23.09.2026 Problem:
Debezium Oracle source connectors were intermittently failing with ORA-01013 (“user requested cancel of current operation”) every few hours. Restarting the connector temporarily restored replication. Connector configuration attempts included custom log mining parameters and raising database.query.timeout.ms from the default 600000 ms to 1200000 ms; the Debezium docs warn that setting database.query.timeout.ms to 0 disables the driver timeout but may impact database performance. Clients reported connector logs showing query cancellations that coincided with long-running LogMiner operations.
Observed signals available during the incident: a raw connector stack trace surfaced a timeout wrapper in the JDBC driver (indicating a driver-side timeout), connector runtime configuration showed database.query.timeout.ms absent (thus using the 600s default), and Oracle alert logs contained a large number of “checkpoint incomplete” events. DBA checks showed redo log groups sized at 1GB each and frequent log switches; Unified Auditing was not enabled so legacy audit views were empty.
Process:
Step 1: Capture the failing stack trace and classify the exception
Collected the raw connector stack trace to identify the exception class and failing method. The trace included a java.sql.SQLTimeoutException propagating through the OracleStatement.doExecuteWithTimeout path, which differentiated a driver-enforced timeout from a server-issued cancel. This classification focused the investigation on whether query runtime exceeded Debezium’s JDBC timeout or an external process killed the session.
Step 2: Verify connector runtime configuration
Queried the Connect REST API to read the active connector configuration rather than relying on files. The database.query.timeout.ms property was absent (null), confirming the connector was using the default 600000 ms. Although the operator had experimented with a higher value (1,200,000 ms), the active runtime state remained at default for the observed failures—important because the driver timeout window matched the observed cancellation behavior.
Step 3: Rule out server-side administrative kills
Checked audit and diagnostic surfaces to find external KILL/ALTER SYSTEM events. V$OPTION showed unified auditing was not enabled, so DBA_AUDIT_TRAIL returned no evidence of an external ALTER SYSTEM cancel. Attempts to query some diagnostic views required additional privileges; results and permissions checks helped eliminate scripted session kills as the likely primary cause.
Step 4: Inspect alert log and redo activity for LogMiner pressure
Scrubbed the Oracle alert log for “checkpoint incomplete” messages and queried v$log/v$log_history to measure log switch frequency. The alert log contained a very high count of checkpoint incomplete events and v$log showed many 1GB redo groups with frequent switches over recent days. These signals indicated checkpoint starvation and heavy redo generation, which can stall LogMiner reads and make LogMiner queries run long enough to hit JDBC timeouts.
Step 5: Run memory and network diagnostics to exclude other causes
Ran corrected AWR-derived queries to examine PGA and SGA snapshots over the incident window and validated that no sqlnet.ora timeouts were configured. Memory reports did not show a reproducible ORA-04030/ORA-04031 pattern that would explain sudden session kills, and network timeouts were not set on the listener, narrowing the root cause to redo/checkpoint interaction with LogMiner rather than network or memory throttling.
Step 6: Synthesize evidence and implement the remediation
Correlating the JDBC timeout classification with the alert log and redo metrics showed that LogMiner queries were being delayed by frequent, incomplete checkpoints and rapid log switches; the Debezium JDBC timeout therefore expired and the driver raised a SQLTimeoutException (manifesting as ORA-01013). Based on that, the team applied database.query.timeout.ms: “0” to disable the driver-enforced fetch timeout on the connector, while verifying that log.mining.query.filter.mode was set to in (since literal table include lists were used) to filter changes at the Oracle query level and reduce JDBC payload size. Obsolete Debezium 3.x tuning properties (log.mining.batch.size., log.mining.sleep.time.) were also removed during cleanup.
Solution:
The fix was made entirely on the Debezium connector side. Setting database.query.timeout.ms to 0 stopped the connector from cancelling long queries during peak load. Setting log.mining.query.filter.mode to in allowed Oracle to filter data directly inside the SQL query, reducing the amount of data transferred over JDBC during heavy activity (over 500 GB/day of redo).
Architecturally, filtering at the database level lowers network and memory usage, while disabling the timeout stops temporary slow reads from crashing the connector.
Conclusion:
After disabling the timeout and optimizing query filtering, ORA-01013 errors completely stopped. CDC replication stayed stable, data reached Kafka with low lag, and no complex changes to Oracle redo logs were needed.