Database Of Digital Organisms Distributed Query Optimization And Distributed Transaction Processing

With the development of computer networks and information technology, Distributed Database Systems has become one of the research hotspots of computer science. Of storage and query data require high reliability and speed, and increasingly high demand, the limitations of traditional database has been exposed more and more obvious. Distributed database will therefore meet the demand.It is well known that the performance of a distributed database relies heavily on the efficiency of query execution. To obtain efficient query execution, optimization is the most important step. Many researches have carried on research on this subject by going deep into the bottom of Query Engine. Its core idea is to query the compiler to use metadata and data about the statistical data to determine which sequence is the fastest possible. Many mature technologies on this level have been brought out, such as the physical query plan from the bottom of the disk input and output to the syntax analysis phase of the syntax analysis tree, the relational algebra law, the improved logical query plan, the cost estimation of operation, the selective plan based on cost and order of joint, etc. Although many methods have been tried out, no remarkable result or noteworthy technology has come to reality because of complexity of data decomposition and network effects.Since the complexity of distributed database itself, it involves many factors and is very dynamic. Distributed database systems existing in the network environment, communication cost between node and deal with distributed computing has become an important element that can not be evaded. This article concentrates on how to optimize the global query at an upper level: database-level distribution. Based on statistical methods, the optimizing algorithm try to find a light-loaded server that can process the query with less cost. In fact, it uses the historical records of previous execution. Then, according to some algorithm, the optimizing processor can determine which node among the system is the best to execute this query. Distributed Transaction at the implementation process, a copy of the real-time synchronization between the execution and transaction speed is critical, distributed transaction statement is very difficult to guarantee the implementation in different environments can produce the results exactly the same. To solve this problem, the article use MYSQL binary log mechanism to synchronize the other repetition. Because the binary log include all relating information of the implementation, so that in different environments, the same matters would also ensure the implementation of the same results.The balance of this thesis is organized as following: the first chapter reviews the progress of the Distributed Database. The second chapter discusses the DOS_SQL. In third chapter, we introduce the optimization of distributed query. The forth chapter discusses the distributed transaction process. Then, in the next chapter, the implementation details are discussed. The last chapter analyzes the algorithm performance, and then draws the conclusion.