ORATC: Introduction to Oracle Concepts

This is a brief introduction to Oracle Concepts for the DBA. Conceptually, you can think of an Oracle database as nothing more than a large electronic filing cabinet, a place to store and retrieve information. At the computer level, Oracle is a computer program that manages an electronic filing cabinet.

What is an Oracle Database?

A database is a collection of data. An Oracle database holds its data in a coordinated set of files stored on disk, including following types:

Parameter Files - The Oracle Parameter File (PFILE or SPFILE) holds initialization parameters which indicate where the control files are, how memory is allocated, how logging is performed, and other characteristics of the Oracle instance.
Control Files - The Control File stores information needed to verify that the database is consistent, including a list of all database files making up the instance and other important data.
Redo Log Files - The Redo Log files store a sequence of entries describing all actions taken against the database. This data is used to recover a database in the event of instance failure.
Data Files - The Data Files contain blocks of data which store database objects (e.g., tables, indexes, materialized views, etc.) in the database.
Temp Files - The Temp files contains data used temporarily including intermediate results, sort results and so forth.

Duties of Database Administrators

The principal responsibility of a database administrator (DBA) is to make enterprise data available to its users. DBAs must work closely with the developers to ensure that their applications make efficient use of the database, and with system administrators to ensure that physical resources are adequate and used efficiently.

Oracle DBAs are responsible for understanding the Oracle Database architecture and how the database works. DBAs can expect to perform the following tasks:

Installing, upgrading, and patching Oracle Database software
Designing databases, including identifying requirements, creating the logical design (conceptual model), and physical database design
Creating Oracle databases
Developing and testing a backup and recovery strategy, backing up Oracle databases regularly, and recovering them in case of failures
Configuring the network environment to enable clients to connect to databases
Starting up and shutting down the database
Managing storage for the database
Managing users and security
Managing database objects such as tables, indexes, and views
Monitoring and tuning database performance
Investigating, gathering diagnostic data for, and reporting to Oracle Support Services any critical database errors
Evaluating and testing new database features

The types of users and their roles and responsibilities depend on the database environment. A small database may have one DBA. A very large database may divide the DBA duties among several specialists, for example, security officers, backup operators, and application administrators.