【摘要】 PatternTree(PTQ)是复杂的树状结构,求解PTQ需要在XML文档集合中查找与之匹配的数据。在PTQ中,只有部分节点是需要输出的查询目标节点,其余节点则是中间结果。因此,如何在求解过程中尽量避免中间结果的产生,是XML查询优化面临的一个关键问题。论文提出了一种PTQ分解策略,能够根据不同查询操作的粒度,将PTQ分解为可用一种内部操作实现的最大片断集合。从而有效的限制中间结果的产生,提高查询效率。更多还原

【Abstract】 Pattern tree has complex structure.To evaluate the pattern needs to find all the matching nodes in the XML data.But only some of the nodes of the pattern tree are the target nodes of the query,and the others are intermediate results.It is a key problem on how to decrease the size of the intermediate results and limit the existing periods of the results.In this paper,we present a pattern tree decomposition strategy,which can decompose the Pattern tree into the set of the largest parts based on the query granularity.Each part can be dealt with just one query operation.The experiments indicate the query efficiency can be promoted by avoiding the unrelated intermediate results.更多还原