When encountering error 25P02: In Failed SQL Transaction in PostgreSQL, it means you're attempting an operation within a transaction that has already failed. Here’s what to do:
- Identify the Failed Transaction: Start by checking your application's logs to identify the SQL query that caused the initial failure. This is crucial for understanding why the transaction failed.
- Check PostgreSQL Logs: Look into the PostgreSQL logs for more details on the error. Use the command:
tail -f /var/log/postgresql/postgresql-<version>-main.log
- Replace
<version> with your PostgreSQL version. - Rollback the Transaction: If your session is stuck in a failed transaction, you need to manually rollback the transaction. Execute:
ROLLBACK;
- This command will exit the failed transaction and allow you to start a new one.
- Analyze the Error: Once you’ve identified the failed query and rolled back, analyze the error message provided in the logs to understand why the transaction failed.
- Check Database Health:
- Inspect disk space, using:
df -h
- Check if PostgreSQL is running out of connections:
SELECT max_conn, used, res_for_super, max_conn - used - res_for_super AS left_for_normal
FROM (SELECT setting::int AS max_conn FROM pg_settings WHERE name = 'max_connections') t1,
(SELECT COUNT(*) AS used FROM pg_stat_activity) t2,
(SELECT setting::int AS res_for_super FROM pg_settings WHERE name = 'superuser_reserved_connections') t3;
- Retry the Operation: After understanding and fixing the cause of the initial failure, retry your SQL operation. If it’s part of an application flow, ensure transactions are correctly managed to commit or rollback based on success or failure.
Remember, always ensure any fix or changes you make are tested in a development environment before applying them to production.
