_disable_logging对于性能的影响

王朝other·作者佚名  2008-05-31
窄屏简体版  字體: |||超大  

设置了_disable_logging参数,可以禁用日志的生成,从而提高某些测试的性能.

以下测试,纯属测试目的,其他内容请参考本站其他文章:

http://www.eygle.com/archives/2006/04/more_about_disable_logging.Html

禁用日志情况下:

SQL> connect / as sysdba

Connected.

SQL> shutdown immediate;

Database closed.

Database dismounted.

Oracle instance shut down.

SQL> startup

ORACLE instance started.

Total System Global Area 286755168 bytes

Fixed Size 731488 bytes

Variable Size 167772160 bytes

Database Buffers 117440512 bytes

Redo Buffers 811008 bytes

Database mounted.

Database opened.

SQL> connect eygle/eygle

Connected.

SQL> show parameter disable

NAME TYPE VALUE

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

_disable_logging boolean TRUE

测试创建100万数据表:

SQL> create table test as select * from dba_objects where 1=0;

Table created.

SQL> set timing on

SQL> begin

2 for i in 1 .. 10000 loop

3 insert into test select * from dba_objects where rownum < 101;

4 commit;

5 end loop;

6 end;

7 /

PL/SQL procedure sUCcessfully completed.

Elapsed: 00:00:40.46

SQL> truncate table test;

Table truncated.

Elapsed: 00:00:52.72

大约时间用了40秒.

再看正常日志生成下:

SQL> connect / as sysdba

Connected.

SQL> alter system set "_disable_logging"=false;

System altered.

Elapsed: 00:00:00.05

SQL> shutdown immediate;

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL> startup

ORACLE instance started.

Total System Global Area 286755168 bytes

Fixed Size 731488 bytes

Variable Size 167772160 bytes

Database Buffers 117440512 bytes

Redo Buffers 811008 bytes

Database mounted.

Database opened.

SQL> show parameter disable

NAME TYPE VALUE

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

_disable_logging boolean FALSE

SQL> connect eygle/eygle

Connected.

SQL> set timing on

SQL>

SQL> begin

2 for i in 1 .. 10000 loop

3 insert into test select * from dba_objects where rownum < 101;

4 commit;

5 end loop;

6 end;

7 /

PL/SQL procedure successfully completed.

Elapsed: 00:01:54.04

SQL>

SQL> truncate table test;

Table truncated.

Elapsed: 00:01:01.56

此时大约用时1分54秒.

两者差距为: 114 / 40 = 2.85 倍.

我们可以看出两者的差距是显著的.不作过多测试了,就此打住.大家有爱好的可以自己测试一下.

以上测试的环境为:

SQL> select * from v$version;

BANNER

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

Oracle9i Enterprise Edition Release 9.2.0.4.0 - 64bit Production

PL/SQL Release 9.2.0.4.0 - Production

CORE 9.2.0.3.0 Production

TNS for Solaris: Version 9.2.0.4.0 - Production

NLSRTL Version 9.2.0.4.0 - Production

原文地址:http://www.eygle.com/archives/2006/04/disable_logging_performance.html

 
 
 
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