The management of temporal data is a crucial issue in many applications. Recently, XML has become the standard for data exchange and representation. Consequently, important efforts have been made on the development of temporal extensions for XML. This paper investigates how to generate or maintain space-efficient time-stamped documents. We formally define a notion of compactness which allows for comparing documents. Then, we present two methods. For the first one, called general method, no restriction is made on the evolution of the XML documents whereas for the second one, called update-based method, changes are assumed to be specified by updates. For both methods, the issue is to enable processing very large documents, to use existing engines and to comply to Xquery Update Facility. The two methods are compared in terms of space-efficiency. The update-based method produces time-stamped XML documents that are more satisfactory wrt space-efficiency than the general method. This goes to show that the update-based method effectively takes advantage of the updates.

This paper presents a novel static analysis technique to detect XML query-update independence, in the presence of a schema. Rather than types, our system infers chains of types. Each chain represents a path that can be traversed on a valid document during query/update evaluation. The resulting independence analysis is precise, although it raises a challenging issue: recursive schemas may lead to infer infinitely many chains.A sound and complete approximation technique ensuring a finite analysis in any case is presented, together with an efficient implementation performing the chain-based analysis in polynomial space and time.

Abstract. The goal of this article is to show that, in the context of XML data processing, information conveyed by schema or XML types is a powerful component to deploy optimization methods. We focus on the one hand on recent work developed for optimizing query and update evaluation for main-memory engines and on the other hand on techniques for checking XML query-update independence. These methods are all based on static type analysis. The aim of the article is to show how types rank before constraints for XML data processing and the presentation of each method is kept informal.