Transformation Based XML Query Optimization

Abstract

This chapter addresses the fundamental issues of XML query optimization – equivalences and transformation rules. Equivalences are typically used as the basis to pursue transformation-based query optimization in traditional database systems. In this chapter, we develop the conception of equivalences in the context of XML database and XML query optimization. We then propose to derive deterministic transformation rules by incorporating general and XML-specific optimization heuristics to achieve high optimization efficiency for XML queries. We hope the work presented in this chapter will set a preliminary foundation or framework for further in-depth investigation for transformation-based XML query optimization.