redo文件管理

1. 查看數據庫版本

SQL> select * from v$version;

BANNER

--------------------------------------------------------------------------------

Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production

PL/SQL Release 11.2.0.1.0 - Production

CORE	11.2.0.1.0	Production

TNS for Linux: Version 11.2.0.1.0 - Production

NLSRTL Version 11.2.0.1.0 - Production

2. 查看重做日誌文件

SQL> select * from v$logfile;

GROUP# STATUS TYPE MEMBER IS_

---------- ------- ------- -------------------------------------------------- ---

3 ONLINE /home/oracle/app/oracle/oradata/orcl/redo03.log NO

2 ONLINE /home/oracle/app/oracle/oradata/orcl/redo02.log NO

1 ONLINE /home/oracle/app/oracle/oradata/orcl/redo01.log NO

3. 查看重做日誌組信息

SQL> select group#,bytes,members from v$log;

    GROUP#	BYTES	 MEMBERS

---------- ---------- ----------

	 1   52428800	       1

	 2   52428800	       1

	 3   52428800	       1

4. 查看重做日誌和重做日誌組狀態

SQL> select a.group#,a.member,b.status,b.bytes

from v$logfile a,v$log b

where a.group#=b.group#;

GROUP# MEMBER STATUS BYTES

---------- -------------------------------------------------- ---------------- ----------

3 /home/oracle/app/oracle/oradata/orcl/redo03.log CURRENT 52428800

2 /home/oracle/app/oracle/oradata/orcl/redo02.log INACTIVE 52428800

1 /home/oracle/app/oracle/oradata/orcl/redo01.log INACTIVE 52428800

4. 添加重做日誌組

每個重做日誌組可以添加一個或者多個重做日誌文件

語法：

alter database add logfile group 組序號('文件名1','文件名2',......'文件n'） size 文件大小;

SQL> alter database add logfile group 4('/home/oracle/app/oracle/oradata/orcl/redo04_01.log',

'/home/oracle/app/oracle/oradata/orcl/redo04_02.log') size 100M;

SQL> select a.group#,a.member,b.bytes/1024/1024 "M",b.status

from v$logfile a,v$log b

where a.group#=b.group#;

GROUP# MEMBER M STATUS

---------- -------------------------------------------------- ---------- ----------------

3 /home/oracle/app/oracle/oradata/orcl/redo03.log 50 CURRENT

2 /home/oracle/app/oracle/oradata/orcl/redo02.log 50 INACTIVE

1 /home/oracle/app/oracle/oradata/orcl/redo01.log 50 INACTIVE

4 /home/oracle/app/oracle/oradata/orcl/redo04_01.log 100 UNUSED

4 /home/oracle/app/oracle/oradata/orcl/redo04_02.log 100 UNUSED

綠色標記：剛創建的重做日誌文件名稱，大小，狀態。其中文件名爲redo04_01.log和red04_02.log，文件大小100M，

狀態unused（因爲剛創建，重做日誌文件從未被使用）

知識擴展：redo四種狀態

current：當前活動重做日誌，進行實例恢復是必須的！

active：活動的非當前重做日誌，實例恢復時會被用到。此狀態意味checkpoint尚未完成.

inactive：非活動日誌，在實例恢復時不需要，但介質恢復時需要。

unused：日誌從未被寫入，可能剛被添加或者resetlogs後被重置

5.添加重做日誌文件

添加重置日誌文件，不需要指定文件大小，新創建的重做日誌文件大小與已經存在的重做日誌大小一致

語法：

alter database add logfile member '文件名' to group 組序號

SQL> alter database add logfile member '/home/oracle/app/oracle/oradata/orcl/redo04_04.log' to group 4;

SQL> select a.group#,a.member,b.bytes/1024/1024,b.status

    from v$logfile a,v$log b

       where a.group#=b.group#;

    GROUP# MEMBER					      B.BYTES/1024/1024 STATUS

---------- -------------------------------------------------- ----------------- ----------------

	 3 /home/oracle/app/oracle/oradata/orcl/redo03.log		     50 CURRENT

	 2 /home/oracle/app/oracle/oradata/orcl/redo02.log		     50 INACTIVE

	 1 /home/oracle/app/oracle/oradata/orcl/redo01.log		     50 INACTIVE

	 4 /home/oracle/app/oracle/oradata/orcl/redo04_01.log		    100 UNUSED

	 4 /home/oracle/app/oracle/oradata/orcl/redo04_02.log		    100 UNUSED

	 4 /home/oracle/app/oracle/oradata/orcl/redo04_04.log		    100 UNUSED

5.刪除重做日誌文件

重做日誌文件狀態是current和active是不能被刪除
不能刪除組內唯一成員
重做日誌文件被刪除，物理文件是沒有被刪除，需要手動去刪除物理文件
如果想刪除當前處於current或者active狀態的重做日誌文件，必須要把當前的重做日誌文件切換到inactive狀態

如果刪除重做日誌文件，儘量被刪除重做日誌處於歸檔狀態。（查看是否是歸檔狀態v$log視圖中的archived字段）

語法：

alter database drop logfile member '文件名'

不能刪除組內唯一成員

SQL> select a.group#,a.member,b.bytes,b.status,b.archived

from v$logfile a, v$log b

where a.group#=b.group#;

GROUP# MEMBER BYTES STATUS ARC

---------- -------------------------------------------------- ---------- ---------------- ---

3 /home/oracle/app/oracle/oradata/orcl/redo03.log 52428800 INACTIVE YES

2 /home/oracle/app/oracle/oradata/orcl/redo02.log 52428800 INACTIVE YES

1 /home/oracle/app/oracle/oradata/orcl/redo01.log 52428800 CURRENT NO

4 /home/oracle/app/oracle/oradata/orcl/redo04_01.log 104857600 INACTIVE YES

4 /home/oracle/app/oracle/oradata/orcl/redo04_02.log 104857600 INACTIVE YES

4 /home/oracle/app/oracle/oradata/orcl/redo04_04.log 104857600 INACTIVE YES

刪除重做日誌狀態爲current，會提示錯誤信息

SQL> alter database drop logfile member '/home/oracle/app/oracle/oradata/orcl/redo03.log';

alter database drop logfile member '/home/oracle/app/oracle/oradata/orcl/redo03.log'

ERROR at line 1:

ORA-00361: cannot remove last log member /home/oracle/app/oracle/oradata/orcl/redo03.log for group 3

如果想刪除當前處於current或者active狀態的重做日誌文件，必須要把當前的重做日誌文件切換到inactive狀態

SQL> alter system switch logfile;

System altered.

SQL> select a.group#,a.member,b.bytes/1024/1024,b.status,b.archived

2 from v$logfile a,v$log b

3 where a.group#=b.group#;

GROUP# MEMBER BYTES STATUS ARC

---------- -------------------------------------------------- ---------- ---------------- ---

3 /home/oracle/app/oracle/oradata/orcl/redo03.log 52428800 ACTIVE YES

2 /home/oracle/app/oracle/oradata/orcl/redo02.log 52428800 INACTIVE YES

1 /home/oracle/app/oracle/oradata/orcl/redo01.log 52428800 INACTIVE YES

4 /home/oracle/app/oracle/oradata/orcl/redo04_01.log 104857600 CURRENT NO

4 /home/oracle/app/oracle/oradata/orcl/redo04_02.log 104857600 CURRENT NO

4 /home/oracle/app/oracle/oradata/orcl/redo04_04.log 104857600 CURRENT NO

如果刪除重做日誌處於current或者active狀態，會報 the current log for thread 1 - cannot drop members

SQL> alter database drop logfile member '/home/oracle/app/oracle/oradata/orcl/redo04_01.log';

alter database drop logfile member '/home/oracle/app/oracle/oradata/orcl/redo04_01.log'

ERROR at line 1:

ORA-01609: log 4 is the current log for thread 1 - cannot drop members

ORA-00312: online log 4 thread 1: '/home/oracle/app/oracle/oradata/orcl/redo04_01.log'

ORA-00312: online log 4 thread 1: '/home/oracle/app/oracle/oradata/orcl/redo04_02.log'

ORA-00312: online log 4 thread 1: '/home/oracle/app/oracle/oradata/orcl/redo04_04.log'

重做日誌文件被刪除，物理文件是沒有被刪除，需要手動去刪除物理文件

SQL> alter system switch logfile;

System altered.

SQL> select a.group#,a.member,b.bytes/1024/1024 "M", b.status,b.archived

from v$logfile a,v$log b

where a.group#=b.group#;

GROUP# MEMBER M STATUS ARC

---------- -------------------------------------------------- ---------- ---------------- ---

3 /home/oracle/app/oracle/oradata/orcl/redo03.log 50 INACTIVE YES

2 /home/oracle/app/oracle/oradata/orcl/redo02.log 50 CURRENT NO

1 /home/oracle/app/oracle/oradata/orcl/redo01.log 50 INACTIVE YES

4 /home/oracle/app/oracle/oradata/orcl/redo04_01.log 100 INACTIVE YES

4 /home/oracle/app/oracle/oradata/orcl/redo04_02.log 100 INACTIVE YES

4 /home/oracle/app/oracle/oradata/orcl/redo04_04.log 100 INACTIVE YES

SQL> alter database drop logfile member '/home/oracle/app/oracle/oradata/orcl/redo04_01.log';

Database altered.

[oracle@localhost orcl]$ ls -ls|grep redo

51260 -rw-r----- 1 oracle oinstall 52429312 12-10 14:16 redo01.log

51260 -rw-r----- 1 oracle oinstall 52429312 12-10 14:19 redo02.log

51260 -rw-r----- 1 oracle oinstall 52429312 12-10 14:11 redo03.log

102508 -rw-r----- 1 oracle oinstall 104858112 12-10 14:16 redo04_01.log

102508 -rw-r----- 1 oracle oinstall 104858112 12-10 14:16 redo04_02.log

102508 -rw-r----- 1 oracle oinstall 104858112 12-10 13:29 redo04_03.log

102508 -rw-r----- 1 oracle oinstall 104858112 12-10 14:16 redo04_04.log

需要手動刪除物理文件哦！

rm -rf /home/oracle/app/oracle/oradata/orcl/redo04_01.log

6.刪除重做日誌組

一個實例必須要兩組重做日誌，如果重做日誌組只有兩組，不能被刪除

刪除重做日誌組，需要手動刪除物理文件（非OMF）

重做日誌組內有重做日誌文件處於current或者active狀態，不能刪除重做日誌組

如果重做日誌組內重做日誌文件有null狀態和inavtive狀態並存，只能刪除重做日誌文件狀態是inactive文件

語法：

alter database drop logfile group 組序號

重做日誌組內有重做日誌文件處於current或者active狀態，不能刪除重做日誌組

SQL> select a.group#,a.member,b.bytes/1024/1024 "M", b.status,b.archived

from v$logfile a,v$log b

where a.group#=b.group#;

GROUP# MEMBER M STATUS ARC

---------- -------------------------------------------------- ---------- ---------------- ---

3 /home/oracle/app/oracle/oradata/orcl/redo03.log 50 INACTIVE YES

2 /home/oracle/app/oracle/oradata/orcl/redo02.log 50 CURRENT NO

1 /home/oracle/app/oracle/oradata/orcl/redo01.log 50 INACTIVE YES

4 /home/oracle/app/oracle/oradata/orcl/redo04_02.log 100 INACTIVE YES

4 /home/oracle/app/oracle/oradata/orcl/redo04_04.log 100 INACTIVE YES

SQL> alter database drop logfile group 2;

alter database drop logfile group 2

ERROR at line 1:

ORA-01623: log 2 is current log for instance orcl (thread 1) - cannot drop

ORA-00312: online log 2 thread 1: '/home/oracle/app/oracle/oradata/orcl/redo02.log'

刪除重做日誌組，需要手動刪除物理文件（非OMF）

SQL> select a.group#,a.member,b.bytes/1024/1024 "M", b.status,b.archived

from v$logfile a,v$log b

where a.group#=b.group#;

GROUP# MEMBER M STATUS ARC

---------- -------------------------------------------------- ---------- ---------------- ---

3 /home/oracle/app/oracle/oradata/orcl/redo03.log 50 INACTIVE YES

2 /home/oracle/app/oracle/oradata/orcl/redo02.log 50 CURRENT NO

1 /home/oracle/app/oracle/oradata/orcl/redo01.log 50 INACTIVE YES

4 /home/oracle/app/oracle/oradata/orcl/redo04_02.log 100 INACTIVE YES

4 /home/oracle/app/oracle/oradata/orcl/redo04_04.log 100 INACTIVE YES

SQL> alter database drop logfile group 4 ;

Database altered.

需要手動刪除物理文件哦

[oracle@localhost orcl]$ ls -ls|grep redo

51260 -rw-r----- 1 oracle oinstall 52429312 12-10 14:16 redo01.log

51260 -rw-r----- 1 oracle oinstall 52429312 12-10 14:32 redo02.log

51260 -rw-r----- 1 oracle oinstall 52429312 12-10 14:11 redo03.log

102508 -rw-r----- 1 oracle oinstall 104858112 12-10 14:16 redo04_02.log

102508 -rw-r----- 1 oracle oinstall 104858112 12-10 14:16 redo04_04.log

一個實例必須要兩組重做日誌

SQL> select a.group#,a.member,b.bytes/1024/1024 "M", b.status,b.archived

from v$logfile a,v$log b

where a.group#=b.group#;

GROUP# MEMBER M STATUS ARC

---------- -------------------------------------------------- ---------- ---------------- ---

3 /home/oracle/app/oracle/oradata/orcl/redo03.log 50 INACTIVE YES

2 /home/oracle/app/oracle/oradata/orcl/redo02.log 50 CURRENT NO

一個實例必須要有兩組重做日組，如果刪除其中組就會報would leave less than 2 log files for instance orcl (thread 1)

SQL> alter database drop logfile group 3 ;

alter database drop logfile group 3

ERROR at line 1:

ORA-01567: dropping log 3 would leave less than 2 log files for instance orcl (thread 1)

ORA-00312: online log 3 thread 1: '/home/oracle/app/oracle/oradata/orcl/redo03.log'

6.清空重做日誌組

清空重做日誌：對重做日誌文件內容全部初始化，相當於刪除重做日誌文件，並重新創建重做日誌文件一個實例必須要兩組重做日誌，如果重做日誌組只有兩組，不能被被清空

重做日誌組內有重做日誌文件處於current或者active狀態，不能清空重做日誌組

SQL> select a.group#,a.member,b.bytes/1024/1024,b.status,b.archived

from v$logfile a,v$log b

where a.group#=b.group#;

GROUP# MEMBER B.BYTES/1024/1024 STATUS ARC

---------- -------------------------------------------------- ----------------- ---------------- ---

3 /home/oracle/app/oracle/oradata/orcl/redo03.log 50 INACTIVE YES

2 /home/oracle/app/oracle/oradata/orcl/redo02.log 50 CURRENT NO

5 /home/oracle/app/oracle/oradata/orcl/redo05_01.log 100 UNUSED YES

6 /home/oracle/app/oracle/oradata/orcl/redo06_01.log 100 INACTIVE NO

清空重做日誌組：

SQL> alter database clear logfile group 3;

清空重做日誌文件

SQL> alter database clear logfile '/home/oracle/app/oracle/oradata/orcl/redo05_01.log';

如果重做日誌處於未歸檔狀態，必須使用unarchived 進行清空

SQL> alter database clear unarchived logfile group 6;

Database altered.

6.與重做日誌有關的動態視圖

v$log

v$logfile

v$log_history

v$log視圖中重要的字段

Status of the log member:

UNUSED - Online redo log has never been written to. This is the state of a redo log that was just added, or just after a RESETLOGS, when it is not the current redo log.
CURRENT - Current redo log. This implies that the redo log is active. The redo log could be open or closed.
ACTIVE - Log is active but is not the current log. It is needed for crash recovery. It may be in use for block recovery. It may or may not be archived.
CLEARING - Log is being re-created as an empty log after an ALTER DATABASE CLEAR LOGFILE statement. After the log is cleared, the status changes to UNUSED.
CLEARING_CURRENT - Current log is being cleared of a closed thread. The log can stay in this status if there is some failure in the switch such as an I/O error writing the new log header.
INACTIVE - Log is no longer needed for instance recovery. It may be in use for media recovery. It may or may not be archived.

v$logfile視圖中重要的字段：Status of the log member:

INVALID - File is inaccessible
STALE - File's contents are incomplete
DELETED - File is no longer used
null - File is in use

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