Optimization of Join Queries on Distributed Relations Using Semi-Joins

The processing and optimizing a join query in distributed database system using sequence of semi-joins has been done by using semi-join based algorithm. The main objective of this kind of algorithm is to predict the best execution plan for a join query retrieving data from two or more remote computers.To accomplish this, the two major components are query rewriter and query optimizer, but we focus on query optimizer part, particularly, on cost based query optimization. The algorithm which has been used to optimize a join query is SDD-1 algorithm, which uses semi-joins concept extensively. The objective function of SDD-1 is to minimize total communication time.