052-240(新增70题2018)-优快云博客

本文介绍在Oracle数据库中使用ALTER DATABASE CLEAR LOGFILE命令清除日志文件组的场景，尤其当红olog文件损坏且未归档时，此命令可在不停止数据库活动的情况下重新初始化文件。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

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If the corrupt redo log file has not been archived, use the UNARCHIVED keyword in the statement.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

转载于:https://www.cnblogs.com/Babylon/p/8623696.html