I don't understand the latency graph. It says it has 0.25ms consumer latency.

Then in the latency tradeof section it says end to end latency is between 1-2 seconds.

Is this under heavy load or always? How does this compare to pgmq end to end latency?

(PgQue author here)

I didn't understand nuances in the beginning myself

We have 3 kinds of latencies when dealing with event messages:

1. producer latency – how long does it take to insert an event message?

2. subscriber latency – how long does it take to get a message? (or a batch of all new messages, like in this case)

3. end-to-end event delivery time – how long does it take for a message to go from producer to consumer?

In case of PgQ/PgQue, the 3rd one is limited by "tick" frequency – by default, it's once per second (I'm thinking how to simplify more frequent configs, pg_cron is limited by 1/s).

While 1 and 2 are both sub-ms for PgQue. Consumers just don't see fresh messages until tick happens. Meanwhile, consuming queries is fast.

Hope this helps. Thanks for the question. Will this to README.

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