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Primary Note: Overview of Oracle Data Dictionary (Doc ID 1500058.1)

Last updated on FEBRUARY 02, 2022

Applies to:

Gen 1 Exadata Cloud at Customer (Oracle Exadata Database Cloud Machine) - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Cloud Exadata Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Oracle Database Cloud Schema Service - Version N/A and later
Information in this document applies to any platform.


NOTE: In the images and/or the document content below, the user information and environment data used represents fictitious data from the Oracle sample or bulit-in schema(s), Public Documentation delivered with an Oracle database product or other training material.  Any similarity to actual environments, actual persons, living or dead, is purely coincidental and not intended in any manner.

The Oracle Data Dictionary provides the basis for the database, and must be created for the database to be able to function correctly and perform it's tasks.
It consists of a read-only collection of database tables and views containing reference information about the database, its structures, and its users.

The purpose of this Document is to provide an overview of the Oracle Data Dictionary. This note will help customers have a better understanding of the Oracle Data Dictionary.

This is a LIVE document. Work is in progress to improve the quality of the content.


This document applies to the Data Dictionary in a non RAC environment
This note does not discuss any additional features/options installed in the database


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In this Document
 Creating the Data Dictionary
 Contents of the Data Dictionary
 Views with the Prefix CDB_
 Views with the Prefix DBA_
 Views with the Prefix ALL_
 Views with the Prefix USER_
 The Dictionary view
 The Dual table
 Storage of the Data Dictionary
 How Oracle Database Uses the Data Dictionary
 Public Synonyms for Data Dictionary Views
 Cache the Data Dictionary for Fast Access
 Other Programs and the Data Dictionary
 Securing Access to the Data Dictionary
 - Database Health Check
 - DBA_REGISTRY view (in 9.2 and higher)

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