对于性能的影牛

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:

archives/2006/04/more_about_disable_ml

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 bytes

Fixed Size 731488 bytes

Variable Size bytes

Database Buffers bytes

Redo Buffers 811008 bytes

Database mounted.

Database opened.

SQL connect eygle/eygle

Connected.

SQL show parameter disable

家电企业都有动力来支持电商渠道的发展。因此 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 bytes

Fixed Size 731488 bytes

Variable Size bytes

Database Buffers 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.大家有兴趣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

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