Efficient XQuery rewriting using multiple views

We consider the problem of rewriting XQuery queries using multiple materialized XQuery views. The XQuery dialect we use to express views and queries corresponds to tree patterns (returning data from several nodes, at different granularities, ranging from node identifiers to full XML subtrees) with value joins. We provide correct and complete algorithms for finding minimal rewritings, in which no view is redundant. Our work extends the state of the art by considering more flexible views than the mostly XPath 1.0 dialects previously considered, and more powerful rewritings. We implemented our algorithms and assess their performance through a set of experiments.