Towards a Context-Aware Relational Model

In traditional databases and information systems the number of users is more or less known and their background is to a great extent homogeneous. In distributed and heterogeneous environments however such as the Web, users do not apply the same conventions when interpreting data due to different backgrounds, knowledge or culture. Interpreting and managing data according to the context is a topic not explored in its full potential in these new environments. In this work we present the Context Relational model (CR model), a model that extends the relational model to argue also about context. The interesting part of this approach is that context is treated as first-class citizen at the level of database models and query languages. This is due to the fact that an attribute may not exist under some contexts or that the attribute may have different values under different contexts. Apart from the model description this work presents also a set of basic operations which extend relational algebra so as to take context into account.