Query optimization in object-oriented database systems : the REVELATION project

We are exploring a scheme that allows optimizing queries over object-oriented databases with encapsulated behavior. Objects and classes will be able to reveal their behavior in terms of expressions in an algebraic language interpreted by a structural object-oriented database system. An object or class can agree or refuse to reveal its behavior. The structural algebra is richer than relational algebra as it includes operators on complex object collections, and updates and traversals of individual objects. Objects may reveal to the optimizer the structural access paths used by their procedures or cost and other statistics useful for query optimization. The main features of our approach is that the object-oriented user interface language is able to perform general computation and to preserve the encapsulation envelope around classes and types.