EVALUATING OBJECT-ORIENTED QUERY LANGUAGES

Different query languages have been implemented and others proposed fo r object-oriented database systems. Evaluating and comparing these lan guages has been difficult due to the lack of a frame of reference. Thi s paper establishes such a framework using four dimensions: support of object-orientation, expressive power, support of collections, and usa bility. Each dimension is defined in terms of a number of criteria. Th e criteria are, in turn, explained using example queries written in a concise, expressive, and clear query notation: object comprehensions. These same examples also demonstrate the process of evaluating a query language by showing how the criteria can be assessed. An evaluation b ased on the proposed framework reveals that many well-known query lang uages do not meet all the criteria. The evaluation framework can also be used constructively in improving existing query languages and direc ting new query language design.