052-240(新增70题2018)

You are using the following command to clear the log file group:
ALTER DATABASE CLEAR LOGFILE GROUP 2;
In which case would the command be successful?
A. Group 2 is the active group.
B. Group 2 is the current group.
C. Database is in the MOUNT state.
D. Group 2 has been already archived.
Answer: D
Clearing a Redo Log File

A redo log file might become corrupted while the database is open, and ultimately stop database activity because archiving cannot continue. In this situation the ALTER DATABASE CLEAR LOGFILE statement can be used to reinitialize the file without shutting down the database.

The following statement clears the log files in redo log group number 3:

ALTER DATABASE CLEAR LOGFILE GROUP 3;

This statement overcomes two situations where dropping redo logs is not possible:

• If there are only two log groups

• The corrupt redo log file belongs to the current group

If the corrupt redo log file has not been archived, use the UNARCHIVED keyword in the statement.

ALTER DATABASE CLEAR UNARCHIVED LOGFILE GROUP 3;

This statement clears the corrupted redo logs and avoids archiving them. The cleared redo logs are available for use even though they were not archived.