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Lesson 2Overview of Oracle data structures
ObjectiveDescribe the new Oracle data structures.

Overview of Oracle Data Structures

One of the shortcomings of the Oracle7 database was that in following the traditional database model, the number of intrinsic data types and data structures was limited.
For other object-oriented databases at the time, this was not the case.
To remain competitive, Oracle has introduced some new object-oriented features that promise to improve the robustness and the performance of Oracle applications.

New data types and structures in Oracle

With Oracle we see several new and exciting data structures that promise faster performance. These data structure opportunities include:
  1. User-defined data types, sometimes called abstract data types or ADT
  2. Nested tables
  3. Allowing repeating groups in table columns by allowing VARRAY data types in columns
  4. Embedding object ID's inside tables and using them to navigate between tables
  5. Creating aggregate objects that consist entirely of OID's to other tables
Tuning with Data Structures
To master the use of these new data types and features, we must intimately understand how each method functions, and how each may help or impede performance.
The next lesson explores Abstract Data Typing (ADT).

Oracle RDBMS

Oracle Database is an RDBMS that implements object-oriented features such as user-defined types, inheritance, and polymorphism. These characteristics of OO databases is called an object-relational database management system (ORDBMS). Oracle Database has extended the relational model to an object-relational model, making it possible to store complex business models in a relational database.
object-relational database management system (ORDBMS): An RDBMS that implements object-oriented features such as user-defined types, inheritance, and polymorphism.

Schema Objects

One characteristic of an RDBMS is the independence of 1) physical data storage from 2) logical data structures. In an Oracle Database, a database schema is a collection of logical data structures, or schema objects. A database user owns a database schema, which has the same name as the user name. Schema objects are user-created structures that directly refer to the data in the database. The database supports many types of schema objects, the most important of which are tables and indexes. A schema object is one type of database object and several database objects, such as profiles and roles, do not reside in schemas.