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Abstract : |
We study a mechanism that supports the migration of objects from one class of an OODB to another, thereby enabling us to model the same object playing different roles throughout its lifetime. Object migration may introduce typing conflicts due to the different typing constraints imposed by the classes. We present a coercion-like adaptation process that automatically resolves these conflicts. The process combines re-classification of objects and modification of attributes. We study the computational complexity of the problem, and show that the adaptation process can be performed efficiently in databases with covariant schemas. 1, |
