native histograms: histogram_count and histogram_sum wrong result #16681
Description
What did you do?
Originally reported on Mimir 2.16 in grafana/mimir#11148
Under some circumstances histogram_count and histogram_sum produce a result different from what count and sum the underlying native histogram has.
I've managed to reproduce the issue eventually by using the same (or very similar) input histograms that we see at the user.
See PR
What did you expect to see?
The native histogram count should be the same between
sum(rate(series_1[10m]))
and
histogram_count(sum(rate(series_1[10m])))
What did you see instead? Under which circumstances?
Instead:
-- FAIL: TestInconsistentHistogramCount (0.01s)
/home/krajo/go/github.com/prometheus/prometheus/promql/engine_test.go:4293:
Error Trace: /home/krajo/go/github.com/prometheus/prometheus/promql/engine_test.go:4293
Error: Not equal:
expected: 0.0068000000000000005
actual : 0
Test: TestInconsistentHistogramCount
Messages: histogram_count function should return the same count as the histogram itself
System information
unit test
Prometheus version
main 8fd46f74aa0155e4d5aa30654f9c02e564e03743
Prometheus configuration file
N/AAlertmanager version
N/A
Alertmanager configuration file
N/ALogs
N/A