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

摘要

Presents an approach to query processing in a multidatabase systemnthat uses an object-oriented model to capture the semantics of otherndata models. The object-oriented model is used to construct a globalnschema, defining an integrated view of the different schemas in thenenvironment. The model is also used as a self-describing model to buildna meta-database for storing information about the global schema. Anunique aspect of this work is that the object-oriented model is used tondescribe the different data models of the multidatabase environment,nthereby extending the meta-database with semantic information about thenlocal schemas. Structural mappings between the global schema and eachnlocal schema are then easily supported. An object algebra provides anquery language for expressing global queries, using the structuralnmappings to translate object algebra queries into SQL queries over localnrelational schema The object algebra can be used to directly retrieventemporarily-stored data from the object-oriented database or tontransparently retrieve data from local sources using the translationnprocess described in this paper