A Knowledge-Based Approach to Querying Heterogeneous Databases

Query processing plays a fundamental role in current information systems that need to access independent and heterogeneous databases. This paper presents a new approach to querying heterogeneous databases that maps the semantics of query objects onto database schemas. The sematics is captured by the definitions of classes in an ontology, and a similarity function identifies not only equivalent but also semantically similar classes associated with a user's request. These similar classes are then mapped onto a database schema, which is compared with schemas of heterogeneous databases to obtain entities in the databases that answer the query.