Implementing an Object Model on Top of Commercial Database Systems

The aim of the COCOON project is to investi gate the design of an object oriented data model with main emphasis on e cient implementation of queries and updates While the nested rela tional kernel of DASDBS is the target physical storage system for COCOON the model is also implemented on top of commercial database sys tems as rst prototypes and to analyze feasibility and compare performance This report summarizes the experiences of im plementing the COCOON object model and its object algebra COOL on top of two commercially available database systems a relational one Or acle and an object oriented one ONTOS We have chosen a relational one because the state of the art database systems for productive use are still relational and an object oriented one because a couple of companies started to sell object oriented database system products Ini tially we expected a semantic gap between our object model and relational databases and as sumed that the mapping to object oriented data bases is much more straightforward First we describe the mapping of COCOON type and class declarations into Oracle tables and ONTOS C classes Then we investigate the transformation of object retrieval and manipula tion by comparing COOL with Oracle s relational SQL and the SQL like query interface of ONTOS