Evaluating structural summaries as access methods for XML

Structural summaries are data structures that preserve all structural features of XML documents in a compact form. We investigate the applicability of the most popular summaries as textitaccess methods within XML query processing. In this context, issues like space and false positives introduced by the summaries need to be examined. Our evaluation reveals that the additional space required by the more precise structures is usually small and justified by the considerable performance gains that they achieve.