[aib]

I tried using a PostgreSQL SKIP LOCKED queue once, turned out to be a mistake.

It was a queue for a distributed worker pool. The simpler alternatives I was used to at the time (RabbitMQ) did not support joining (i.e. run task Y when all of X1~X20 are complete) and therefore every task was stored in the database, anyway. I don't remember the exact numbers, but it was a light/moderate load--thousands, maybe tens of thousands of rows per day. It ran smoothly with an external message queue. I'd vacuum maybe every 4 months.

For one iteration, I decided to try using PostgreSQL as the queue system as well, to decrease the number of moving parts. It performed fine for a bit, then slowed to a crawl. I was sure I was doing something wrong--except every guide told me this was how to use a table as a queue. If I missed anything, it must've been PG-as-a-queue-specific.

[d0mine]

Was the vacuum enabled? Were there long orphaned transactions?