An object-oriented query language interface to relational databases in a multidatabase database environment

Presents an approach to query processing in a multidatabase system that uses an object-oriented model to capture the semantics of other data models. The object-oriented model is used to construct a global schema, defining an integrated view of the different schemas in the environment. The model is also used as a self-describing model to build a meta-database for storing information about the global schema. A unique aspect of this work is that the object-oriented model is used to describe the different data models of the multidatabase environment, thereby extending the meta-database with semantic information about the local schemas. Structural mappings between the global schema and each local schema are then easily supported. An object algebra provides a query language for expressing global queries, using the structural mappings to translate object algebra queries into SQL queries over local relational schema The object algebra can be used to directly retrieve temporarily-stored data from the object-oriented database or to transparently retrieve data from local sources using the translation process described in this paper