Comment by riku_iki
3 years ago
article says he also uses "order by" clause, but I am wondering if it will severely limit throughput since all messages will need to be sorted on each lookup, but this probably can be solved by introducing index.
3 years ago
article says he also uses "order by" clause, but I am wondering if it will severely limit throughput since all messages will need to be sorted on each lookup, but this probably can be solved by introducing index.
It seems strictly worse to use ORDER BY in this case, since if you're using SKIP LOCKED you should be doing parallel processing anyway, and if you're doing parallel processing, ordering is already going out the window.
Parallel or not, the order is of importance in any queue system.
Unless you can guarantee that the processing time of each job is exactly the same, if you have multiple workers processing the same queue, you can’t order anything except the start time.
You can use locks to effectively break the queue into sub queues so that each sub queue is only being processed by 1 worker. Then you can order that sub queue.
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You have no ordering guarantees, so how can order be important? If 4 work items are scheduled on 4 independent workers, you have no guarantee which will start first or finish first.
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