XML and relational data: towards a common model and algebra

In this paper we present a model for the management of relational, XML, and mixed data. The main high-level approaches to manipulate XML, i.e., SQL/XML, XQuery, and object/relational XML columns, can all be based on our common model and algebra. Our query algebra, yet very simple, can represent queries not expressible by other proposals and by the current implementation of TAX. Moreover, we show that relational-like logical query rewriting can be extended to our algebraic expressions.