- Identify the cause of the duplicate transaction by checking the application logs or MySQL logs to see if multiple requests are being sent unintentionally. Use the MySQL query:
SHOW ENGINE INNODB STATUS;
Look for the `LATEST DETECTED DEADLOCK` section to identify transactions that were involved in the error.
- Check for duplicate entries in the table that might be causing the error. Depending on your table structure, you might run a query like:
SELECT column_name, COUNT(*)
FROM table_name
GROUP BY column_name
HAVING COUNT(*) > 1;
Replace `columnname` and `tablename` with the actual column and table names involved in the transaction.
- If the duplicate transaction involves a unique constraint or primary key, verify the data that is being inserted. Make sure that the data being inserted or updated does not violate any unique constraints.
- Temporarily increase the verbosity of the MySQL error log to capture more detailed information about the error. Use the following command to adjust the logging level:
SET GLOBAL logerrorverbosity = 3;
After investigating, remember to set it back to its original level to avoid excessive logging.
- If possible, manually retry the transaction with a delay to see if it was a transient issue. This can be done directly via your application logic or manually through a MySQL client if you were directly executing the transaction.
6. If the duplicate error is related to a specific application function, review the code path for that functionality to ensure it does not inadvertently attempt the same transaction multiple times under certain conditions.
