Oracle Database Components
1. Datafiles
Datafiles are the physical files on disk where the actual data of the Oracle database is stored. Each tablespace in the database has one or more datafiles associated with it. These files are managed by the Oracle Database Management System (DBMS) and are crucial for data persistence.
Example: If you have a table named "Employees" in a tablespace called "USERS," the data for this table will be stored in one or more datafiles associated with the "USERS" tablespace.
2. Control Files
Control files are critical components that store metadata about the database, including the database name, creation time, and the locations of the datafiles and redo logs. The control files are essential for the database to function correctly and are used during recovery operations.
Example: If the database crashes, the control file is used to identify the state of the database before the crash and to guide the recovery process.
3. Redo Logs
Redo logs, also known as redo log files, are used to record all changes made to the database. These logs are crucial for database recovery because they allow the database to replay transactions and restore the database to a consistent state after a failure.
Example: If a power outage occurs while a transaction is being processed, the redo logs will contain the information needed to complete the transaction once the database is restarted.