The vacuum pressure is real. Using a system with the skip locked technique + polling caused massive DB perf issues as the queue depth grew. The query to see the current jobs in the queue ended up being the main performance bottleneck, which cause slower throughput, which caused a larger queue depth, which etc.

Scaling the workers sometimes exacerbates the problem because you run into connection limits or polling hammering the DB.

I love the idea of pg as a queue, but I'm a more skeptical of it after dealing with it in production