Multiple inheritance is also shown by the AMPHIBIAN_CAR class. Any instances of this class will inherit data and behaviors from both the CAR and the BOAT classes.

It is important to note one very big difference between one-to-many relationships and ISA relationships. The ISA construct does not imply any type of recurring association, while the one-to-many and many-to-many relationships imply multiple occurrences of the subclasses. In the previous example, the entire class hierarchy describes vehicles that are associated with the ITEM entity in the overall database. The fact that a class hierarchy exists does not imply any data relationships between the classes. While one CUSTOMER may place many ORDERs, it is not true that one CAR may have many SEDANs.

Summary

Now that we have completed the physical design issues, we can begin to look at tuning for the entire Oracle instance. Tuning is much more than guaranteeing that your application will have a good design. We must also ensure that Oracle has enough system resources to properly service our requests.