Does ArcGIS support Oracle DML redirection or database links?

ArcGIS does not support DML redirection, an Oracle Active Data Guard feature, due to underlying user-defined types (UDTs) restrictions with remote databases. In Enterprise Geodatabases, ST_Geometry and SDO_Geometry are user-defined types used to store spatial data within an Oracle database. User-defined types in database links are a known restriction in Oracle, and by extension DML redirection which uses transparent database links. See: 2.1.9 Restriction on Using User-Defined Types with a Remote Database.

DML redirection uses a database link to connect to a remote database, and when DML queries on user-defined types are sent, the following error is returned: 

ORA-22804 remote operations not permitted on object tables or user-defined type columns

Queries that contain remote databases and references to a user-defined type will return a different error:

ORA-00942: table or view does not exist.

These errors are due to the remote database's inability to interpret and implement the local database type. There are further complications to user-defined types (UDTs), including the use of local variables in PL/SQL code and remote procedure calls, which ArcGIS relies heavily upon for versioning operations with the database. 

While there may be some simple database transactions that work, particularly with non-spatial data, much of the ArcGIS enterprise geodatabase functionality is impacted by this known restriction in Oracle's software.