Jérôme Siméon

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XQuery is not only useful to query XML in databases, but also to applications that must process XML documents as files or streams. These applications suffer from the limitations of current main-memory XQuery processors which break for rather small documents. In this paper we propose techniques, based on a notion of projection for XML, which can be used to(More)
XML has become an important medium for data representation, particularly when that data is exchanged over or browsed on the Internet. As the volume of XML data increases, there is a growing interest in storing XML in relational databases so that the well-developed features of these systems (e.g., concurrency control, crash recovery, query processors) can be(More)
Due to the development of the World Wide Web, the integration of heterogeneous data sources has become a major concern of the database community. Appropriate architectures and query languages have been proposed. Yet, the problem of data conversion which is essential for the development of mediators/wrappers architectures has remained largely unexplored. In(More)
The availability of summary data for XML documents has many applications, from providing users with quick feedback about their queries, to cost-based storage design and query optimization. <i>StatiX</i> is a novel XML Schema-aware statistics framework that exploits the structure derived by regular expressions (which define elements in an XML Schema) to(More)
As XQuery nears standardization, more sophisticated XQuery applications are emerging, which often exploit the entire language and are applied to non-trivial XML sources. We propose an algebra and optimization techniques that are suitable for building an XQuery compiler that is complete, correct, and efficient. We describe the compilation rules for the(More)
The World-Wide Web Consortium (W3C) promotes XML and related standards, including XML Schema, XQuery, and XPath. This paper describes a formalization of XML Schema. A formal semantics based on these ideas is part of the official XQuery and XPath specification, one of the first uses of formal methods by a standards body. XML Schema features both named and(More)
Integrity constraints are useful for semantic specification, query optimization and data integration. The ID/IDREF mechanism provided by XML DTDs relics on a simple form of constraint to describe references. Yet, this mechanism is not sufficient to express semantic constraints, such as keys or inverse relationships, or stronger, object-style references. In(More)
Modern applications (Web portals, digital libraries, etc.) require integrated access to various information sources (from traditional DBMS to semistructured Web repositories), fast deployment and low maintenance cost in a rapidly evolving environment. Because of its flexibility, there is an increasing interest in using XML as a middleware model for such(More)
This document proposes an algebra for XML Query. This work builds on long standing traditions in the database community. In particular, we have been inspired by systems such as SQL, OQL, and nested relational algebra (NRA). We have also been inspired by systems such as Quilt, UnQL, XDuce, XML-QL, XPath, XQL, and YaTL. We give citations for all these systems(More)