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Postgres LISTEN/NOTIFY does not scale

(www.recall.ai)
570 points davidgu | 1 comments | 07 Jul 25 14:05 UTC | HN request time: 0.257s | source
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leontrolski ◴[10 Jul 25 21:00 UTC] No.44525560[source]▶
I'd be interested as to how dumb-ol' polling would compare here (the FOR UPDATE SKIP LOCKED method https://leontrolski.github.io/postgres-as-queue.html). One day I will set up some benchmarks as this is the kind of thing people argue about a lot without much evidence either way.

Wasn't aware of this AccessExclusiveLock behaviour - a reminder (and shameless plug 2) of how Postgres locks interact: https://leontrolski.github.io/pglockpy.html

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1. RedShift1 ◴[10 Jul 25 21:29 UTC] No.44525828[source]▶
I use polling with back off up to one minute. So when a workload is done, it immediately polls for more work. If nothing found, wait for 5 seconds, still nothing 10 seconds, ... until one minute and from then on it polls every minute until it finds work again and the back off timer resets to 0 again.