1.在线添加日志组成员
SQL> alter database drop logfile member ‘/u01/app/oracle/oradata/orcl/redo01a.log‘;
Database altered.
SQL> alter database add logfile member ‘/u01/app/oracle/fast_recovery_area/orcl/redo01a.log‘ to group 1;
Database altered.
SQL> alter database add logfile member ‘/u01/app/oracle/fast_recovery_area/orcl/redo02a.log‘ to group 2;
Database altered.
SQL> alter database add logfile member ‘/u01/app/oracle/fast_recovery_area/orcl/redo03a.log‘ to group 3;
Database altered.
SQL> alter database add logfile group 4 (‘/u01/app/oracle/oradata/orcl/redo04.log‘,‘/u01/app/oracle/fast_recovery_area/orcl/redo04a.log‘) size 100m;
Database altered.
SQL> alter database add logfile group 5 (‘/u01/app/oracle/oradata/orcl/redo05.log‘,‘/u01/app/oracle/fast_recovery_area/orcl/redo05a.log‘) size 100m;
Database altered.
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我们在切换日志的时候，oracle会去找下一个状态为INACTIVE的日志组：
<pre code_snippet_id="1717292" snippet_file_name="blog_20160615_2_9483808" name="code" class="sql">SQL> alter system switch logfile;
System altered.
SQL> select * from v$log;
GROUP# THREAD# SEQUENCE# BYTES BLOCKSIZE MEMBERS ARC STATUS FIRST_CHANGE# FIRST_TIM NEXT_CHANGE# NEXT_TIME
---------- ---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- --------- ------------ ---------
1 1 13 104857600 512 2 NO INACTIVE 394447 15-JUN-16 403542 15-JUN-16
2 1 14 104857600 512 2 NO ACTIVE 403542 15-JUN-16 403931 15-JUN-16
3 1 17 104857600 512 2 NO CURRENT 403940 15-JUN-16 2.8147E+14
4 1 15 104857600 512 2 NO ACTIVE 403931 15-JUN-16 403934 15-JUN-16
5 1 16 104857600 512 2 NO ACTIVE 403934 15-JUN-16 403940 15-JUN-16
SQL> alter system switch logfile;
System altered.
SQL> select * from v$log;
GROUP# THREAD# SEQUENCE# BYTES BLOCKSIZE MEMBERS ARC STATUS FIRST_CHANGE# FIRST_TIM NEXT_CHANGE# NEXT_TIME
---------- ---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- --------- ------------ ---------
1 1 18 104857600 512 2 NO CURRENT 403948 15-JUN-16 2.8147E+14
2 1 14 104857600 512 2 NO ACTIVE 403542 15-JUN-16 403931 15-JUN-16
3 1 17 104857600 512 2 NO ACTIVE 403940 15-JUN-16 403948 15-JUN-16
4 1 15 104857600 512 2 NO ACTIVE 403931 15-JUN-16 403934 15-JUN-16
5 1 16 104857600 512 2 NO ACTIVE 403934 15-JUN-16 403940 15-JUN-16
SQL> alter system switch logfile;
System altered.
SQL> select * from v$log;
GROUP# THREAD# SEQUENCE# BYTES BLOCKSIZE MEMBERS ARC STATUS FIRST_CHANGE# FIRST_TIM NEXT_CHANGE# NEXT_TIME
---------- ---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- --------- ------------ ---------
1 1 18 104857600 512 2 NO ACTIVE 403948 15-JUN-16 403958 15-JUN-16
2 1 19 104857600 512 2 NO CURRENT 403958 15-JUN-16 2.8147E+14
3 1 17 104857600 512 2 NO ACTIVE 403940 15-JUN-16 403948 15-JUN-16
4 1 15 104857600 512 2 NO INACTIVE 403931 15-JUN-16 403934 15-JUN-16
5 1 16 104857600 512 2 NO INACTIVE 403934 15-JUN-16 403940 15-JUN-16
SQL> alter system switch logfile;
System altered.
SQL> select * from v$log;
GROUP# THREAD# SEQUENCE# BYTES BLOCKSIZE MEMBERS ARC STATUS FIRST_CHANGE# FIRST_TIM NEXT_CHANGE# NEXT_TIME
---------- ---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- --------- ------------ ---------
1 1 18 104857600 512 2 NO ACTIVE 403948 15-JUN-16 403958 15-JUN-16
2 1 19 104857600 512 2 NO ACTIVE 403958 15-JUN-16 403962 15-JUN-16
3 1 17 104857600 512 2 NO ACTIVE 403940 15-JUN-16 403948 15-JUN-16
4 1 20 104857600 512 2 NO CURRENT 403962 15-JUN-16 2.8147E+14
5 1 16 104857600 512 2 NO INACTIVE 403934 15-JUN-16 403940 15-JUN-16
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2.删除在线日志组和日志组成员
删除日志组成员，如果发现不能删除，应该是状态CURRENT，只要切换日志组就好了。
SQL> alter database drop logfile member ‘/u01/app/oracle/oradata/orcl/redo01a.log‘;
alter database drop logfile member ‘/u01/app/oracle/oradata/orcl/redo01a.log‘
*
ERROR at line 1:
ORA-01609: log 1 is the current log for thread 1 - cannot drop members
ORA-00312: online log 1 thread 1: ‘/u01/app/oracle/oradata/orcl/redo01.log‘
ORA-00312: online log 1 thread 1: ‘/u01/app/oracle/oradata/orcl/redo01a.log‘
SQL> alter system switch logfile;
System altered.
SQL> alter database drop logfile member ‘/u01/app/oracle/oradata/orcl/redo01a.log‘;
Database altered.
删除日志组；
ALTER DATABASE DROP LOGFILE GROUP N;--这里的N就是你的日志组编号，如果不能删除，就和上面一样切换日志组。
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原文链接：https://blog.csdn.net/cscscscsc/article/details/51679023