PS：这些DG实现都是建立在我之前DG博客的基础上的

此时备库是mount状态

备库打开至open，然后设置成RTA模式

20:10:00 SYS @ gotime >alter database open;
Database altered.
Elapsed: 00:00:00.33
20:10:09 SYS @ gotime >select status from v$instance;
STATUS
------------
OPEN
1 row selected.
Elapsed: 00:00:00.01
20:10:23 SYS @ gotime >select name,open_mode,database_role,protection_mode from v$database;
NAME OPEN_MODE DATABASE_ROLE PROTECTION_MODE
--------- -------------------- ---------------- --------------------
SLOW READ ONLY PHYSICAL STANDBY MAXIMUM AVAILABILITY
1 row selected.
Elapsed: 00:00:00.01
20:11:02 SYS @ gotime >recover managed standby database using current logfile disconnect;
Media recovery complete.

此时备库的告警日志信息

Serial Media Recovery started
Managed Standby Recovery starting Real Time Apply
Waiting for all non-current ORLs to be archived...
All non-current ORLs have been archived.
Media Recovery Waiting for thread 1 sequence 35 (in transit)
Recovery of Online Redo Log: Thread 1 Group 4 Seq 35 Reading mem 0
Mem# 0: /u01/app/oracle/oradata/gotime/standby04.log
Completed: ALTER DATABASE RECOVER managed standby database using current logfile disconnect

主库上开始一些DML操作并提交，测试是否成功，备库能否能够在提交瞬间作出反应，立即同步呢？？

20:13:05 SYS @ slow >select * from t2017;
DEPTNO DNAME LOC
---------- -------------- -------------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
8 rows selected.
Elapsed: 00:00:00.00
20:13:21 SYS @ slow >create table t2018 as select * from t2017 where deptno < 30;
Table created.
Elapsed: 00:00:00.03
20:14:58 SYS @ slow >commit;
Commit complete.
Elapsed: 00:00:00.00
20:15:02 SYS @ slow >

答案是确定的，说明成功了，备库能对主库commit的DML操作立即同步，做出反应！！！

-----------------------------------备库重新启动之后，Real Time Apply 消失 -------------------------------------------------------

将备库由Real Time Apply 状态重新启动，然后打开至open，进行测试

主库创建DML操作，进行测试，是否备库重新启动之后，Real Time Apply 消失....

20:31:13 SYS @ slow >create table t2000 as select * from t2017 where deptno < 20;
Table created.
Elapsed: 00:00:00.06
20:31:29 SYS @ slow >commit;
Commit complete.
Elapsed: 00:00:00.00
20:31:32 SYS @ slow >select * from t2000;
DEPTNO DNAME LOC
---------- -------------- -------------
10 ACCOUNTING NEW YORK
10 ACCOUNTING NEW YORK
2 rows selected.
Elapsed: 00:00:00.00
20:33:42 SYS @ slow >

此时备库的状态是open的，read only的，但是无法查询主库提交DML的数据，Real Time Appy 消失！！！

ITPub博客

physical DB Real Time Apply（RTA实时应用）