Error
Error Code:
3030
MySQL Error 3030: Replica Worker Stopped, Commit Order Preserved
Description
This error indicates that a MySQL replica worker thread has stopped because a *previous* worker thread encountered an error, specifically when the `replica-preserve-commit-order` option is enabled. To maintain data consistency and commit order, the last transaction executed by the current stopped worker is intentionally left uncommitted.
Error Message
Replica worker has stopped after at least one previous worker encountered an error when replica-preserve-commit-order was enabled. To preserve commit order, the last transaction executed by this thread has not been committed. When restarting the replica after fixing any failed threads, you should fix this worker as well.
Known Causes
4 known causesPrior Replica Thread Failure
A preceding worker thread on the replica encountered an unhandled error, triggering the current worker to stop.
Commit Order Preservation Active
The `replica-preserve-commit-order` option is enabled, which mandates that replica threads stop if a prior thread fails to ensure transactional integrity.
Uncommitted Transaction State
The current worker's last transaction was intentionally left uncommitted to uphold the `replica-preserve-commit-order` guarantee.
Underlying Replication Issues
The root cause of the previous worker's failure could be due to various replication problems like data corruption, network interruptions, or misconfigurations.
Solutions
3 solutions available1. Identify and Resolve the Cause of the Initial Worker Error advanced
The primary cause of this error is a preceding worker failure; resolving that is paramount.
1
Examine the error logs on the replica server. Look for errors that occurred *before* error 3030. These will typically be related to the first worker that failed. Common causes include data inconsistencies, network issues, or deadlocks.
2
Once the initial error is identified, implement the appropriate fix. This might involve correcting data on the source, resolving network connectivity problems, or adjusting transaction isolation levels. For example, if a deadlock was detected, you might need to re-evaluate your application's transaction logic.
3
After addressing the root cause of the initial worker failure, restart the replica threads. You can do this by stopping and then starting the replica. Ensure all previously failed worker threads are also restarted.
STOP REPLICA;
START REPLICA;2. Manually Commit the Last Transaction of the Stopped Worker medium
If the initial error is complex or difficult to immediately resolve, you can manually commit the pending transaction.
1
Identify the specific transaction that was being processed by the stopped worker. This might require examining the replica's relay log or the source's binary log for the last executed event before the stop.
2
Use the `SET GLOBAL SQL_LOG_BIN = 0;` command to temporarily disable binary logging on the replica. This is crucial to avoid replicating the commit statement itself, which could lead to infinite loops or further inconsistencies.
SET GLOBAL SQL_LOG_BIN = 0;3
Execute the COMMIT statement to finalize the transaction. Be absolutely certain this is the correct transaction to commit, as this bypasses the normal replication process for this specific transaction.
COMMIT;4
Re-enable binary logging by setting `SQL_LOG_BIN` back to 1.
SET GLOBAL SQL_LOG_BIN = 1;5
Restart the replica threads. Ensure that any other workers that previously failed are also restarted.
START REPLICA;3. Reset Replica State and Re-synchronize advanced
As a more drastic measure, reset the replica and re-synchronize from a known good state.
1
Stop the replica threads.
STOP REPLICA;2
Reset the replica's state. This will clear its current replication position and any cached transactions.
RESET REPLICA ALL;3
Take a fresh backup or snapshot of the source server.
4
Restore the backup to the replica server. Ensure the replica is in a consistent state after the restore.
5
Reconfigure the replica to connect to the source server using the correct replication credentials and the position from the fresh backup.
CHANGE REPLICATION SOURCE TO SOURCE_HOST='<source_host>', SOURCE_USER='<replication_user>', SOURCE_PASSWORD='<replication_password>', SOURCE_LOG_FILE='<log_file_name>', SOURCE_LOG_POS=<log_position>;6
Start the replica threads.
START REPLICA;