Extending the Concepts of Normalization from Relational Databases to Extensible-Markup-Language Databases Model

Abstract

In this study we have studied the problem of how to extend the concepts of Functional Dependency (FD) and normalization in relational databases to include the eXtensible Markup Language (XML) model. We shown that, like relational databases, XML documents may contain redundant information and this redundancy may cause update anomalies. Furthermore, such problems are caused by certain functional dependencies among paths in the document. Our goal is to find a way for converting an arbitrary XML Schema to a well-designed one, that avoids these problems. We introduced new definitions of FD and normal forms of XML Schema (X-1NF, X-2NF, X-3NF and X-BCNF). We shown that our normal forms are necessary and sufficient to ensure all conforming XML documents have no redundancies.