We study XML stream-specific schema-based optimization. We assume a widely-adopted automata-based execution model for XQuery evaluation. Criteria are established regarding what schema constraints are useful to a particular query. How to apply multiple optimization techniques on an XQuery is then addressed. Finally we present how to correctly and efficiently execute a plan enhanced with our SQO techniques. Our experimentation on both real and synthetic data illustrates that these techniques bring significant performance improvement with little overhead.
Hong Su, Elke A. Rundensteiner, Murali Mani