事件约束的时间不确定事件流查询处理

Query Processing over Constraint Event Stream with Uncertain Timestamps

提出两种事件约束的时间不确定事件流查询处理方法.基于可能世界的查询处理方法,根据事件约束的不确定事件查询语义,通过对可能世界的遍历获取查询结果.基于事件约束优先的查询处理方法中,根据事件约束计算其所涉及事件发生时间的联合分布律,进而获得复合查询所涉及事件的边缘分布律,最后利用时间不确定事件查询处理技术进行后续的查询处理.实验证明了2种方法对时间不确定约束事件查询有效.基于事件约束优先查询处理方法的可能世界集规模更小,比基于可能世界的查询处理方法更高效.

Two approaches are proposed to process the constraint event stream with uncertain timestamps.The query processing approach based on possible worlds can obtain the results by scanning the possible worlds according to the semantic of the constraint events.The query processing approach based on constraint event priority calculates the joint probability density of event timestamps, furtherly, calculates the marginal probability density of events in the composited query, and finally processes the query according to the query processing technology for the uncertain timestamp events.Experiments verify that both the query processing approaches for constraint event streams with uncertain timestamps are effective, and due to the smaller possible worlds, the query processing approach based on constraint event priority is more efficient than the query processing approach based on possible worlds.