Global Grant Design And Realization In Distributed And Parallel Database System

It is harder and more complicated in distributed database system, especially in distributed and parallel database system (DPDBS), than in centralized database system for the complexity of the system itself in realization of grant. The realization of grant must consider from the whole system. There are two meanings of global grant. Firstly the system can transmit the update to all relative server nodes in the system when someone executes grant (or revoke) operation one time. Secondly if a user passes the authentication on one node of the system, he does not need to be authenticated when he accesses the resources on other nodes. Global grant involves the following respects: the global distribution of grant rules, grant check-up mechanism, the means of updating grant rules and the transmitting of updating. It's the thesis's purpose that how to combine them to an organic whole to complete global grant together while meeting the system requirements such as high availability. After studying relative technologies, the thesis proposes a global grant mechanism based on global consistent grant tables to realize global grant, and give a design on the basis. Finally there is a realization in the thesis. All these are based on special distributed and parallel database system——DPSQL(Distributed and Parallel SQL). Considering the requirement of DPSQL such as high availability and some characteristics of DPSQL, the strategy that there are global consistent grant rules on every node in the system is adopted in the thesis. These grant rules are storied as grant tables. On the basis of global consistent grant tables, there is a system realization of grant check-up and one time identity authentication. GRANT/REVOKE that is a command in SQL is used to update grant rules. The update is transmitted to all on-line servers at the same time to make all of the nodes'grant tables consistent. This thesis consists of six chapters. In chapter one, there is a summary about database security. And security mechanism of some of contemporary popular RDBMS is analyzed. An introduction about DPDBS and its characteristics is given in chapter two. The chapter three depicts MySQL, which is the prototype of DPSQL, and its rights system. Global grant in DPSQL is designed in chapter four and realized in the following chapter. The performance analysis is made in chapter six. At last there is a conclusion and a view.