Starter Database Contents
Locating Control Files
The starter database contains three control files. These files are located in the ora_root:[oradata.<db_name>] directory. The files control01.ctl, control02.ctl, and control03.ctl are automatically included in the Custom database. Oracle Corporation recommends that you keep at least three control files (on separate physical drives) for each database and set the CONTROL_FILES initialization parameter to list each control file. Table
Table 5–4 Database Control Files
Control Files | Description |
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|
control01.ctl | A control file is an administrative file. Oracle9i requires a |
control02.ctl | control file to start and run the database. The control file |
control03.ctl | records the physical structure of the database. For example, a |
| control file contains the database name, and the names and |
| locations of the database data files and redo log files. |
|
|
See Also: Oracle9i Database Administrator’s Guide for more information on setting this initialization parameter value.
Using Rollback Segments
Rollback segments record the old values of data that are changed by each transaction, whether or not the transaction has been committed. Every database contains one or more rollback segments. Use rollback segments to provide read consistency, to roll back transactions, and to recover the database. The rollback segments of the starter database are as follows:
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Rollback segment SYSTEM is contained in tablespace SYS and is used by SYS.
Rollback segments _SYSSMU1$ through _SYSSMU10$ are a pool of rollback segments that any instance can use if it requires a rollback segment. They are contained in tablespace UNDOTBS<n> and are used by PUBLIC.
Using the Data Dictionary
The data dictionary is a protected collection of tables and views containing reference information on the database, its structure, and its users. The data that is stored in the dictionary includes the following:
