DML operations on Active Data Guard standby in Oracle 19c

The DML operations is an Active Data Guard only feature enables DML operations on the standby database to be redirected to the primary to accommodate infrequent writes by reporting applications running against Active Data Guard standby database.

This DML feature introduced in Oracle 19c, this includes DML statements that are part of PL/SQL blocks.

The DML on the standby database will have below steps

• The user executes DML against open standby database.
• DML will be automatically redirects to the primary database.
• The DML will be applied on the primary Datable
• The redo info related change is streamed back to the standby database.
• The application change based redo info completes the DML and data is available for the client.

There are two methods to configure DML Redirection with the help of ADG_REDIRECT_DML parameter.

1. The DML Redirect can be configured at system level, this will apply to all sessions connection to the standby database

Run below command for SYSTEM LEVEL DML Redirection
SQL> ALTER SYSTEM SET ADG_REDIRECT_DML=TRUE SCOPE=BOTH;

2. You can overwrite the system level parameter with alert session command to enable the DML redirect for the current session only.

Run below command to enable SESSION LEVEL DML Redirection 

SQL>ALTER SESSION ENABLE ADG_REDIRECT_DML;

Thanks & Regards

http://oracleracexpert.com