因为数据仓库上asm的磁盘空间不足，需要删除早期的归档日志，查看资料有以下两种方式：

delete archivelog until time 'sysdate-N';

delete archivelog all completed before 'sysdate-N';

这两个命令的差别在哪里呢？

使用list 命令来查看一下究竟...

RMAN> list archivelog until time 'sysdate-1';

using target database control file instead of recovery catalog

List of Archived Log Copies for database with db_unique_name YANGDB

=====================================================================

Key     Thrd Seq     S Low Time

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

459     1    463     A 08-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_463_762800109.log

460     1    464     A 08-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_464_762800109.log

461     1    465     A 08-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_465_762800109.log

462     1    466     A 08-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_466_762800109.log

463     1    467     A 09-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_467_762800109.log

464     1    468     A 09-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_468_762800109.log

465     1    469     A 10-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_469_762800109.log

466     1    470     A 11-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_470_762800109.log

467     1    471     A 11-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_471_762800109.log

468     1    472     A 12-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_472_762800109.log

469     1    473     A 13-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_473_762800109.log

470     1    474     A 13-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_474_762800109.log

471     1    475     A 14-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_475_762800109.log

472     1   476    A 15-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_476_762800109.log

归档日志的序列号码到476

RMAN> list archivelog all completed before 'sysdate-1';

List of Archived Log Copies for database with db_unique_name YANGDB

=====================================================================

Key     Thrd Seq     S Low Time

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

459     1    463     A 08-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_463_762800109.log

460     1    464     A 08-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_464_762800109.log

461     1    465     A 08-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_465_762800109.log

462     1    466     A 08-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_466_762800109.log

463     1    467     A 09-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_467_762800109.log

464     1    468     A 09-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_468_762800109.log

465     1    469     A 10-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_469_762800109.log

466     1    470     A 11-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_470_762800109.log

467     1    471     A 11-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_471_762800109.log

468     1    472     A 12-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_472_762800109.log

469     1    473     A 13-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_473_762800109.log

470     1    474     A 13-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_474_762800109.log

471     1   475    A 14-JAN-12 Name: /opt/oracle/yangdb_arch/yangdb_1_475_762800109.log

归档日志的序列号码到475

查看v$archived_log 视图从中获取 时间和序列号信息！

SYS@yangdb> select THREAD#,sequence#,FIRST_TIME,COMPLETION_TIME

2   from v$archived_log order by thread#,sequence#;

THREAD# SEQUENCE# FIRST_TIME      COMPLETION_TIME

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

1        470  2012-01-11 11:00:10  2012-01-11 22:08:23

1        471  2012-01-11 22:08:20  2012-01-12 17:00:10

1        472  2012-01-12 17:00:10  2012-01-13 02:00:28

1        473  2012-01-13 02:00:28  2012-01-13 22:09:56

1        474  2012-01-13 22:09:55  2012-01-14 22:01:02

14752012-01-14 22:01:022012-01-15 06:46:14==list archivelog all completed 以COMPLETION_TIME为基准

1476  2012-01-15 06:46:142012-01-30 14:10:18 ==list archivelog until 以FIRST_TIME 为基准 编号476的日志横跨15号和30号两天，以first_time的值来截取！

1        477  2012-01-30 14:10:15  2012-01-30 14:10:23

1        478  2012-01-30 14:10:22  2012-01-30 14:10:29

1        479  2012-01-30 14:10:28  2012-01-30 14:10:33

1        480  2012-01-30 14:10:32  2012-01-30 14:10:40

总结：

delete archivelog until time 'sysdate-N';

该命令删除日志时的时间基准是first_name

delete archivelog all completed before 'sysdate-N';

该命令删除日志时的时间基准是completion_time