【摘要】 针对XML数据查询的核心操作-树模式查询,提出基于XML Schema约束来优化树模式查询的方法。该方法提出了统一的优化规则描述语言ORS的语法与语义。ORS描述的优化规则中包括对树模式条件的描述、对XML Schema条件的描述以及在满足前两个条件下应该输出的动作。根据ORS语言描述的优化规则以及待处理的树模式,系统会自动输出该树模式的优化动作。该方法一方面简化了树模式优化的过程,另一方面把模型检查技术运用到XML树模式查询优化上,利用时态逻辑公式描述优化规则中的约束条件,利用模型检查的方法提取XML Schema的约束,对ORS语法和语义的严格定义确保了生成的优化动作的正确性。更多还原

【Abstract】 For the core operation of XML data query,tree model query,a general method based on the constraints in XML Schema is proposed. This method presents a unified optimization rule to describe the syntax and semantic of the language ORS. The optimization rule of describing ORS includes the description of the tree model condition,the description of XML Schema condition and the action that should be output when meet the first two conditions. According to the optimization rules describing ORS and the tree model to be processed,the system will output the optimized actions automatically. On the one hand,this method simplifies the process of optimizing the cutting process of tree model. On the other hand,model checking technique is applied to the XML tree model query optimization. The constraint conditions of the optimization rules are described by the temporal logic formula. Using the model checking algorithm to extract the constraints of XML Schema,and the strict syntax and semantics definition of ORS ensures the correctness of the generated optimal actions.更多还原