Query optimization for structured documents based on knowledge on the document type definition

Declarative access mechanisms for structured document collections and for semi-structured data are becoming increasingly important. Using a rule-based approach for query optimization and applying it to such queries, we deploy knowledge on Document Type Definition (DTD) to formulate transformation rules for query-algebra terms. Specifically, we look at rules that serve navigation along paths by cutting off these paths or by replacing them with access operations to indices, i.e., materialized views on paths. We show for both cases that we correctly apply and completely exploit knowledge on the DTD, and we briefly discuss performance results.