The database manager maintains a set of views and base tables that contain information about the data under its control. These views and base tables are collectively known as the catalog. They contain information about objects in the database such as tables, views, indexes, packages and functions.
The catalog views are like any other database views. SQL statements can be used to look at the data in the catalog views in the same way that data is retrieved from any other view in the system. The database manager ensures that the catalog contains accurate descriptions of the objects in the database at all times. A set of updatable catalog views can be used to modify certain values in the catalog (see Updatable Catalog Views).
Statistical information is also contained in the catalog. The statistical information is updated by utilities executed by an administrator, or through update statements by appropriately authorized users.
The catalog views are listed in Appendix D, Catalog Views.