Oracle10g增加了DATA GUARD的日志实时应用功能，11g添加了实时查询功能。这两个功能可以同时应用。
DATA GUARD的建立：
http://yangtingkun.itpub.net/post/468/388465Oracle11新特性——DATA GUARD打开模式下应用
归档：
http://yangtingkun.itpub.net/post/468/388599对于PRIMARY
数据，只需要将对应的LOG_ARCHIVE_DEST改为同步方式。为了更好的说明
问题，首先将归档日志切换一下：
SQL> alter system set log_archive_dest_2 =
2 'SERVICE=ora11g_s SYNC VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=ora11g_s';
系统已更改。
SQL> alter system switch logfile;
系统已更改。
下面登陆STANDBY
数据库，添加STANDBY LOGFILE，并修改初始化参数，使得STANDBY数据库可以处理STANDBY LOGFILE：
$ sqlplus "/ as sysdba"
SQL*Plus: Release 11.1.0.6.0 - Production on Thu Sep 27 18:52:10 2007
Copyright (c) 1982, 2007, Oracle. All rights reserved.
Connected to an idle instance.
SQL> startup mount
ORACLE instance started.
Total System Global Area 267825152 bytes
Fixed Size 1299316 bytes
Variable Size 150998156 bytes
Database Buffers 113246208 bytes
Redo Buffers 2281472 bytes
Database mounted.
SQL> set pages 100 lines 120
SQL> col member format a80
SQL> select group#, member from v$logfile;
GROUP# MEMBER
---------- --------------------------------------------------------------------
1 /data/oracle/oradata/ora11g/ORA11G_S/onlinelog/o1_mf_1_3f5dsz0v_.log
1 /data/oracle/flash_recovery_area/ORA11G_S/onlinelog/o1_mf_1_3f5dszg1_.log
2 /data/oracle/oradata/ora11g/ORA11G_S/onlinelog/o1_mf_2_3f5dt1vl_.log
2 /data/oracle/flash_recovery_area/ORA11G_S/onlinelog/o1_mf_2_3f5dt26o_.log
3 /data/oracle/oradata/ora11g/ORA11G_S/onlinelog/o1_mf_3_3f5dt3gn_.log
3 /data/oracle/flash_recovery_area/ORA11G_S/onlinelog/o1_mf_3_3f5dt3yj_.log
6 rows selected.
SQL> select group#, bytes from v$log;
GROUP# BYTES
---------- ----------
1 52428800
3 52428800
2 52428800
SQL> alter database add standby logfile
2 ('/data/oracle/oradata/ora11g/ORA11G_S/onlinelog/sredo1.log') size 50m;
Database altered.
SQL> alter database add standby logfile
2 ('/data/oracle/oradata/ora11g/ORA11G_S/onlinelog/sredo2.log') size 50m;
Database altered.
SQL> alter database add standby logfile
2 ('/data/oracle/oradata/ora11g/ORA11G_S/onlinelog/sredo3.log') size 50m;
Database altered.
SQL> alter database add standby logfile
2 ('/data/oracle/oradata/ora11g/ORA11G_S/onlinelog/sredo4.log') size 50m;
Database altered.
SQL> alter system set log_archive_dest_3 =
2 'LOCATION=/data/oracle/oradata/ora11g/archivelogstand
3 VALID_FOR=(STANDBY_LOGFILES,STANDBY_ROLES) DB_UNIQUE_NAME=ora11g_s';
System altered.
SQL> alter database open;
Database altered.
SQL> alter database recover managed standby database
2 using current logfile disconnect from session;
Database altered.
至此，DATA GUARD的REAL TIME APPLY已经配置完成。下面检查一下DATA GUARD是否正常工作。登陆PRIMARY KEY进行数据修改，并提交：
SQL> select * from t_standby;
no rows selected
SQL> insert into t_standby select * from tab;
4 rows created.
SQL> commit;
Commit complete.
登陆STANDBY数据库，检查修改是否已经同步过来：
SQL> conn yangtk/yangtk
SQL> select * from t_standby;
TNAME TABTYPE CLUSTERID
------------------------------ ------- ----------
T TABLE
T_SESSION TABLE
T_SESSION_STAT TABLE
T_STANDBY TABLE
现在数据库同时处于REAL TIME APPLY和REAL TIME QUERY状态。
