|
Explain what are Oracle Catalog and Oracle Archive log?Oracle Catalog:
- Oracle catalog contains tables and views to get information about the database. It helps user to understand the available tables, attributes, constraints etc.
- Updates the recovery catalog with RMAN metadata in the current control file (default) or a control file copy.
Oracle Archivelog:
- Oracle Archive log mode of a database in Oracle, ensures, the online redo logs are not overwritten before they are archived. This ensures that recovery is possible.
- When a database runs in ARCHIVELOG mode the archiving of the redo log is enabled.
- The database control file indicates that a group of filled redo log files cannot be reused by LGWR until the group is archived.
- A filled group becomes available for archiving immediately after a redo log switch occurs.
The archiving of filled groups has these advantages:
1. A database backup, together with online and archived redo log files, guarantees that you can recover all committed transactions in the event of an operating system or disk failure.
2. An archived log is kept to use as a backup taken while the database is open and in normal system use.
3. A standby database can be kept current with its original database by continuously applying the original archived redo logs to the standby.
|
