DTD上的YFilter数据流查询优化算法

为了提高YFilter的查询处理效率,在已有的研究工作和YFilter的过滤技术上,定义了唯一父亲约束的完整性约束,并结合DTD的结构和约束信息优化XPath表达式,这种优化算法是在系统运行前进行的预处理,所以有效地降低了YFilter系统的查询时间和空间复杂度.实验结果表明,优化后查询表达式之间相同的前缀增加了,减少了有限自动机的状态数目,并且有效地加快了YFilter的查询速度.

Query optimizational algorithm for data stream of YFilter on DTD

To improve the efficiency of YFilter,based on the prior works and the characteristic of YFilter,a unique constraint father of integrity constraints is defined,and the optimization of XPath under DTD(document type definition) is also addressed by using structural and constraint information of DTD,because it is processed before the runtime of stream processing,filter time and space consumption in the optimized system YFilter is significantly lower.The experimental results show that optimized can increase common prefixes of query paths which lower memory consumption and effectively accelerate YFilter query speed.