Object Identification in Multidatabase Systems

In the Pegasus prototype multidatabase system, the key to the problem of object identity is a differentiation between the view of a data administrator, capturing all the underlying discrepancies and their solutions, and the view of an end user or application, in which only a consistent result is visible. New language constructs with which the administrator can describe solutions to identity problems include underlying and unifying types, the Image function, and producer types.