【摘要】 分布式查询是一种需要网络支持且网络通信成本较大的查询过程.查询策略和技术的优劣不但直接影响到分布式查询的通信成本,而且也影响到分布式查询的效果.一种有效的查询策略和技术将大大地节约查询所需的通信成本,缩短查询所需的时间.设计和开发出有效的查询策略和技术是分布式查询面临的挑战.WPERF+连接算法是一种新的分布式查询算法,它结合了W算法和PERF算法的特点,进一步强化了W算法和PERF的性能.理论上可以证明,WPERF+算法与W算法相比较,在不增加计算复杂性的情况下,具有更低的分布式查询处理成本.更多还原

【Abstract】 Distributed query is a query process that will incur heavy communication cost. The basic challenge is to design and develop efficient query strategies and techniques to minimize this communication cost. An efficient optimization algorithm for distributed query,i.e.,WPERF+,was presented in this paper. The advantages of W semi joins and PERF joins had been combined into WPERF+,and greatly enhanced the performance of W semi joins and PERF joins. It is theoretically proved that WPERF+strategy is an efficient optimization algorithm that can greatly reduce its communication cost of distributed query.更多还原