Basic Introduction to five aspects of Oracle Data Dictionary

Oracle Data dictionary is the most important component of Oracle Database. It is the place where Oracle stores information about the database. It is used to describe data and provides the system information of the database, and information about the routine.

1. Concepts of Oracle Data Dictionary

Data dictionary is the Core Component of Oracle Database. It consists of a series of read-only data dictionary tables and data dictionary views. The data dictionary table records the system information of the database, such as the information of the solution object, the performance information of routine running, such as the status of the routine, and the information of the SGA area ). The data dictionary expression owner is a SYS user. Both the data dictionary table and the data dictionary view are saved in the SYSTEM tablespace. Therefore, we recommend that you do not create other solution objects in the system tablespace for performance and security reasons.

The data dictionary mainly stores the following information:
1) Definition information of various solution objects, such as tables, views, indexes, synonyms, Introduction, stored procedures, functions, packages, triggers, and various objects.
2) storage space allocation information, such as how much storage space is allocated to an object and how much storage space the object uses.
3) security information, such as account, permission, role, and Integrity Constraint information.
4) performance and Statistics during routine operation.
5) Basic information of other databases.

2. The Oracle Data dictionary includes:

1) information about all schema objects in the database, such as tables, views, clusters, and indexes.
2) How much space is allocated and how much space is currently used.
3) column default value.
4) Constraints on information integrity.
5) name of the Oracle user.
6) permissions granted to users and roles.
7) Audit information accessed or used by users.
8) Other generated database information.

3. The main usage of Oracle Data Dictionary is:

1) Oracle queries a data dictionary table or data dictionary view to obtain related users and solution objects. Object definition information and other storage structure information, so as to confirm the permission, the existence and correctness of the solution object.
2) After each DDL statement is executed to modify the schema object and object, Oracle records the changes in the data dictionary.
3) You can obtain various information related to solution objects and objects from the read-only view of the data dictionary.
4) DBA can monitor the running status of the routine from the dynamic performance view of the data dictionary to provide a basis for performance adjustment.

4. Oracle Data Dictionary Composition

For ease of use, the information in the data dictionary is organized through tables and views. A data dictionary consists of a data dictionary table and a data dictionary view.

5. Oracle Data dictionary table

All information in the data dictionary table is actually saved in the data dictionary table. The information stored in the data dictionary table is usually encrypted. A data dictionary table belongs to the SYS user. You can create a data dictionary table by automatically running the SQL. BSQ script when creating a database. Most data dictionary tables contain special symbols such as $.

1. Oracle Data Dictionary usage
2. Oracle Data Dictionary description
3. Usage of Oracle Data Dictionary
4. Which views are included in the Oracle Data dictionary?
5. Oracle Data Dictionary practices