Biggest thing to watch out with this approach is that you will inevitably have some failure or bug that will 10x, 100x, or 1000x the rate of dead messages and that will overload your DLQ database. You need a circuit breaker or rate limit on it.

> FOR UPDATE SKIP LOCKED

Learned something new today. I knew what FOR UPDATE did, but somehow I've never RTFM'd hard enough to know about the SKIP LOCKED directive. Thats pretty cool.

Another day, another “Using PostgreSQL for…” thing it wasn’t designed for. This isn’t a good idea. What happens when the queue goes down and all messages are dead lettered? What happens when you end up with competing messages? This is not the way.

Segment uses MySQL as queue not even as DLQ. It works at their scale. So there are many (not all) systems that can tolerate this as queue.

I have simple flow: tasks are order of thousands an hour. I just use postgresql. High visibility, easy requeue, durable store. With appropriate index, it’s perfectly fine. LLM will write skip locked code right first time. Easy local dev. I always reach for Postgres for event bus in low volume system.