Also when they have two many jobs for their one table - partition the table by customer, when that's still somehow too big - shard the table across a couple DB instances. Toss in some beefy machines that can keep the tables in memory and I suspect you'd have a LOOOONG way to go before you ever really needed to get off of postgres.

In my experience, the benefits of a SQL table for a problem like this are real big - easier to see what's in the queue, manipulate the queue, resolve head-of-queue blocking problems, etc.

There is another variable of experience with the technology which seems to be high for Postgres, low for RabbitMQ…