Distributed And Parallel Database Systems Dp-sql Recovery Mechanism

Distributed and Parallel Database System (DPDBS) is the joint of distributed computing, Parallel Process, and Network technology. It is not only powerful at distributed data management, but also has well performance in parallel processing. With the extension of database application, the DPDBS has obtained more and more recognition. It has become one of the most active and promising research areas of computer science.DP-SQL is a distributed and parallel database system developed by 8010 Research Lab. Based on the most popular open-source database system Mysql, it not only retains the high performance of Mysql itself, but also possesses most virtues of Distributed and Parallel Systems, such as high reliability, high availability, high throughput, large storage capability, etc. The whole system can be divided into four sub-systems, which are user interface sub-system, communication sub-system, server managing sub-system, and distributed and parallel executing sub-system. User interface sub-system locates on clients. It sends queries from the client to a proper server and retrieves results. The communication sub-system provides quality and reliable message passing mechanism for other modules. The server managing sub-system consists of multiple services that make the whole system run well. Finally, the distributed and parallel processing sub-system controls all the details related to execution of all kinds of commands.Recovery from node failures is a critical issue in distributed and parallel database systems. When some failures happen, the database can recover to a consistent state and continue its service with the help of recovery system. Moreover, a database node also requires a recovery process during its startup session, by which it can get consistent with other running nodes in the system.Among the various recovery techniques, log-based recoveries grow popular for their reliability and tolerable overhead. However, in conventional log-based recovery protocols, the nodes providing recovery service may still be overburdened, especially when the recovery is resource consuming. As a result, not only the system performance is compromised, but also the possibility of large-scale failure increases. In this paper, we present an agent-based dynamic recovery protocol. It divides the whole recovery process into three major steps: log-recovery, agent-recovery, andsynchronization. The key idea of this new protocol is to cache new database operations during recovery in agents. All these cached operations can then be replayed independently later. The analysis indicates that the new protocol can improve recovery speed by reducing disk I/O and minimize internode's dependency during recovery. Therefore, system failure rate is cut down and the overall performance gets improved.The balance of this paper is organized as follows. In Chapter 1 we review the progress of research on DPDBS. Then, In Chapter 2 we discuss the features of DPDBS and the conventional recovery mechanisms. Chapter 3 presents the architecture of a quality DPDBS named DP-SQL. Some implementation details are also discussed. Chapter 4 analyzes the recovery system in DP-SQL. In Chapter 5, the Agent-based dynamic recovery protocol is presented. Its proof of correctness, implementation details, and performance analysis are also discussed. The last chapter draws the conclusion and makes expectation for the future research.