XQuery语言部分求值技术与实现

介绍了XQuery语言的一种部分求值技术及其实现方法,为XQuery语言的实现与应用提供了一种新的程序优化技术.这种离线式部分求值可以大致分为2个阶段:预处理阶段和例化处理阶段.其中,预处理阶段通过引用敏感性分析和绑定时间分析来分析参变量在程序中的传播和运算过程,为处理阶段例化处理设定作用范围;例化处理阶段完成程序的自动例化,生成滞留程序且提供了编译时和运行时2种例化方式的支持.基于以上技术研制的一个XQuery部分求值原型系统已经实现,通过对若干XQuery查询案例进行测试,结果表明,经过XQuery部分求值技术处理后能够有效地提高其查询的执行效率.

The Research and Implementation of Partial Evaluation for XQuery

In this paper, we present the research and implementation of off-line partial evaluation for the XQuery language. The main partial evaluation process includes two phases, that is, preprocessing phase and specialization phase. Using the reference-sensitivity analysis and a two-stage binding-time analysis, the former phase gives the necessary control or range information for processing phase to direct program specialization.The latter phase finishes the program specialization and generates residual program for source XQuery program, and it supports both compile-time specialization and run-time specialization. On the basis of this technique, a prototype of partial evaluation system for XQuery has been implemented, and the results of experiments show that the speedups of XQuery residual programs that have obtained are good.