Projection for Nested Word Automata Speeds up XPath Evaluation on XML Streams

We present an evaluator for navigational XPath on Xml streams with projection. The idea is to project away those parts of an Xml stream that are irrelevant for evaluating a given XPath query. This task is relevant for processing Xml streams in general since all Xml standard languages are based on XPath. The best existing streaming algorithm for navigational XPath queries runs nested word automata. Therefore, we develop a projection algorithm for nested word automata, for the first time to the best of our knowledge. It turns out that projection can speed up the evaluation of navigational XPath queries on Xml streams by a factor of 4 in average on the usual XPath benchmarks.

• Type: Journal
• Year: 2016
• Where: SOFSEM
• Authors: Tom Sebastian, Joachim Niehren
• Keywords: SOFSEM 2016, Theoretical Computer Science