基于部分求值的Twig查询优化

Twig Query Optimization Based on Partial Evaluation

Tree Match算法是一种有效的Twig查询匹配算法,但其存在反复分析Twig模式的缺点。针对该问题,引入编译中的部分求值技术,提出一种Twig查询优化方案。通过部分求值提前完成对Twig模式的分析,生成查询专用的指令序列代替原查询程序,并给出查询机执行引擎,从而消除重复计算,优化XML树模式查询过程。实验结果表明,在不同Twig模式下,该优化方案能够有效提高XML查询的执行效率。

Tree Match algorithm is widely considered to be an effective Twig query algorithm. According to the disadvantage of Tree Match algorithm ＇s repeated analysis on Twig pattern,partial evaluation technology in the field of compilation is applied,and a Twig query optimization scheme is proposed. Analysis on Twig pattern is completed ahead of scheduling through partial evaluation,generating instruction sequences for query to replace the original query program,and a special execution engine of query machine is provided,thus eliminating repeated calculation and optimizing the e Xtensible Markup Language（ XML） tree pattern query. Experimental results showthat the proposed optimization scheme can effectively improve the execution efficiency of XML query in different Twig patterns.