Issue with Multiple Debezium/XStream Connectors on Oracle CDB with RAC

[Norberto da Silva Prado]

Has anyone encountered this scenario with Kafka Debezium connectors using XStream?

I have two connectors configured with XStream—each with a capture and two outbound—pointing to an Oracle CDB database with RAC, using SCAN and a TNS configuration that also uses SCAN.

Each connector targets a different schema, located in separate PDBs, but within the same CDB instance.

Here’s the behavior I’m observing:

• The first connector starts up normally but does not generate the expected topics.
• The second connector also starts, but fails shortly after, showing the following: [ERROR] 2025-07-03 14:58:34,970 [debezium-oracleconnector-oracle_source_xst_sgm_mts-change-event-source-coordinator] io.debezium.pipeline.ErrorHandler setProducerThrowable - Producer failure oracle.streams.StreamsException: ORA-26913: must connect to instance 3 where XStream Outbound server "XOUT_SERVER_SGMMTSPR" is running

Has anyone seen this before or have any idea what might be causing it? Could it be related to how SCAN is resolving connections or how the outbound servers are configured in the RAC environment?

[Chris Cranford]

Hi

While Debezium will use the driver's SCAN options for connectivity and initial snapshots as this is all pure JDBC and your target is the database service, when you transition to streaming, Debezium interfaces with XStream, which cannot benefit from SCAN.

The underlying reason is that XStream is not a typical database service, its a service process that exists solely on one of N RAC instances on the cluster, and so for the client to successfully connect, you must point specifically to that instance.

So for XStream deployments, you have two options:

1. Configure the connector to use the physical IP addresses of the instance that runs XStream.
2. Have the DBA team create a specific TNS service that is pinned to that Oracle RAC node instance and connect to that service.

As to your first point, where it starts but does not generate expected topics, have you tried enabling DEBUG logging and if so, could you share those logs?

Thanks,
-cc

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