6 ms·
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 sec
by saberd 5mo ago
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?
- rgbrgb 5mo ago[dead]
- samokhvalov 5mo ago(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.
- hardwaresofton 5mo agoNot the original commenter but this is an excellent answer, thanks for the clear explanation — this is what people continue to come to HN for IMO. Also thanks for all the podcasts and content, always a joy to watch.
- samokhvalov 5mo agothank you!