面向NXD的XML数据函数依赖

XML的半结构化特性造成了Native XML 数据库中数据模式规范化设计中的很多问题.采用结构信息和数据信息相结合的方法,给出XML数据间函数依赖的定义,解决数据模式规范化设计中的理论问题.建立了XML模式路径和XML数据树节点路径的定义,描述XML数据中的路径;给出了XML文档有效性的形式化定义;在此基础上定义了树元组和树元组相等的概念.运用树元组及其相等的概念定义了XML数据的函数依赖关系,进而给出了相应的自反、增广、传递推理规则,用于推导给定集合所蕴涵的函数依赖关系.并证明了这一推理规则是正确的.上述工作为Native XML 数据库系统中数据模式的规范化设计提供了一定的理论基础,增强了XML数据的语义特性.

XML functional dependency on NXD

As semi-structured data, XML brings some problems in the normali zation of Native XML Database data schema. To solve the problems, the method of combination of xml structure information and xml data information was proposed, and by using this method the concept xml functional dependency was defined. The con cept of xml schema path, xml tree node path and the formalization of a validated xml document were studied. On the basis of these concepts, the definition of tr ee tuple and equation of tree tuple were constructed. As a result, the definitio n of xml functional dependency was proposed on the basis of above-mentioned con cepts. The inference rules about xml functional dependency includes reflectivity, augmentation and transitivity were proved to deduce the implicati on of xml functional dependency in a given sets. The rules were proved right. Our w ork provides some theory basis of the normalization of native XML database data schema, and also enhances the semantic of xml data.