Selection of nodes for distributing relations in parallel database

In parallel database system, a good data placement could improve execution efficiency of multi-join queries greatly. The bandwidth of network communication is always the bottleneck of parallel database system based on PC clusters. Data communication among nodes would bring more time cost when executing join operations. This paper proposes selection of nodes algorithm, which takes the data redistribution into consideration and reduces additional communication cost. Furthermore, it takes into account intra-operator parallelism, independent inter-operator parallelism and pipelined parallelism in order to develop parallelisms of PC clusters system. The result of experiment indicates the algorithm has good performance and contributes to promoting execution efficiency of parallel multi-join queries.