--#日志组的添加
--查看日志组个数、成员、大小
SQL> select group#,members,bytes/1024/1024 m ,status from v$log;

    GROUP#    MEMBERS          M STATUS
---------- ---------- ---------- ----------------
         1          1         50 CURRENT
         2          1         50 INACTIVE
         3          1         50 INACTIVE

SQL>
SQL> select group#,member from v$logfile;

    GROUP# MEMBER
---------- --------------------------------------------------
         3 /u01/app/oracle/oradata/ORA/redo03.log
         2 /u01/app/oracle/oradata/ORA/redo02.log
         1 /u01/app/oracle/oradata/ORA/redo01.log

SQL>
--添加一组日志文件
SQL> alter database add logfile group 4 ('/u01/app/oracle/oradata/ORA/redo04.log') size 50m;

Database altered.

SQL>
SQL> select group#,member from v$logfile;

    GROUP# MEMBER
---------- --------------------------------------------------
         3 /u01/app/oracle/oradata/ORA/redo03.log
         2 /u01/app/oracle/oradata/ORA/redo02.log
         1 /u01/app/oracle/oradata/ORA/redo01.log
         4 /u01/app/oracle/oradata/ORA/redo04.log

SQL>
SQL> select group#,members,bytes/1024/1024 m ,status from v$log;

    GROUP#    MEMBERS          M STATUS
---------- ---------- ---------- ----------------
         1          1         50 CURRENT
         2          1         50 INACTIVE
         3          1         50 INACTIVE
         4          1         50 UNUSED

SQL>
--需要手工切换下日志
SQL> alter system switch logfile;
\
System altered.
---再查看下状态
SQL> select group#,members,bytes/1024/1024 m ,status from v$log;

    GROUP#    MEMBERS          M STATUS
---------- ---------- ---------- ----------------
         1          1         50 ACTIVE
         2          1         50 INACTIVE
         3          1         50 INACTIVE
         4          1         50 CURRENT

SQL>
--增加的日志组的成员
SQL> alter database add logfile member '/u01/app/oracle/disk/redo01b.log' to group 1;

Database altered.

SQL>
--再次查看
SQL> select group#,member from v$logfile;

    GROUP#
----------
MEMBER
--------------------------------------------------------------------------------
         3
/u01/app/oracle/oradata/ORA/redo03.log

         2
/u01/app/oracle/oradata/ORA/redo02.log

         1
/u01/app/oracle/oradata/ORA/redo01.log

    GROUP#
----------
MEMBER
--------------------------------------------------------------------------------
         4
/u01/app/oracle/oradata/ORA/redo04.log

         1
/u01/app/oracle/disk/redo01b.log

SQL>
----删除一个日志组

SQL> select GROUP#,bytes/1024/1024,MEMBERS,STATUS from v$log;

    GROUP# BYTES/1024/1024    MEMBERS STATUS
---------- --------------- ---------- ----------------
         1              50          2 INACTIVE
         2              50          1 INACTIVE
         3              50          1 INACTIVE
         4              50          1 CURRENT

SQL> ALTER DATABASE DROP LOGFILE GROUP 3;

Database altered.

SQL> select GROUP#,bytes/1024/1024,MEMBERS,STATUS from v$log;

    GROUP# BYTES/1024/1024    MEMBERS STATUS
---------- --------------- ---------- ----------------
         1              50          2 INACTIVE
         2              50          1 INACTIVE
         4              50          1 CURRENT

SQL>

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日志组的管理

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