DATA Duplication |op : c & U
Laxmi manohar Reddy
HI
I am using Debezium Oracle Connector (upgraded from version 2.7.3 to 3.x) to capture CDC events from Oracle 19c to Kafka. During initial snapshot, data is captured correctly. However, in the streaming mode, whenever I insert a new row in the source table, Debezium emits two events for that record:
A create event (op: c) with expected data
An immediate update event (op: u) where some columns (notably RELATEDPARTY) have a before value of "__debezium_unavailable_value" and an after value with actual data (or null)
This pattern causes duplicate events and downstream processing issues.
What I Have Tried:
Enabled explicit before.image.enabled=true in connector configuration to capture before states.
Excluded problematic columns using column.exclude.list, which reduces duplicates but loses column data.
Verified Oracle supplemental logging and user privileges (LOGMINING, SELECT).
Upgraded to latest stable Debezium Oracle connector.
Investigated Oracle triggers or post-insert update logic.
What I Need Help With:
How to reliably avoid duplicate op: c and op: u events caused by placeholder before values without losing update event fidelity?
Are there best practices or configurations in Debezium or Oracle to get full consistent CDC events without spurious duplicates?
jiri.p...@gmail.com
Chris Cranford
As I mentioned on Zulip about this, it's because your table has a CLOB column and you have not set `lob.enabled` as `true`. If you enable LOB tracking, the connector will identify these two operations for the same logical row and combine them into a single event as you might expect.
-cc
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