You have not configured Oracle Managed Files (OMF) in your database. You do not want to scan the entire
datafile every time an incremental backup is performed. You decide to enable the block change tracking
feature.
Which statement should you use to enable the block change tracking feature?
A.
ALTER DATABASE ENABLE BLOCK CHANGE TRACKING;
B.
ALTER SYSTEM ENABLE BLOCK CHANGE TRACKING USING FILE <path>;
C.
ALTER DATABASE ENABLE BLOCK CHANGE TRACKING USING FILE <path>;
D.
ALTER SYSTEM ENABLE BLOCK CHANGE TRACKING;
Explanation:
You should use the ALTER DATABASE ENABLE BLOCK CHANGE TRACKING USING FILE <path>; statement. If OMF is configured in your database, then you need not specify the name of the block change tracking file in the ALTER DATABASE statement. The file is automatically located in the directory specified by the DB_CREATE_FILE_DEST parameter. In this scenario, OMF is not configured. Therefore, you must specify the location of the block change tracking file in the statement. After you enable block change tracking, RMAN uses the block change tracking file to determine the blocks the blocks that have changed and should be backed up in an incremental backup. This improves the performance because RMAN does not have to scan the entire datafiles during backup. RMAN backs up only the changed blocks and skips the unchanged blocks.
The options stating that you should issue the ALTER SYSTEM ENABLE BLOCK CHANGE TRACKING; or the ALTER SYSTEM ENABLE BLOCK CHANGE TRACKING USING FILE <path>; statements are incorrect. Each of these statements will generate an error because the block change tracking feature is enabled at the database level, not at the system level.
The option stating that you should issue the ALTER DATABASE ENABLE BLOCK CHANGE TRACKING; statement is incorrect because OMF is not configured in the database. If OMF is not configured, then you must specify the location of the block change tracking file in the ALTER DATABASE ENABLE BLOCK CHANGE TRACKING; statement.