使用_disable_logging即可禁止日志的生成 （2）

   来源：赛迪网    作者：Daniel

5.禁用日志生成的,并且切换日志

SQL> alter system set "_disable_logging"=true;

System altered.

SQL> alter system switch logfile;

System altered.

SQL> select * from v$log;

GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS FIRST_CHANGE# FIRST_TIM

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

1 1 148 104857600 1 NO ACTIVE 262708457 14-APR-06

2 1 149 104857600 1 NO CURRENT 262708606 14-APR-06

3 1 147 104857600 1 NO INACTIVE 262675537 14-APR-06

6.SCOTT用户再更新

SQL> show parameter disable

NAME TYPE VALUE

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

_disable_logging boolean TRUE

SQL> update emp set sal=4000 where empno=7788;

1 row updated.

SQL> commit;

Commit complete.

7.转储日志

SQL> ALTER SYSTEM DUMP LOGFILE '

/opt/oracle9/oradata/testora9/redo02.log';

System altered.

8.记录此时REDO信息

DUMP OF REDO FROM FILE '/opt/oracle9/oradata/testora9/redo02.log'

Opcodes *.*

DBA's: (file # 0, block # 0) thru (file # 65534, block # 4194303)

RBA's: 0x000000.00000000.0000 thru 0xffffffff.ffffffff.ffff

SCN's scn: 0x0000.00000000 thru scn: 0xffff.ffffffff

Times: creation thru eternity

FILE HEADER:

Software vsn=153092096=0x9200000, Compatibility Vsn=153092096=0x9200000

Db ID=1628068176=0x610a5950, Db Name='TESTORA9'

Activation ID=1628067152=0x610a5550

Control Seq=1163=0x48b, File size=204800=0x32000

File Number=2, Blksiz=512, File Type=2 LOG

descrip:"Thread 0001, Seq# 0000000149, SCN 0x00000fa89d7e-0xffffffffffff"

thread: 1 nab: 0xffffffff seq: 0x00000095 hws: 0x1 eot: 1 dis: 0

reset logs count: 0x1f435110 scn: 0x0000.00000001

Low scn: 0x0000.0fa89d7e 04/14/2006 09:33:43

Next scn: 0xffff.ffffffff 01/01/1988 00:00:00

Enabled scn: 0x0000.00000001 04/26/2004 15:56:10

Thread closed scn: 0x0000.0fa89d7e 04/14/2006 09:33:43

Log format vsn: 0x8000000 Disk cksum: 0xcac7 Calc cksum: 0xcac7

Terminal Recovery Stamp scn: 0x0000.00000000 01/01/1988 00:00:00

Most recent redo scn: 0x0000.00000000

Largest LWN: 0 blocks

End-of-redo stream : No

Unprotected mode

Miscellaneous flags: 0x0

END OF REDO DUMP

至此已经没有REDO的生成.数据库目前仅仅记录少量的必要信息。