An algebraic approach for incremental maintenance of materialized XQuery views

Abstract

Modern data sources, including structural and semi-structural sources, often export XML views over base data, and at times may materialize their views by storing the XML query result to provide faster data access. It is typically more efficient to maintain a view by incrementally propagating the base changes to the view than by re-computing it from scratch. Techniques for the incremental maintenance of relational views have been extensively studied in the literature. However, the maintenance of views created using XQuery is as of now unexplored. In this paper we propose an algebraic approach for incremental XQuery view maintenance. In our approach, an update to the XML source is transformed into a set of well defined update primitives which are propagated through the XML algebra tree. This algebraic update propagation process generates incremental update primitives to be applied to the result view. We briefly discuss our XQuery view maintenance system implementation. Our experiments confirm that incremental view maintenance is indeed faster than re-computation.