XQAD:一种XML查询的算法

XQAD:An Algorithm of Querying on XML

目前已经提出的XML查询的方法大都是直接进行实例一级的查询,如XML文档树遍历及嵌套连接等。这些方法忽视了对XML格式信息的利用,当XML文档较大时,性能就会有明显下降。论文给出了一种直接利用DTD的格式信息对XML进行查询的算法XQAD。根据DTD和路径表达式的特点来减少对实例的访问次数,从而提高性能。XQAD还支持多谓词查询,包括结构谓词和值谓词。最后,用实验的方法同其它算法作比较,并对试验结果进行了分析。

Most of the proposed methods evaluate path expression queries in instance space,i.e.directly facing the XML instances,such as XML tree traversal and containment join ways.Speed of these methods is highly relevant to the amount of instances they process.Therefore,if they run on large scale XML documents,the efficiency will extremely decrease.In this paper,a new algorithm of querying on XML,XQAD,is proposed.According to the features of query and DTD,this algorithm can greatly decrease the times of accessing the instances of nodes to improve the performance.The algorithm supports features not only structural predicates but also value predicates.Finally we give the performance analysis and evaluation.