Data Dictionary

What is Data Dictionary?

• Data Dictionary is a collection of tables.
• All the tables in Data Dictionary is created and maintained by Oracle Server.
• Data Dictionary contains all the database related information.
• All the tables of Data Dictionary are maintained by SYS user.

Which type of information does Data Dictionary holds?

Data Dictionary stored the following type of information:

• all of the user name of Oracle server
• privileges granted to all of the users
• name of the database objects
• table constraints
• information about auditing
  

Views of Data Dictionary:

There are total four types of data dictionary views. They are:

• USER_ :These type of views contain those information which are relates the objects by the user.
• ALL_ : These type of views contain table related information by the user which are accessible to the user.
• DBA_ : These type of views are restricted type of views. Only the people who are DBA, can access those type of views.
• V$ : These views are one of the important view. It includes dynamic performance views, database server performance, memory and locking related information.

Summary of this page:

Data Dictionary is the collection of tables which is created and maintained by Oracle Server and which is maintained by SYS user. There are four types of Data Dictionary view: USER_, ALL_, DBA_ and V$.

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