Prometheus: How does the rate function calculate per second rate when scrape interval is longer?

Question

From Prometheus documentation rate function does the following:

rate(v range-vector) calculates the per-second average rate of increase of the time series in the range vector.

How is that possible when scrape interval is longer like 15 seconds ? I mean how does Prometheus estimate "per-second" value when the data points are at least 15 seconds far away? I assume that the change is estimated to be uniform in the scrape interval but want to be sure.

Answer 1

I assume that the change is estimated to be uniform in the scrape interval but want to be sure.

Yes, that's the case. The units of the return value are per-second.