Study of query of distributed database based on relation semi join

Query processing and optimization of distributed database are the key factors to affect the performance,service efficiency and reliability of system. On the basis of the study of some common optimization algorithm of distributed query, query optimization algorithm based on multi-relation semi join is put forward to apply to this situation that takes buffer zone of distributed database system as the final assembly station of intermediate result of query. The experiment proves that query optimization algorithm based on multi-relation semi join obviously reduces the data volume of intermediate result and effectively decreases the overall cost of network communications. Comparing with common multi-relation semi join algorithm, the optimization benefit of the algorithm in this article is higher.