Query scheme and its optimization for distributed data stream

Stream database system is a new type of database system designed to facilitate the execution of queries to continuous streams of data.Many stream-based applications are inherently distributed.Since input stream rates and other system parameters such as the amount of available computing resources can fluctuate significantly,a stream query plan must be able to adapt to these changes.This paper proposed a distributed stream query plan and optimized,and defined performance metrics for response time and system throughput.The experimental result proves that this plan is optimal compared with other plans.