XPath的轴连接查询技术研究

Study on Processing Techniques for XPath Axis Join Queries

XML查询处理比较流行的是解决祖先-后代、父亲-儿子关系的“结构连接”,其本身研究的是XPath中/和//轴的查询,不能支持XPath各种轴的查询.故本文扩展了结构连接的含义,进一步提出轴连接查询的定义,同时,基于可支持XPath定位轴的RaP编码,设计了两种轴连接算法:RaPMerge和RaPOneJoin.并通过Shakespeare和XMark两个数据集对两种算法进行了对比测试,表明了RaPOneJoin的查询性能在XPath某些轴的查询上同RaPMerge相比有很大的性能优势.

In the field of processing XML queries, the focus of research has been mostly on how to compute ancestor-descendant （//） and parent-child（/） queries using the structure join method. But it can handle the queries based on the XPath＇s child and descendant-or-self axies than on the other XPath＇s axises. A new concept of “axis join” is extended based on “structure join”. And based on RaP numbering scheme, two axis join algorithms named RaPMerge and RaPOneJoin are proposed. Finally, we report experimental studies to investigate the performance based on the Shakesoeare and XMark benchmarks.