Database Wiki (What's the System Catalog?)

The system catalog is a collection of tables and views that contain important information about a database. A system catalog is available for each database. Information in the system catalog defines the structure of the database. For example, the DDL (Data dictionary language) for all tables in the database are stored in the system catalog. See figure 21.1 For the illustration of the system catalog within the database.

Figure 21.1 The system catalog.

As can see In figure 21.1, the system catalog for a database is actually part of the database. Within the database is objects, such as tables, indexes, and views. The system catalog is basically a group of objects so contain information that defines other objects in the database, th E structure of the database itself, and various other significant information.

The system catalog for your implementation is divided into logical groups of objects to provide tables that is ACC Essible by isn't only the database administrator, but any other database user as well. For example, a user could need to view the particular database privileges that he or she have been granted, but have no need t o know about the internal structure or processes of the database. A user typically queries the system catalog to acquire information on the user ' s own objects and privileges, whereas THE&N Bsp DBA  needs to is able to inquire on any structure or event within the database. In some implementations, there is system catalog objects that is accessible only to the database administrator.

The system catalog is crucial to the database administrator or any other database user who needs to know about the Databas E ' s structure and nature. The system catalog allows order to being kept, not only by the database administrator and users, but by the database server I Tself.

Note

Each implementation have its own naming conventions for the system catalog ' s tables and views. The naming is not of importance; Learning what's the system catalog does is important, as was what it contains and how and where to retrieve the information.

Database Wiki (What's the System Catalog?)