A comparative study of functional dependencies for XML

Abstract

Functional dependencies (FDs) have been relatively more intensively studied than other constraints for XML data. Yet there seems to be no consensus on the definition of such dependencies, and all previous definitions capture different types of constraints. In this paper, we survey and compare these XML functional dependencies (XFDs) and propose a new definition of XFD which unifies and generalizes the previous XFDs. We show how our GXFDs can express more constraints and hence can be used to detect more XML data redundancies than those in previous work. © Springer-Verlag Berlin Heidelberg 2005.