We study optimization methods motivated by logical redundancy and physical independence in mediator-like components. We have identified classes of queries and constraints over complex values with dictionaries, generalizing the relational conjunctive queries and embedded dependencies, as well as many interesting examples of complex value and oodb queries and integrity constraints for which we can show that some important classical results on containment, dependency implication, and chasing extend and generalize.
Dictionaries reflect directly the efficiency of the representation and facilitate cost estimation.
We define and enumerate in a novel manner a search space for query plans that incorporate the physical access structures as views on the logical schema. This makes our method easy to integrate in the important rule-based optimization paradigm, and easy to combine both with conventional techniques and with our previous approach to semantic optimization.