In Oracle, control file is used for database recovery. The control file is also used to identify the database and redo log files that must be opened for database operation to go ahead, whenever an instance of an ORACLE database begins.
The control file in Oracle plays a crucial role in the functioning of the database. Here are its primary usages:
- Record Keeping: The control file maintains metadata about the physical structure of the database. This includes information about data files, redo log files, and the database itself. It keeps track of the database name, data files, redo log files, time stamps, and checkpoints.
- Database Recovery: The control file is essential for database recovery operations. In the event of a failure, the control file is consulted to determine the exact status of the database before the failure. This information is crucial for recovery processes to bring the database back to a consistent state.
- Opening and Closing the Database: During the startup of the Oracle database, the control file is read to ensure the consistency and integrity of the database. It contains information needed to open the database. Similarly, during a clean shutdown, the control file is updated to reflect the database’s closed status.
- Renaming Datafiles and Redo Log Files: The control file is involved when renaming or relocating data files and redo log files. It keeps track of the physical names and locations of these files.
- Archiving Redo Log Files: The control file is used to determine which redo log files need to be archived. It keeps track of the status of the redo log groups and helps in managing the archiving process.
In summary, the control file in Oracle serves as a critical component for maintaining database integrity, assisting in recovery operations, and facilitating various administrative tasks related to the database structure and files.