_ Disable_logging how to disable log generation

In our actual work, in non-archive mode (Note: The Archive mode will cause log corruption), use _ disable_logging to disable log generation, under this condition, the performance of some special operations (such as batch loading or Benchmark Testing) can be greatly improved.

Example of completion prohibition:

First, we need to start two sessions, one for management and the other for testing.

1. Session 1: Use the Sys user to connect to the database. Currently, _ disable_logging is not set and the database is in normal state.

$ sqlplus "/ as sysdba" SQL*Plus: Release 9.2.0.4.0 - Production on Fri Apr 14 09:30:42 2006 Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved. Connected to: Oracle9i Enterprise Edition Release 9.2.0.4.0 - 64bit Production With the Partitioning option JServer Release 9.2.0.4.0 - Production SQL> col member for a40 SQL> select * from v$logfile; GROUP# STATUS TYPE MEMBER ---------- ------- ------- 1 ONLINE /opt/oracle9/oradata/testora9/redo01.log 2 ONLINE /opt/oracle9/oradata/testora9/redo02.log 3 ONLINE /opt/oracle9/oradata/testora9/redo03.log SQL> alter system switch logfile; System altered. SQL> select * from v$log; GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS FIRST_CHANGE# FIRST_TIM ---------- ---------- ---------- ---------- 1 1 148 104857600 1 NO CURRENT 262708457 14-APR-06 2 1 146 104857600 1 NO INACTIVE 262662667 14-APR-06 3 1 147 104857600 1 NO ACTIVE 262675537 14-APR-06

2. Session 2 is connected through the Scott user and the following update is executed:

SQL> connect scott/tiger Connected. SQL> update emp set sal=3000 where empno=7788; 1 row updated. SQL> commit; Commit complete.

3. Dump redo logs in the session

SQL> ALTER SYSTEM DUMP LOGFILE ' /opt/oracle9/oradata/testora9/redo01.log'; System altered.

4. Observe the trace file and record the redo information in normal state.

The TRC file is too large to be pasted.

5. Disable log generation and switch logs

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. Update Scott again.

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. Dump logs

SQL> ALTER SYSTEM DUMP LOGFILE ' /opt/oracle9/oradata/testora9/redo02.log'; System altered.

8. Record the redo information at this time

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

No redo is generated. Currently, the database only records a small amount of necessary information.