Temporal Queries in XML Document Archives and Web Warehouses

By storing the successive versions of a document in an incremental fashion, XML repositories and data warehouses achieve (i) the efficient preservation of critical information, and (ii) the ability of supporting historical queries on the evolution of documents and their contents. In this paper, we present efficient techniques for managing multiversion document histories and supporting powerful temporal queries on such documents. Our approach consists in (i) concisely representing the successive versions of a document as an XML document that implements a temporally grouped data model, and (ii) using XML query languages, such as XQuery, to express complex queries on the content of a particular version, and on the temporal evolution of the document elements and their contents. We show that the data definition & manipulation framework of XML & XQuery can support temporal models and historical queries significantly better than the traditional framework of Relational Tables & SQL. To demonstrate this point, we investigate how to express complex queries on the history of relational tables published as XML data.