Having and caring about are different things.

I care about money, I dont have money.

Here you go. One of the first tutorials explaining how SKIP LOCKED works in Postgres implants a job “queue” that doesn’t have an order by clause. https://www.pgcasts.com/episodes/the-skip-locked-feature-in-...

I’m not confusing anything. I’ve seen random selection “job queues” implemented many times. As long as you truly don’t care about start order, it’s fine to trade it for increased throughout.

> doesn’t have an “order by” clause

Does that mean it doesn't have any order or that you don't care about order?

Also we are arguing over whether pg suffices as a queue implementation, and you use itself as an exhibit?

It means that you are telling pg that you don’t care about order, so it is free to optimize the query in whatever way it wants to. The order can change query to query depending on numerous external factors.

I’m not using pg itself as an example. I’m using a specific implementation of a “job queue” built with pg.

I’ve seen and you can search for and find many implementations of “job queues” using relational databases where job start order guarantees are traded away for throughput.