Chapter 4. The Oracle Data Dictionary
When you want to find out the meaning of a word, how it is spelled, or its derivation, what do you do? Generally, you go to the nearest dictionary and look up the word. In the same way, when you want to find out the contents of your database, you go to the data dictionary to look up the information of interest. From a security perspective, you will use the data dictionary to gain information vital to your security implementation. If you are a DBA, you will spend a great deal of your time interacting with the data dictionary to gain information about the various objects with which you must interact. You will use the data dictionary to examine user accounts and user quota assignments, to look up the location of datafiles on your system, and to obtain the information you need to perform your job effectively. As a developer, you will use a different view of the data dictionary to keep track of the schema objects within your application. If you are a casual application user , you might never even see a data dictionary entry directly.
Oracle's data dictionary consists of two layers : the tables that make up the real data dictionary and a series of views that allow you to access the information in the data dictionary. Most of the data dictionary views are written to restrict your access to only the data appropriate for your specific level of privilege. The views have meaningful names along with equally meaningful attribute names . In this chapter, we will examine the following information about the Oracle data dictionary:
What the data dictionary is
How the data dictionary is created
How the data dictionary is structured
What type of information is available
How that information may be used in a security system
For more detailed information, see the Oracle8 Concepts Manual , Release 8.0, Part A58227-01, Chapter 4, "The Data Dictionary."