COMPOSITE-OBJECT VIEWS IN RELATIONAL DBMS - AN IMPLEMENTATION PERSPECTIVE

We present a novel approach for supporting Composite Objects (CO) as a n abstraction over the relational data. This approach brings the advan ced CO model to existing relational databases and applications, withou t requiring an expensive migration to other DBMSs which support CO. Th e concept of views in relational DBMSs (RDBMS) gives the basis for pro viding the CO abstraction. This model is strictly an extension to the relational model, and it is fully upward compatible with it. We presen t an overview of the data model. We put emphasis in this paper on show ing how we have made the extensions to the architecture and implementa tion of an RDBMS (Starburst) to support this model. We show that such a major extension to the data model is in fact quite attractive both i n terms of implementation cost and query performance. We introduce a C O cache for navigation through components of a CO. With this technique , the performance of navigation through COs, which has been of a conce rn in RDBMSs in the past, is in fact quite satisfactory. We present ou r practical experience in using this facility. We show that our work o n CO enables existing RDBMSs to incorporate efficient CO facilities at a low cost and at a high degree of application reusability and databa se sharability.