An Optimized Distributed Query Algorithm for Virtural Database System
He Jia-ying Li Shao-fa (Department of Computer Science & Engineering,South China Univ. of Tech., Guangzhou 510640,China)
Concerning the distributed querying network cost problem of virtual database system (shortened as "VDBMS"),an optimized distributed query algorithm SJQA( Semi-join Based Query Algorithm ) was proposed. In comparison with Max Sub-Query method,this algorithm takes into account the executing sequence of all the Sub-Queries and their way of connection,and thus efficiently reduces the total network cost. Experimental results show that the optimizing benefits from SJQA will increase as the selective factors of the query are smaller,and its optimizing effect on this kind of query is quite obvious.
【CateGory Index】： TP311.13