I implemented a queue using both LISTEN/NOTIFY for notifications to the task processor and SKIP LOCKED to sift through the pending tasks in the tasks table.
I think you can eliminate polling if you don't need to retry tasks, by simply processing pending tasks at startup and then just responding to LISTEN events. However, I'm curious if there are any alternatives to polling the queue in cases where you need to support retrying tasks at a given timestamp.
I personally think polling the queue/table via queries is a very sensible pattern and not something I have a desire to remove. In theory, you could go at it via a push approach by wiring into the WAL or something but that comes with its own rats nest of issues.
I think you can eliminate polling if you don't need to retry tasks, by simply processing pending tasks at startup and then just responding to LISTEN events. However, I'm curious if there are any alternatives to polling the queue in cases where you need to support retrying tasks at a given timestamp.