When you first install Advanced SQL Engine, it has only one user. This user is called DBC, and from it all other future databases and users in the system are created.
User DBC also initially owns all the space in the entire system. As you create new databases and users, any permanent space you grant them is subtracted from available permanent space in user DBC. Because all space ultimately comes from user DBC, user DBC owns all database objects.
User DBC contains data like a database, but unlike a database it has a password. The usable (PERM) disk space in DBC initially reflects the entire system hardware capacity, minus space for the following system users, databases, and objects:
- All the space available for your databases, users, journals, data tables, indexes, stored procedures, functions, and temporary tables. DBC owns all unallocated space.
- Crashdumps user
- SysAdmin user
- Sys_Calendar database
- TD_SYSFNLIB database
- SQLJ, SYSLIB, and SYSUDTLIB databases for external routines and user-defined types. For more information, see Teradata Vantage™ - SQL External Routine Programming, B035-1147.
- SYSSPATIAL database for geospatial data types. For more information, see Teradata Vantage™ - Geospatial Data Types, B035-1181.
- DBCExtension database for Global and Persistent (GLOP) sets. For more information, see “DBCExtension Tables” in Teradata Vantage™ - Data Dictionary, B035-1092.
- SystemFE user for field engineers
- TDPUSER user
- The system Transient Journal (TJ) which stores the before-change image of every data row involved in a transaction, the row ID of every inserted row, and other control records used by the system to automatically recover data from transaction aborts or to complete transactions.
- The system catalog tables of the Data Dictionary and the suite of user-accessible views defined on those tables (for more information, see Teradata Vantage™ - Data Dictionary, B035-1092).
This also includes a suite of special system query logging tables used to store query logging rules and data when you enable the DBQL feature. See Tracking Query Behavior with Database Query Logging: Operational DBAs.
The setting of DefaultCharacterSet in the DBS Control utility determines the default character set for user DBC. For information on changing the character set for user DBC, see Default Server Character Sets.
Never alter the privileges for user DBC. Changing DBC privileges may cause installation, upgrade, maintenance, or archive procedures to end abnormally and consequently require Teradata Support to correct the problem.
If you use MODIFY USER to change the default character set for user DBC, user-defined functions may no longer work for this user without being recompiled, you must rerun the DIPUDT and DIPDEM scripts, and site-defined functions that use SQL_TEXT must be recompiled.