Performance evaluation of the object-relational transformation methodology

The emergence of the object-oriented (OO) methodology has shown its capabil ities in modelling the real world better than the earlier relational method ology. However, object-oriented databases (OODBs) are still considered imma ture in comparison with relational databases (RDBs) which have existed for many years. RDBs still continue to dominate the implementation of databases constituting more than 90% of all database implementations [28]. It was fe lt worthwhile to exploit the great modelling power of OO methodology, while still facilitating relational implementations. These reasons have led us t o develop an object-relational transformation methodology [20-25] which all ows us to use the OO methodology for data modelling and to transform it int o a relational logical model for implementation in relational database mana gement systems (RDBMSs). The main purpose of this paper is to present a per formance evaluation of the transformation methodology. The evaluation cover s I/O cost models of different types of queries. The type of evaluation is basically comparison-based, in which the performance of SQL operations upon a set of tables derived from the relational data model is compared with th e tables derived from the OO data model using the transformation methodolog y. The results of the evaluation show that the performance of the RDB imple mentation transferred from an OO conceptual model using our object-relation al transformation methodology is better than the relational implementation using a conventional relational modelling. Moreover, in many cases, the rel ational modelling is not applicable since it cannot capture the design sema ntics particularly relating to collection types. Our object-relational meth odology solves this problem. (C) 2001 Elsevier Science B.V. All rights rese rved.