The data dictionary is one of the core components of the Oracle database. It consists of a series of tables and views. These tables and views are automatically created by Oracle when the database is created, and there are system table spaces. When the database is started, the system table space will be automatically online. The owners of these tables and views are is user sys.
The data dictionary stores information about the database, including:
- All oracle user information
- Information about tablespaces and datafiles
- Information about permissions and roles, such as which permissions the user has
- Information about schema objects (such as tables, views, procedures, functions, package triggers, etc.)
- Integrity constraint information
- Spatial distribution and current usage of objects in the database
- Audit information (such as who accesses and modifies objects)
- Other database general information