The Semi-join Query Optimization in Distributed Database System

【摘要】：In distributed database system,the distributed deposition and redundancy data brought convenient to fault recovery,but they make distributed query processing more complicated at the same time.Query optimization and processing is one of the key technologies in distributed database system.It generally uses semi-join operation to improve the time response performance of query and reduce communication cost.This paper briefly described the corresponding concepts and characteristics of distributed database system,summarized the goals of distributed database query optimization,and analyzed the query optimization process based on semi-join operation combined with the practical application.In addition,it introduced a classical algorithm which is used for multiple connection and query optimization based on the semi-join query optimization,the SDD-1 algorithm.