From 0fa70e0f6c129e121669ee9823f22d4e4993966d Mon Sep 17 00:00:00 2001 From: beorn7 Date: Wed, 3 Sep 2025 19:21:21 +0200 Subject: [PATCH] promql: Use `HistogramStatsIterator` more often The current code stops the walk after we have found the first relevant function. However, in expressions with multiple legs, we will then use the `HistogramStatsIterator` at most once. This change should make sure we explore all legs. The added tests make sure we are not using `HistogramStatsIterator` where we shouldn't (but the opposite can only be seen in a benchmark or with a more explicit test). Signed-off-by: beorn7 --- promql/engine.go | 2 +- .../promqltest/testdata/native_histograms.test | 17 +++++++++++++++++ 2 files changed, 18 insertions(+), 1 deletion(-) diff --git a/promql/engine.go b/promql/engine.go index 91257eae37..edafe4fd43 100644 --- a/promql/engine.go +++ b/promql/engine.go @@ -3920,7 +3920,7 @@ func detectHistogramStatsDecoding(expr parser.Expr) { break pathLoop } } - return errors.New("stop") + return nil }) } diff --git a/promql/promqltest/testdata/native_histograms.test b/promql/promqltest/testdata/native_histograms.test index 83933e1e7f..f0c510bd50 100644 --- a/promql/promqltest/testdata/native_histograms.test +++ b/promql/promqltest/testdata/native_histograms.test @@ -1660,3 +1660,20 @@ eval instant at 30s histogram_count(avg(reset)) eval instant at 5m histogram_count(rate(reset{timing="late"}[5m])) expect no_warn {timing="late"} 0.0175 + +clear + +# Test edge cases of HistogramStatsIterator detection. +# We access the same series multiple times within the same expression, +# once with and once without HistogramStatsIterator. The results here +# at least prove that we do not use HistogramStatsIterator where we +# should not. +load 1m + histogram {{schema:0 count:10 sum:50 counter_reset_hint:gauge buckets:[1 2 3 4]}} + +eval instant at 1m histogram_count(histogram unless histogram_quantile(0.5, histogram) < 3) + {} 10 + +eval instant at 1m histogram_quantile(0.5, histogram unless histogram_count(histogram) == 0) + {} 3.1748021039363987 +