1. Identify the cause of the PostgreSQL 39P01 error:The PostgreSQL 39P01 error is caused by a deadlock situation, which occurs when two or more transactions are waiting for each other to finish before they can proceed. To identify the cause of the error, you can use the following code snippet to view the current locks in the database:

\xSELECT * FROM pg_locks;

2. Resolve the deadlock:Once the cause of the deadlock has been identified, you can use the following code snippet to resolve the deadlock:

SELECT pg_terminate_backend(pid) FROM pg_locks WHERE pid <> pg_backend_pid();

3. Monitor the database for future deadlocks:To prevent future deadlocks, it is recommended to use an automated database observability tool. This tool can monitor the database for any potential deadlocks and alert you when they occur. This allows you to quickly identify and resolve any deadlocks before they cause any major issues.