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_disable_logging对于非归档数据库的影响

来源:互联网网民  宽屏版  评论
2006-04-20 05:58:30

1. _disable_logging对于非归档数据库的影响

首先确定数据库当前是非归档模式:

lunar@TSMISC01> archive log list

Database log mode No Archive Mode

Automatic archival Enabled

Archive destination /oracle/oradata/TSMISC01/archive

Oldest online log sequence 0 之前被删除或者被初始化过

Current log sequence 158

lunar@TSMISC01>

查看online redo log 的相关信息:

lunar@TSMISC01> select * from v$log;

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

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

1 1 0 2097152 2 YES UNUSED 0

2 1 158 104857600 2 NO CURRENT 49355946 12-APR-06

3 1 157 104857600 1 NO INACTIVE 49355943 12-APR-06

Elapsed: 00:00:00.00

lunar@TSMISC01> select * from v$logfile;

GROUP# STATUS TYPE MEMBER

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

1 ONLINE /oracle/oradata/TSMISC01/redo11.log

2 ONLINE /oracle/oradata/TSMISC01/redo02.log

3 ONLINE /oracle/oradata/TSMISC01/redo03.log

2 ONLINE /oracle/oradata/TSMISC01/redo02_2.log

1 ONLINE /oracle/oradata/TSMISC01/redo12.log

Elapsed: 00:00:00.00

lunar@TSMISC01>

从这些信息我们看到,group 1 是新建的组,因此其sequence#是0,而status是 unused。还可以看到,group 2是当前数据库正在使用的online redo logfile。

现在,检查数据库中_disable_logging参数的设置:

lunar@TSMISC01> @get_param

Enter value for par: disable_logging

old 14: x.ksppinm like '%_&par%'

new 14: x.ksppinm like '%_disable_logging%'

NAME VALUE ISDEFAULT ISMOD ISADJ

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

_disable_logging FALSE FALSE FALSE FALSE

Elapsed: 00:00:00.00

lunar@TSMISC01>

可见,目前_disable_logging为false。

我们可以使用alter system 命令修改这个参数,并且可以使用scope=memory(仅在当前的系统中生效)或者scope=both(在当前的系统和spfile中都做相应的设置)来指定,让这个参数立刻生效:

lunar@TSMISC01> alter system set "_disable_logging"=true scope=memory;

System altered.

Elapsed: 00:00:00.02

lunar@TSMISC01> show parameter disable_logging

NAME TYPE VALUE

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

_disable_logging boolean TRUE

lunar@TSMISC01>

现在我们来作个测试表,创建一个大表,并向其中插入10000000 条记录,然后看看系统是否发生了日志切换,还是会发生其他什么异常情况:

lunar@TSMISC01> @big_table 10000000

Table dropped.

Elapsed: 00:00:01.33

Table created.

Elapsed: 00:00:00.13

Table altered.

Elapsed: 00:00:00.02

old 3: l_rows number := &1;

new 3: l_rows number := 10000000;

old 9: where rownum <= &1;

new 9: where rownum <= 10000000;

PL/SQL procedure successfully completed.

Elapsed: 00:01:29.89

Table altered.

Elapsed: 00:01:33.17

PL/SQL procedure successfully completed.

Elapsed: 00:03:12.77

COUNT(*)

----------

10000000

Elapsed: 00:00:02.05

lunar@TSMISC01>

现在看看日志文件的情况:

lunar@TSMISC01> select * from v$log;

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

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

1 1 162 2097152 2 NO INACTIVE 49413664 12-APR-06

2 1 161 104857600 2 NO INACTIVE 49374533 12-APR-06

3 1 163 104857600 1 NO CURRENT 49414128 12-APR-06

Elapsed: 00:00:00.19

lunar@TSMISC01> select * from v$logfile;

GROUP# STATUS TYPE MEMBER

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

1 ONLINE /oracle/oradata/TSMISC01/redo11.log

2 ONLINE /oracle/oradata/TSMISC01/redo02.log

3 ONLINE /oracle/oradata/TSMISC01/redo03.log

2 ONLINE /oracle/oradata/TSMISC01/redo02_2.log

1 ONLINE /oracle/oradata/TSMISC01/redo12.log

Elapsed: 00:00:00.04

lunar@TSMISC01>

我们看到日志已经发生了切换,数据库可以继续操作,创建大表前数据库的“当前日志是group 2”,在创建了一些大表后,当前日志已经是group 3了,且alert.log中没有任何报错信息,也没有什么异常的信息。因此,我们可以有下面的结论:在非归档模式的数据库下,不论_disable_logging是false还是true,数据库都可以继续操作,而不受该参数的影响。

 
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1. _disable_logging对于非归档数据库的影响 首先确定数据库当前是非归档模式: lunar@TSMISC01> archive log list Database log mode No Archive Mode Automatic archival Enabled Archive destination /oracle/oradata/TSMISC01/archive Oldest online log sequence 0 之前被删除或者被初始化过 Current log sequence 158 lunar@TSMISC01> 查看online redo log 的相关信息: lunar@TSMISC01> select * from v$log; GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS FIRST_CHANGE# FIRST_TIM ---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- --------- 1 1 0 2097152 2 YES UNUSED 0 2 1 158 104857600 2 NO CURRENT 49355946 12-APR-06 3 1 157 104857600 1 NO INACTIVE 49355943 12-APR-06 Elapsed: 00:00:00.00 lunar@TSMISC01> select * from v$logfile; GROUP# STATUS TYPE MEMBER ---------- ------- ------- -------------------------------------------------- 1 ONLINE /oracle/oradata/TSMISC01/redo11.log 2 ONLINE /oracle/oradata/TSMISC01/redo02.log 3 ONLINE /oracle/oradata/TSMISC01/redo03.log 2 ONLINE /oracle/oradata/TSMISC01/redo02_2.log 1 ONLINE /oracle/oradata/TSMISC01/redo12.log Elapsed: 00:00:00.00 lunar@TSMISC01> 从这些信息我们看到,group 1 是新建的组,因此其sequence#是0,而status是 unused。还可以看到,group 2是当前数据库正在使用的online redo logfile。 现在,检查数据库中_disable_logging参数的设置: lunar@TSMISC01> @get_param Enter value for par: disable_logging old 14: x.ksppinm like '%_&par%' new 14: x.ksppinm like '%_disable_logging%' NAME VALUE ISDEFAULT ISMOD ISADJ ----------------------------------- ------------------------- --------- ---------- ----- _disable_logging FALSE FALSE FALSE FALSE Elapsed: 00:00:00.00 lunar@TSMISC01> 可见,目前_disable_logging为false。 我们可以使用alter system 命令修改这个参数,并且可以使用scope=memory(仅在当前的系统中生效)或者scope=both(在当前的系统和spfile中都做相应的设置)来指定,让这个参数立刻生效: lunar@TSMISC01> alter system set "_disable_logging"=true scope=memory; System altered. Elapsed: 00:00:00.02 lunar@TSMISC01> show parameter disable_logging NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ _disable_logging boolean TRUE lunar@TSMISC01> 现在我们来作个测试表,创建一个大表,并向其中插入10000000 条记录,然后看看系统是否发生了日志切换,还是会发生其他什么异常情况: lunar@TSMISC01> @big_table 10000000 Table dropped. Elapsed: 00:00:01.33 Table created. Elapsed: 00:00:00.13 Table altered. Elapsed: 00:00:00.02 old 3: l_rows number := &1; new 3: l_rows number := 10000000; old 9: where rownum <= &1; new 9: where rownum <= 10000000; PL/SQL procedure successfully completed. Elapsed: 00:01:29.89 Table altered. Elapsed: 00:01:33.17 PL/SQL procedure successfully completed. Elapsed: 00:03:12.77 COUNT(*) ---------- 10000000 Elapsed: 00:00:02.05 lunar@TSMISC01> 现在看看日志文件的情况: lunar@TSMISC01> select * from v$log; GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS FIRST_CHANGE# FIRST_TIM ---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- --------- 1 1 162 2097152 2 NO INACTIVE 49413664 12-APR-06 2 1 161 104857600 2 NO INACTIVE 49374533 12-APR-06 3 1 163 104857600 1 NO CURRENT 49414128 12-APR-06 Elapsed: 00:00:00.19 lunar@TSMISC01> select * from v$logfile; GROUP# STATUS TYPE MEMBER ---------- ------- ------- -------------------------------------------------- 1 ONLINE /oracle/oradata/TSMISC01/redo11.log 2 ONLINE /oracle/oradata/TSMISC01/redo02.log 3 ONLINE /oracle/oradata/TSMISC01/redo03.log 2 ONLINE /oracle/oradata/TSMISC01/redo02_2.log 1 ONLINE /oracle/oradata/TSMISC01/redo12.log Elapsed: 00:00:00.04 lunar@TSMISC01> 我们看到日志已经发生了切换,数据库可以继续操作,创建大表前数据库的“当前日志是group 2”,在创建了一些大表后,当前日志已经是group 3了,且alert.log中没有任何报错信息,也没有什么异常的信息。因此,我们可以有下面的结论:在非归档模式的数据库下,不论_disable_logging是false还是true,数据库都可以继续操作,而不受该参数的影响。
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