Object Views:

While Oracle's object extensions offer rich possibilities for design of new systems, few Oracle shops with huge relational databases in place will want or be able to completely re- engineer those systems to use objects. In sequence to permit established applications to take benefits of these new features over time, Oracle8 gives object views. With object views, you can achieve the subsequent advantages:

Efficiency of object access. Within PL/SQL and particularly in OCI (Oracle Call Interface) applications and object programming constructs provide for convenient retrieval, updating, and caching of object data.   These   programming   services   can   gives   performance improvements, with the added advantages that application code can be more succinct.

Ability to navigate using REFs. Through designating unique identifiers as the basis of an object identifier (OID), you can reap the advantages of object navigation. Example for, you can retrieve attributes from associated "virtual objects" using dot notation rather than explicit joins.

Easier schema evolution. In the early versions of Oracle8, the pure object approach renders almost any type of schema modify at best ugly. By comparing, object views offer more ways that you can modify both table structure and object type definitions of an existing system.

Consistency with new object-based applications. If you required extending the design of a legacy database, the new elements can be implemented in object tables; new object-oriented applications needed access to existing data can employ a consistent programming model. The legacy applications can continue to work without changing.

Other new categories of Oracle can improve the expressiveness of any kind of view, not just object views. Two features that are not strictly limited to object views are collections and INSTEAD OF triggers. Now suppose two relational tables with a simple master-detail relationship. By using the Oracle objects option we can portray the detail records as a single non-scalar attribute (collection) of the master that could be a very useful abstraction. Additionally, using INSTEAD OF triggers, you can tell Oracle accurately how to perform inserts, deletes, and updates on any view. Those two features are available to both object views and non-object views.