Skip to Main content Skip to Navigation
Journal articles

Almost-linear inclusion for XML regular expression types

Dario Colazzo 1, 2 Giorgio Ghelli 3 Luca Pardini 4 Carlo Sartiani 5
2 OAK - Database optimizations and architectures for complex large data
Inria Saclay - Ile de France, LRI - Laboratoire de Recherche en Informatique, UP11 - Université Paris-Sud - Paris 11, CNRS - Centre National de la Recherche Scientifique : UMR8623
Abstract : XML data projection (or pruning) is a natural optimization for main memory query engines: given a query Q over a document D, the subtrees of D that are not necessary to evaluate Q are pruned, thus producing a smaller document D'; the query Q is then executed on D', hence avoiding to allocate and process nodes that will never be reached by Q. In this article, we propose a new approach, based on types, that greatly improves current solutions. Besides providing comparable or greater precision and far lesser pruning overhead, our solution--unlike current approaches--takes into account backward axes, predicates, and can be applied to multiple queries rather than just to single ones. A side contribution is a new type system for XPath able to handle backward axes. The soundness of our approach is formally proved. Furthermore, we prove that the approach is also complete (i.e., yields the best possible type-driven pruning) for a relevant class of queries and Schemas. We further validate our approach using the XMark and XPathMark benchmarks and show that pruning not only improves the main memory query engine's performances (as expected) but also those of state of the art native XML databases.
Document type :
Journal articles
Complete list of metadata
Contributor : Dario Colazzo Connect in order to contact the contributor
Submitted on : Friday, January 3, 2014 - 7:35:35 PM
Last modification on : Thursday, July 8, 2021 - 3:48:17 AM


  • HAL Id : hal-00923690, version 1



Dario Colazzo, Giorgio Ghelli, Luca Pardini, Carlo Sartiani. Almost-linear inclusion for XML regular expression types. ACM Transactions on Database Systems, Association for Computing Machinery, 2013. ⟨hal-00923690⟩



Les métriques sont temporairement indisponibles