Avoiding PostgreSQL Row-Level Lock Deadlocks Through Ordered Acquisition and NOWAIT

High-throughput systems that update interdependent rows concurrently often hit PostgreSQL deadlocks (SQLSTATE 40P01) or lock timeouts (SQLSTATE 55P03). The article argues that when workers acquire FOR UPDATE locks in inconsistent orders, circular waits form and the database aborts one transaction. Its proposed remedy is to sort lock keys deterministically before querying, which removes circular dependencies. Pairing this with NOWAIT and structured exception handling lets workers fail fast and roll back rather than exhaust connection pools. The piece also includes a Python example that attempts to verify this behavior across threads, along with a runtime dependency installer that the author presents as a convenience.