A context-aware preference database system

A context-aware system is a system that uses context to provide relevant information or services to its users. While there has been a variety of context middleware infrastructures and context-aware applications, little work has been done on integrating context into database management systems. In this paper, we consider a preference database system that supports context-aware queries, that is, queries whose results depend on the context at the time of their submission. We propose using data cubes to store the dependencies between context-dependent preferences and database relations and OLAP techniques for processing context-aware queries. This allows for the manipulation of the captured context data at various levels of abstraction, for instance, in the case of a context parameter representing location, preferences can be expressed for example at the level of a city, the level of a country or both. To improve query performance, we use an auxiliary data structure, called context tree. The context tree stores results of past context-aware queries indexed by the context of their execution. Finally, we outline the implementation of a prototype context-aware restaurant recommender.