基于代价的XML Schema到关系模式的映射策略研究

A Mapping Strategy from the XML Schema to the Relational Schema Based on Query Cost

XML作为一种数据交换的国际标准,已经广泛应用于各个领域,如何准确地实现XML与关系数据库的转换已经成为一个重要的研究课题。本文主要研究XML Schema到关系模式的映射方法,通过对XML Schema的结构和语法进行分析,提取元素的语义信息,找到真正的复杂类型的元素,将XML Schema转换为E_Schema,E_Schema表达方式简单且信息完整,结合基于查询代价的思想对E_Schema进行处理,得到最优模式,再将其转换成关系模式,而且能保持原有的层次关系,从而实现了一个更为简单、完善的映射方案。

As an international standard of data exchange over the Web, XML has been applied in many fields. How to transform the XML document to the relational database is an important research topic. The paper studies the method of mapping the XML schema to the relational schema. After analysing the structure and syntax of the XML schema, extracting the semantic information of elements, finding the real complex type elements, the XML schema is transformed to E Schema . The expression of E_schema is simple but complete. E_Schema is processed based on query cost, and the best schema is obtained, and then converted to the relational schema which keeps the original hierarchical relation. Finally a simple and exceltent mapping scheme is implemented.