ORACLE DATAGUARD

Some day to day commands for Datagaurd:

➤How to start log apply service in standby database?

SQL>Alter database recover managed standby database disconnect from session;

Here, "disconnect from session" to instruct the session to come out of the current SQL session else it will be hung until the recovery is completed

➤How to check the log apply service is working fine or not?

SQL>select process,status,sequence# from v$managed_standby;

Note: Never check the archive sync with the command "archive log list" , it may give the wrong details. Always check it using v$managed_standby view.

➤To stop the log apply service?

SQL>Alter database recover managed standby database cancel;

Verify it by running below command

 SQL>select process,status,sequence# from v$managed_standby; 

Alternatively,  you can verify the mrp process.It will show no mrp process running for the instance. 

ps -ef|grep mrp

Stop log apply using DGBROKER

DGMGRL>edit database <standby_dbname> set state=apply-off;

➤How to start the redo apply in real time in foreground?

SQL>alter database recover managed standby database;

Note: In above command delay attribute is ignored

If you want to start with delay, use below command:

SQL>alter database recover managed standby database using archived logfile disconnect;

Note:Delay attribute must be set at primary and standby database

Start using Broker

DGMGRL>edit database <standby_dbname>  set state=apply-on;

Redo apply delay parameter

edit database <standby_dbname> set DelayMins=10;

➤ What happens when delay is mentioned?

#MRP waits for a specified time before it applies the redo

# can be used to protect corrupted data to be applied from primary to standby

# report will get generated until the apply is done with real time data

# set parmeter DELAY in log_archive_dest_n parameter 

➤ How to opverride the delay service and apply redo:

SQL>alter database recover managed standby database nodelay;