A resource efficient hybrid data structure for twig queries

Abstract

Abstract. Designing data structures for use in mobile devices requires attention on optimising data volumes with associated benefits for data transmission, storage space and battery use. For semistructured data, tree summarisation techniques can be used to reduce the volume of structured elements while dictionary compression can efficiently deal with value-based predicates. This paper introduces an integration of the two approaches using numbering schemes to connect the separate elements, the key strength of this hybrid technique is that both structural and value predicates can be resolved in one graph, while further allowing for compression of the resulting data structure. Performance measures that show advantages of using this hybrid structure are presented, together with an analysis of query resolution using a number of different index granularities. As the current trend is towards the requirement for working with larger semi-structured data sets this work allows for the utilisation of these data sets whilst reducing both the bandwidth and storage space necessary.