3.Your database is in ARCHIVELOG mode. You have two online redo log groups, each of which contains

one redo member. When you attempt to start the database, you receive the following errors:

ORA-00313: open failed for members of log group 1 of thread 1

ORA-00312: online log 1 thread 1: 'D:\REDO01.LOG'

You discover that the online redo log file of the current redo group is corrupted.

Which statement should you use to resolve this issue?

A. ALTER DATABASE DROP LOGFILE GROUP 1;

B. ALTER DATABASE CLEAR LOGFILE GROUP 1;

C. ALTER DATABASE CLEAR UNARCHIVED LOGFILE GROUP 1;

D. ALTER DATABASE DROP LOGFILE MEMBER 'D:\REDO01.LOG';

Answer: C

答案解析：

Table 30-4 Recovering After the Loss of an Online Redo Log Group

[[email protected] ~]$ oerr ora 313

00313, 00000, "open failed for members of log group %s of thread %s"

// *Cause:  The online log cannot be opened. May not be able to find file.

// *Action: See accompanying errors and make log available.

[[email protected] ~]$ oerr ora 312

00312, 00000, "online log %s thread %s: '%s'"

// *Cause:  This message reports the filename for details of another message.

// *Action: Other messages will accompany this message. See the

//          associated messages for the appropriate action to take.

你的資料庫在歸檔記錄模式。你有兩個線上重做日誌組，其中每個都包含一個重做成員。當您嘗試啟動資料

庫時，您會收到以下錯誤：

ORA-00313：執行緒1日誌組1成員開啟失敗 

ORA-00312：聯機日誌1執行緒1：'D：\ REDO01.LOG

你發現當前的重做組聯機重做日誌檔案被損壞。你應該使用哪種說法來解決這個問題？

Clearing Inactive, Unarchived Redo

Clearing a not-yet-archived redo log allows it to be reused without archiving it. This action makes backups unusable if they were started before the last change in the log, unless the file was taken offline before the first change in the log. Hence, if you need the cleared log file for recovery of a backup, then you cannot recover that backup. Clearing a not-yet-archived-redo-log, prevents complete recovery from backups due to the missing log.

To clear an inactive, online redo log group that has not been archived:

1. If the database is shut down, then start a new instance and mount the database:

   SQL> STARTUP MOUNT

2. Clear the log using the UNARCHIVED keyword.

   For example, to clear log group 2, issue the following SQL statement:

   SQL> ALTER DATABASE CLEAR UNARCHIVED LOGFILE GROUP 2;