Oracle当前联机日志组损坏的处理

Oracle当前联机日志组损坏的处理一oracle日志的特性总结1oracle日志切换规律（从最大sequence#号切换到最小sequence#号）eg如下所示：下个当前日志组会是sequenc

Oracle当前联机日志组损坏的处理

一oracle 日志的特性总结

1 oracle 日志切换规律（从最大sequence#号切换到最小sequence#号）

eg 如下所示：下个当前日志组会是sequence#号为27的5号日志组

SQL> select group#,archived,sequence#,status from v$log;

GROUP# ARC SEQUENCE# STATUS

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

1 NO 32 CURRENT

2 YES 28 INACTIVE

3 YES 29 INACTIVE

4 YES 30 INACTIVE

5 YES 27 INACTIVE <------众日志组中sequence#号最小

6 YES 31 INACTIVE

6 rows selected.

SQL> alter system switch logfile ;

System altered.

SQL> select group#,archived,sequence#,status from v$log;

GROUP# ARC SEQUENCE# STATUS

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

1 YES 32 ACTIVE

2 YES 28 INACTIVE

3 YES 29 INACTIVE

4 YES 30 INACTIVE

5 NO 33 CURRENT

6 YES 31 INACTIVE

6 rows selected.

2 快速转换oracle日志组状态active为inactive

日志组切换后，香港虚拟主机，上一个当前日志组状态由current变成active，实际上是由于当前数据文件头部的scn值还位于状态为active日志组的low scn 和next scn 内，所以我们此刻如果立即发起alter sytem checkpoint 命令推进数据文件头部scn 变可使日志状态由active 变为inactive。

SQL> select group#,archived,sequence#,status from v$log;

GROUP# ARC SEQUENCE# STATUS

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

1 YES 32 INACTIVE

2 YES 34 INACTIVE

3 YES 35 INACTIVE

4 NO 36 CURRENT

5 YES 33 INACTIVE

6 YES 31 INACTIVE

SQL> alter system switch logfile;

System altered.

SQL> select group#,archived,sequence#,status from v$log;

GROUP# ARC SEQUENCE# STATUS

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

1 YES 32 INACTIVE

2 YES 34 INACTIVE

3 YES 35 INACTIVE

4 YES 36 ACTIVE <------sequence号为36的日志为active

5 YES 33 INACTIVE

6 NO 37 CURRENT

6 rows selected.

查询数据文件头部scn情况如下：

SQL> select hxfil,fhscn from x$kcvfh;

HXFIL FHSCN

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

1 2781239221

2 2781239221

3 2781239221

4 2781239221

5 2781239221

6 2781239221

7 2781239221

8 2781239221

11 2781239221

12 2781239221

13 2781239221

SQL> select sequence#,first_change#,next_change# from v$log_history;

SEQUENCE# FIRST_CHANGE# NEXT_CHANGE#

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

32 2781218249 2781218300

33 2781218300 2781219174

34 2781219174 2781219184

35 2781219184 2781239220

36 2781239220 2781239424

数据文件头部的scn：2781239221 处于sequence号为36的日志scn范围 内 2781239220 2781239424

SQL> alter system checkpoint;

System altered.

SQL> select hxfil,fhscn from x$kcvfh;

HXFIL FHSCN

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

1 2781239456

2 2781239456

3 2781239456

4 2781239456

5 2781239456

6 2781239456

7 2781239456

8 2781239456

11 2781239456

12 2781239456

13 2781239456

11 rows selected.

SQL> select group#,archived,sequence#,status from v$log;

GROUP# ARC SEQUENCE# STATUS

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

1 YES 32 INACTIVE

2 YES 34 INACTIVE

3 YES 35 INACTIVE

4 YES 36 INACTIVE

5 YES 33 INACTIVE

6 NO 37 CURRENT

3 clear 日志组的执行条件

clear的日志组状态不能是acitve 或者当前日志组

eg：

SQL> select group#,archived,sequence#,status from v$log;

GROUP# ARC SEQUENCE# STATUS

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

1 NO 38 CURRENT

2 YES 34 INACTIVE

3 YES 35 INACTIVE

4 YES 36 INACTIVE

5 YES 33 INACTIVE

6 YES 37 ACTIVE

SQL> alter database clear logfile group 6;

alter database clear logfile group 6

*

ERROR at line 1:

ORA-01624: log 6 needed for crash recovery of instance CRM (thread 1)

ORA-00312: online log 6 thread 1: '/oracle/CRM2/CRM/redo06.log'

ORA-00312: online log 6 thread 1: '/oracle/CRM2/CRM/redo06b.log'

二 数据库一直open当前联机日志组内成员全部损坏

此种情况最终就是日志不能切换，影响到数据库的应用时我们才可能发现。如下所示日志状态：

1 数据库日志状态如下：

SQL> select group#,archived,sequence#,status from v$log;

GROUP# ARC SEQUENCE# STATUS

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

1 NO 44 INACTIVE

2 NO 40 INACTIVE

3 NO 41 INACTIVE

4 NO 42 INACTIVE

5 NO 45 CURRENT

6 NO 43 INACTIVE

6 rows selected.