Requêtes arbres régulières pour l'analyse de dépendances entre vues et mises à jour de documents XML
Résumé
In this paper we study the classical problem of the impact of an update on a view defined over semi-structured data. We adopt the following working hypotheses: (i) the source document is modeled by an unranked, labeled, ordered tree, (ii) a view V is a tree query whose evaluation on the source document provides a desired partial view of the document, (iii) a class of updates C. is also given by a tree query selecting the nodes to modify. We then study the following problem: given a view query V and a class of updates C., is it possible to detect if the view V is independent of each update q in C.? We show that the problem is in general PSPACE-hard. We propose a sufficient condition evaluable in polynomial time ensuring the independence of a view V with respect to a class of updates C.. We then consider the class of linear view queries for which the problem becomes polynomial. We also show that the tree query model chosen to express V and C., is incomparable with XPath but is able to capture positive queries of CoreXPath.