XQuery Optimization Based on Program Slicing *

ABSTRACT XQuery has become the standard query language for XML. The efforts put on this language have produced mature and efficient implementations of XQuery processors. However, in practice the efficiency of XQuery programs is strongly dependent on the ability of the programmer to combine different queries which often affect several XML sources that in turn can be distributed in different branches of the organization. Therefore, techniques to reduce the amount of data loaded and also to reduce the intermediate structures computed by queries is a necessity. In this work we propose a novel technique that allows the programmer to automatically optimize a query in such a way that unnecessary intermediate computations are avoided, and, in addition, it identifies the paths in the source XML documents that are really required to resolve the query