Downgrading from Mirror Replication Agent for Oracle version 15.0 to version 12.6

This procedure assumes that you are using a Mirror Replication Agent for Oracle version 15.0 instance. If the Mirror Replication Agent for Oracle version 12.6 instance no longer exists, create one using the Mirror Replication Agent for Oracle version 12.6 mro_admin command.

To downgrade from Mirror Replication Agent for Oracle version 15.0 to version 12.6

Be sure that the appropriate Oracle JDBC driver is in your CLASSPATH.

No other Oracle drivers are allowed in the CLASSPATH.
Prevent users (other than the Mirror Replication Agent for Oracle version 15.0 user) from accessing the primary database.
Verify that the Mirror Replication Agent for Oracle version 15.0 instance is in Replicating state and allow replication to finish. To verify that replication is completed:
- Periodically issue the ra_statistics command, watching until the following statistics are zero (0):
  - Input queue size
  - Output queue size
- When they are both queue sizes are zero, note the Last QID Sent from the last set of statistics.
- Issue the ra_locator update command to allow Mirror Replication Agent to retrieve the truncation point from Replication Server.
- Wait, and then issue the ra_locator command and compare the displayed locator with that of the Last QID Sent. If they are different, wait and repeat this step.
Quiesce the Mirror Replication Agent for Oracle version 15.0 instance.
In the Mirror Replication Agent for Oracle version 15.0 instance, de-initialize the Mirror Replication Agent:
```
ra_deinit, force
```
Shut down the Mirror Replication Agent for Oracle version 15.0 instance.
Start and log in to the Mirror Replication Agent for Oracle version 12.6 instance.
Test the primary database connection:
```
test_connection PDS
```
Initialize the primary database:
```
pdb_init
```
Any configuration properties that you have modified after migration may need to be reset.
Quiesce the primary database:
```
pdb_quiesce hold
```
Initialize the Mirror Replication Agent for Oracle 12.6:
```
ra_init
```
This automatically marks all the objects for replication. Any objects that you want to unmark must be re-entered.
Allow users access to the primary database:
```
pdb_quiesce release
```
Log in to the RSSD and set the Replication Server’s locator to “0”:
```
rs_zeroltm source_ds, source_db
```
where source_ds and source_db match the Mirror Replication Agent for Oracle version 12.6 instance’s values for the rs_source_ds and rs_source_db parameters.

The rs_source_ds and rs_source_db values were migrated from Mirror Replication Agent for Oracle version 15.0 and should not be changed.
In the Mirror Replication Agent for Oracle version 12.6 instance, resume replication:
Log out of the Mirror Replication Agent for Oracle version 12.6 instance.
If you created a new interfaces or sql.ini entry when you upgraded to Mirror Replication Agent for Oracle version 15.0, update the entry so the Mirror Replication Agent for Oracle version 12.6 instance name is again associated with the old Mirror Replication Agent for Oracle version 12.6 instance machine and port number.
Revert the Oracle logging properties back to your desired setup in the primary database.
Revoke any additional privileges that were granted to the Mirror Replication Agent primary database user for the upgrade in the primary database.