How is "encapsulation" realised in object-relational databases? How does this improve on the separation of data and programs in relational databases? What are the advantages and disadvantages of encapsulation?

How is "persistence" realised in object-oriented languages, in relational databases and in object-relational databases? Which sorts of data should always be created as persistent objects, and which should be created as transient objects? What are the differences between persistent and transient data with respect to implementation, storage and usability requirements?

In what aspects does Oracle 9i not comply with the Object-Oriented Database System Manifesto?