A method and system for storing and retrieving data in an object-relational database system includes receiving a query which results in a request to load a first object. The method also includes identifying relationship types of other objects having a relationship with the first object. Then, the first object and those of the other objects which have a composition relationship with the first object are eager loaded. Those of the other objects which have an association relationship with the first object are marked as fault on demand. Preventing re-faulting of the same object in the same object graph, and trimming of graphs for serialization are also provided.