| 摘要: |
| XML数据查询中值匹配查询条件的查询代价估计问题是一种典型的多元素查询条件代价估计问题.它与传统关系型数据库中的多元素查询条件不同,因为XML数据中的值信息分布不仅与其他值信息分布相关,还与XML数据中的结构信息相关,而且当XML数据结构比较复杂时,可能会形成高维元素相关.针对以上问题,提出了一种面向XML数据的基于小波的多维直方图查询代价估计算法,并提出了确定XML数据中以某值元素为主键的相互依赖元组的方法,将值匹配条件改写为多元素查询条件的方法以及结构信息的值化方法.实验结果证明,提出的方法取得了较准确的查询代价估计结果. |
| 关键词: XML 值匹配条件 查询代价估计 |
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| 基金项目:Supposed by the National Natural Science Foundation of China under Grant No.60203007(国家自然科学基金);the National High-Tech Research and Development Plan of China under Grant No.2003AA1Z2110(国家高技术研究发展计划(863));the New Star Plan of Science & Technology of Beijing of China under Grant No.H020820790130(北京市科技新星计划) |
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| A Result Size Estimation Algorithm for Value Predication in XML Query |
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QU Wei-Min,SUN Le,SUN Yu-Fang
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| Abstract: |
| Result size estimation of value predication in XML query is a multiple attributes dependent problem. It is different from the counterpart in relational database, for the multiple attributes in XML involve not only the value data, but also the structural information. To solve the problem, this paper proposes a wavelet-based histogram for the result size estimation of value predication in XML query. It also gives the way to identify the multi-dimensional dependent element set, to rewrite the value predication and value denotation of structural information. Experimental results show that the algorithm achieves on accurate result size estimation for value predication in XML query. |
| Key words: XML value predicate result size estimation |
