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The multiobject mechanism is a pertinent way to implement specialization in an object database and differs from the classical mechanism used in most object-oriented database systems. It supports multiple instantiation, automatic classification and object migration. Consequently it is well suited to take into account schema evolution. It makes schema changes more pertinent, easier to implement, and less expensive than with the classical implementation of specialization indeed. The multiobject mechanism is implemented in the F2 database system which supports schema evolution.

Abstract

One of the fundamental aspects of information and database systems is that they change. Moreover, in so doing they evolve, although the manner and quality of this evolution is highly dependent on the mechanisms in place to handle it. While changes in data are handled well, changes in other aspects, such as structure, rules, constraints, the model, etc., are handled to varying leveis of sophistication and completeness. In order to study this in more detail a workshop on Evolution and Change in Data Management was held in Paris in November 1999. It brought together researchers from a wide range of disciplines with a common interest in handling the fundamental characteristics and the conceptual modelling of change in information and database systems. This short report of the workshop concentrates on some of the general lessons that emerged during the four days.

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