D-sql Distributed Database System Startup And Recovery

Alonging with the extensive application of distributed database system and the improvement of the computer and network technology, distributed database system (DDBS) has become an important field of information processing.A distributed database system consists of user interface subsystem, directory management subsystem, compile subsystem, distributed transaction management and concurrency control subsystem, data implement system, recovery subsystem etc. And recovery subsystem is generally accepted as an essential part of distributed database system. It takes charge the startup and recovery process of distributed database system and makes sure that fault database site could recover from fault state to guarantee the consistence of the database.The startup and recovery process is very complex in distributed database system. When the process begins, recovery subsystem initializes the whole distributed database system, then collects node information to create database directory, and rebuilds the consistent database according to the database directory.On the basis of deeply researching in distributed database system, this paper designs and implements the startup and recovery process of distributed database system D-SQL. Especially, a new algorithm of log recovery based on consistent global checkpoint in distributed database is presented in this paper. In the algorithm, neither checkpointing nor recovering will affect other normal database activities, which guarantees the availability of distributed database.The paper is organized as follows. Section 1 overviews the history of distributed database. Section 2 introduces the startup and recovery process of distributed database system. Section 3 describes the structure of D-SQL. Section 4 presents the implementation of startup process in D-SQL. Section 5 shows the design of recovery process in D-SQL. Section 6 introduces the new definition of consistent global checkpoint, then derives the algorithm and provides the proof of correctness. Section 7 discusses the performance of D-SQL. Finally, Section 8 concludes the paper.