Key Technologies On The Concurrency Control Chanism Of Database Transaction In Grid

Concurrency control mechanism is an important part of transaction managements in distributed database system, and it is one of the important symbols to measure the capability and function of DBS (Database System), The emergence of grid technology enable the sharing of the geographically distributed and heterogeneous resources. Grid database is a combination of database technology and grid technology, and it is a new research, having brought new changes in the traditional sense of the database. Because the grid is heterogeneous, distributed, autonomous and dynamic, the traditional methods of concurrency control have not been suited to the grid. Therefore, it is a concurrent imminent for Grid-controlled study.The main content is as follows: this thesis analyzed the characteristics of the transaction under the grid environment , puts forward the transaction model which suits for grid environment-transaction model based on agent for grid. That model makes use of the technique of agent and grid-middleware , which adapt the long term, dynamic characteristic request of transaction in grid environment support the participant's autonomy and cooperation, support the resources' heterogeneity of grid environment at the same time. Model access the database with quomodo based on service, embody the characteristics of grid fully. Grid middleware services provide communication and cooperation among stations. analyzing concurrency control methods of the distributed database in detail, a correctness criterion for grid database is given; Two concurrency control methods are proposed. The protocol which is based on timestamp in grid extends the transaction type: browse transaction, read-only transaction, update transaction and append transaction, so many conflicts are avoided. In extended declaration lock model based on 2PL, we extend the simple lock mode-shared lock/exclusive lock by introducing several other locks. It supports cooperative design in transaction management of grid database system. This thesis designs a simulation test project based on OGSA, consequently, we test the grid database transaction model and two methods of concurrency control. The results of the experiment in a prototype system show that the transaction model can effectually control the concurrency of users, and that two concurrency control methods are feasible and effective especially when the read-only transaction and browse transaction have larger scale than others. The significance of the thesis is that it develops research on the transaction model of grid database service management and concurrency control mechanism based on elaborating current service management and concurrency control mechanism, which improves the collaborative ability of product development and does good to the efficiency of usage and meets the need of mass-dealing of database with low cost. Furthermore, the thesis plays an important role in broadening the transaction model of grid database service management and concurrency control mechanism, bettering the implementation of database technology in designing area, exploring usage of grid in industrial design.