[ffsm8]

You're responsible for writing the query that selects the tasks to process, so yes? You can obviously group by a common id, order by inserted and use limit 1. And if every event has to be processed in order, then you've created a system that can't be parallel, so you'll be effectively limited to a single worker.

[dkersten]

You can have multiple workers, but they all need to process all events. So it’s not suitable for parallelisation of work (how can it be, if total ordering is required), but it can be used where different workers consume the queue in different ways (eg for synchronising different services).