Constraints-Preserving Mapping Algorithm from XML-Schema to Relational Schema

摘要

XML is fast emerging as the dominant standard for representing data in Internet, so there are increasing needs to efficiently store it. One potential path to this goal is transforming XML data into relational database. But exiting XML-to-RDB algorithms focus only on the structure and largely ignore semantic constrains, in addition, their inputting is DTD rather than XML-Schema, which is recommended by W3C as the standard of XML Schema language. In this paper, we present an algorithm for mapping XML-Schema to relational schema. Our main ideas are as follows: 1) On the basis of regular tree grammar, propose a concise and precise formalization representing method for XML-Schema, FD-XML, which can perfectly drive and describe structure as well as semantic constraints from a given XML-Schema; 2) Extend the traditional entity relational model to HER (Extended Entity Relational model); 3) Map FD-XML to EER and then EER to relational schema. During the mapping, both data structures and semantic constrains are correctly preserved to relational schema. With the above procedures, the mapping algorithm comes into being. Based on the algorithm, XML data is stored into relational database. Experiment results are also presented.