Implementation and Testing of SBQL Object-Relational Wrapper Supporting Query Optimisation

This paper presents design, implementation and prototype tests of an object-oriented wrapper enabling virtual integration of relational databases to an object- oriented database. The integration process is transparent - the users need not be aware that data are delivered by a relational database. The object-oriented model consists of virtual objects that can be in turn arbitrarily transformed by object-oriented updateable views, according to the virtual repository schema. Virtually transformed relational data can be combined in queries with purely object-oriented data and with data from other wrapped resources. Due to this implementation need more attention for effective query optimisation. The described prototype employs dedicated query rewriting methods so both object-oriented and relational query optimisers can work together. Sample optimisation results and comparisons are presented.