XSQ

Abstract

We have implemented and released the XSQ system for evaluating XPath queries on streaming XML data. XSQ supports XPath features such as multiple predicates, closures, and aggregation, which pose interesting challenges for streaming evaluation. Our implementation is based on using a hierarchical arrangement of augmented finite state automata. A design goal of XSQ is buffering data for the least amount of time possible. We present a detailed experimental study that characterizes the performance of XSQ and related systems, and that illustrates the performance implications of XPath features such as closures.