PathStack: A holistic path join algorithm for path query with not-predicates on XML data

Abstract

The evaluation of path queries forms the basis of complex XML query processing which has attracted a lot of research attention. However, none of these works have examined the processing of more complex queries that contain not-predicates. In this paper, we present the first study on evaluating path queries with not-predicates. We propose an efficient holistic path join algorithm, PathStack1, which has the following advantages: (1) it requires only one scan of the relevant data to evaluate path queries with not-predicates; (2) it does not generate any intermediate results; and (3) its memory space requirement is bounded by the longest path in the input XML document. We also present an improved variant of PathStack that further minimizes unnecessary computations. © Springer-Verlag Berlin Heidelberg 2005.