A heuristics-based approach to query optimization in structured document databases

The number of documents published via the World Wide Web in the form of SGML/HTML has been rapidly growing for years. Efficient, declarative access mechanisms for this type of document-structured documents in general-are becoming of great importance. This paper reports our most recent advance in pursuit of the effective processing and optimization of structured document queries, which are important for large repositories of structured documents. Our methodology emphasizes applying exclusively deterministic transformations on query expressions to achieve the best possible optimization efficiency. A new approach is thus proposed that facilitates the exploitation of the DTD (document type definition) knowledge, structural properties and structure indices of structured documents for the purpose of fast query optimization.