分布式数据流查询方案及优化

流式数据库系统是一种新型数据库系统，方便于执行连续数据流查询。许多基于流的应用都是分布式的, 由于输入流速率及其他系统参数如可用的计算资源是易变的，所以一个流查询方案必须能适应这些变化。 提出一种分布式流查询方案并进行了优化，使用元组响应时间及系统吞吐量来评价方案的性能。同时，通过实验和其他方案进行比较，证明了方案是最佳的。

Query scheme and its optimization for distributed data stream

Stream database systems are a new type of database system designed to facilitate the execution of queries against continuous streams of data. Many stream-based applications are inherently distributed, Since input stream rates and other system parmeters such as the amount of abailable computing resources can fluctuate significantly, a stream query plan must be able to adapt to these changes. Propose a distributed stream query plan and optimized, use tuple response time and system throughput to evaluate the performance of plan. Compare with other plan by experiments.Proved this plan is optimal.