optimizing xpath queries using composite axes

Abstract

In this thesis, we have designed the specialized navigationalaxis SNA, which can be used to rewrite an input query to access much fewer elementsto compute the evaluation results. At the same time, we havedesigned the novel composite axis Region Axis RA, which ismainly used for rewriting the wildcard steps in XPath queries, whoseevaluation is generally expensive. By rewriting with both SNA and RA, an optimized query not only has fewer steps, but the composite-axis steps can also bemore efficiently evaluated than the replaced steps. We haveconducted comprehensive experiments and the results demonstratesignificant performance improvement using our proposed optimizationand evaluation techniques.