11g Active Data Guard - enabling Real-Time Query

In 11g, Oracle introduced the Active Data Guard feature. This allows the standby database to be open in read-only mode, but still apply redo information. This means a standby can be available for querying, yet still be up to date. There are licensing implications for this feature, but the following commands show how active data guard can be enabled.

SHUTDOWN IMMEDIATE;
STARTUP MOUNT;
ALTER DATABASE OPEN READ ONLY;
ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION;
Since managed recovery continues with active data guard, there is no need to switch back to managed recovery from read-only mode in this case.

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Stop redo apply with the following command from Data Guard Broker CLI

DGMGRL> EDIT DATABASE ‘PRODDB’ SET STATE=’APPLY-OFF’;

Open standby read-only via SQL*Plus

SQL> alter database open read only;

Restart redo apply via broker CLI

DGMGRL> EDIT DATABASE ‘PRODDB’ SET STATE=’APPLY-ON’;