Prepare the Third Source Database to Send Redo to the Mining Database

To prepare the third source database to send redo to the mining database:

Make sure that DBMS3 source database is running with the required compatibility.

select name, value from v$parameter where name = 'compatible';

NAME                    VALUE
---------               ---------------------
compatible              11.1.0.0.0

The minimum compatibility setting required from capture is 11.1.0.0.0.

Set DG_CONFIG at DBMS3 source database.

ALTER SYSTEM SET LOG_ARCHIVE_CONFIG='DG_CONFIG=(dbms3, dbmscap)';

Set up redo transport at DBMS3 source database. Because DBMS3 is the source that will send its online redo logs to the standby redo logs at the downstream mining database, do not specify a TEMPLATE clause.
```
ALTER SYSTEM
SET LOG_ARCHIVE_DEST_2='SERVICE=DBMSCAP.EXAMPLE.COM ASYNC OPTIONAL NOREGISTER
VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE)DB_UNIQUE_NAME=dbmscap';
```

Enable the downstream destination.

ALTER SYSTEM SET LOG_ARCHIVE_DEST_STATE_2=ENABLE;