Propagating Functional Dependency and Normalization Between Relations and XML

Abstract

To combine XML with relations is a hotspot in research field. This paper studies the functional dependency and normalization propagation between relations and XML. First the paper gives the definition of functional dependencies and keys for XML; based on it, the concepts of redundancy and DTD normalization are defined. The paper then discusses the functional dependency propagation between relations and XML. When using a general mapping from relational schema to DTD, the paper shows that all the relational functional dependencies can be preserved in the DTD; and when applying a commonly used method to mapping DTD to relational schema, each functional dependency on relations has a corresponding one in the original DTD. The significance of functional dependency propagation lies in the normalization propagation. The paper proves that using the methods above, if the original relation is in BCNF, the generated DTD is normalized, and if the original DTD is normalized, the generated relations are in BCNF.