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  • 标题:Processing and Evaluation of Broad Fragments of XPath
  • 本地全文:下载
  • 作者:B.Kiran Kumar ; Mr.Shaik Salam
  • 期刊名称:International Journal of Advanced Research In Computer Science and Software Engineering
  • 印刷版ISSN:2277-6451
  • 电子版ISSN:2277-128X
  • 出版年度:2012
  • 卷号:2
  • 期号:4
  • 出版社:S.S. Mishra
  • 摘要:XML queries typically specify patterns of selection predicates on multiple elements that have som e specified tree structured relationships. The primitive tree structured relationships are parent-child and ancestor-descendant, and finding all occurrences of these relationships in an XML database is a core operation for XML query processing. In this pap er, we develop two families of structural join algorithms for this task: tree-merge and stack-tree. The tree-merge algorithms are a natural extension of traditional merge joins and the recently proposed multi-predicate merge joins, while the stack-tree algorithms have no counterpart in traditional relational join processing. We present experimental results on a range of data and queries using the TIMBER native XML query engine built on top of SHORE. We show that while, in some cases, tree-merge algorithms can have performance comparable to stack-tree algorithms, in many cases they are considerably worse. This behavior is explained by analytical results that demonstrate that, on sorted inputs, the stack-tree algorithms have worst-case I/O and CPU complexities linear in the sum of the sizes of inputs and output, while the tree-merge algorithms do not have the same guarantee
  • 关键词:XML query processing; XPath query evaluation; tree-pattern query; partial tree-pattern query
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