combination of wireless communication, network and mobile computing device and a kind of more flexible and complex distributed computing environment. It has the characters of mobility, frequent disconnection, diversity of network condition, low bandwidth, limited electrical power capacity, asymmetry of network communication and high elasticity. Just because of the above characters, the traditional database technology cannot support mobile computing effectively. Therefore, it is necessary to study new database technologies and strategies.Mobile transaction processing technology is the key technology and a main research trend of mobile database. In the process of study, all kinds of mobile transaction processing models have been proposed. However, every model of them has a certain shortage, and they lack common standard, therefore, the further study is needed.On the basis of analyzing the characteristics of mobile computing environment and the shortages of existing mobile transaction processing models, this paper proposed a mobile transaction processing model, and studied the mobile transaction processing procedure, concurrency control strategy deeply. To improve the performance, this paper uses a multi-version transaction processing approach and a deadlock-free concurrency control mechanism based on multi-version two-phase locking scheme integrated with a timestamp approach. The concurrency control mechaniam aims to achieve high throughput rate and low abort rate by increasing data availability during concurrent read-write and write-write operations by reducing the revocation rate. In addition, the recovery mechanism used in the mobile transcation model is discussed.To test the performance of this model, this paper designed a simple mobile transaction prototype system, and the implementation method of mobile client machine and the mobile transaction manager was given. The performances of the model and O2PL model are compared using the simple model. The superiority of the model to O2PL model is proved by comparing the two parameters of throughput and abort rate.