What is Active DataGuard?
Putting a database in ReadOnly mode and LogApply mode simultaneously.
1. Start the standby database in nomount mode
SQL> startup nomount;
2. Put the database in mount mode
SQL> alter database mount standby database;
SQL> select open_mode from v$database;
OPEN_MODE
-----------------------
MOUNTED
3. Put the database in Read Only mode
SQL> alter database open read only;
Database altered.
SQL> select open_mode from v$database;
OPEN_MODE
--------------------------
READ ONLY
4. Start the log apply service on one instance with
SQL> alter database recover managed standby database using current logfile disconnect;
Database altered.
5. On both standby instances querying the open mode will give
SQL> select open_mode from v$database;
OPEN_MODE
----------------------------------
READ ONLY WITH APPLY
1. Start the standby database in nomount mode
SQL> startup nomount;
2. Put the database in mount mode
SQL> alter database mount standby database;
SQL> select open_mode from v$database;
OPEN_MODE
-----------------------
MOUNTED
3. Put the database in Read Only mode
SQL> alter database open read only;
Database altered.
SQL> select open_mode from v$database;
OPEN_MODE
--------------------------
READ ONLY
4. Start the log apply service on one instance with
SQL> alter database recover managed standby database using current logfile disconnect;
Database altered.
5. On both standby instances querying the open mode will give
SQL> select open_mode from v$database;
OPEN_MODE
----------------------------------
READ ONLY WITH APPLY
USEFUL Views
V$managed_standby
v$archive_dest
V$dataguard_status
v$archive_dest_status
v$archive_gap
v$database
v$dataguard_stats
v$database_incarnation
v$archived_log
v$datafile
v$dataguard_config
v$fs_failover_stats
v$logfile
v$log_history
v$standby_log
v$redo_dest_resp_histogram
V$managed_standby
v$archive_dest
V$dataguard_status
v$archive_dest_status
v$archive_gap
v$database
v$dataguard_stats
v$database_incarnation
v$archived_log
v$datafile
v$dataguard_config
v$fs_failover_stats
v$logfile
v$log_history
v$standby_log
v$redo_dest_resp_histogram