XML Query Optimization Using the Binding Hash Method

XML query processing involves searching an XML document and returning results that satisfy a query while choosing the best method for the particular query and document. In this paper we develop a method called binding hash (BH) that performs a subset of XML query operations focusing on structural join. The BH method answers Xpath expressions directly or generates witness trees that can be used as intermediate results in a query processor. It uses pointer-based traversal and index-based access simultaneously to speed-up structural joins. A performance study indicates that the BH method performs better than existing competitive techniques for queries that are deeply nested and non-bushy. The BH method can be integrated into a larger system to be selected for an execution plan when it achieves the best performance.