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Return NaN for histogram_quantile when buckets have 0 observations (#7318)

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Signed-off-by: jberny <f.bernardi89@gmail.com>
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B++ 2020-06-01 10:40:39 +02:00 committed by GitHub
parent 4424d2c3a4
commit d6374ae1b6
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3 changed files with 17 additions and 4 deletions
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4
docs/querying/functions.md
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@ -182,8 +182,8 @@ is assumed to be 0 if the upper bound of that bucket is greater than
bucket. Otherwise, the upper bound of the lowest bucket is returned
for quantiles located in the lowest bucket.
If `b` contains fewer than two buckets, `NaN` is returned. For φ < 0, `-Inf` is
returned. For φ > 1, `+Inf` is returned.
If `b` has 0 observations, `NaN` is returned. If `b` contains fewer than two buckets,
`NaN` is returned. For φ < 0, `-Inf` is returned. For φ > 1, `+Inf` is returned.
## `holt_winters()`

9
promql/quantile.go
View file

@ -61,6 +61,8 @@ type metricWithBuckets struct {
// happening during evaluations of AST functions, we should report those
// explicitly):
//
// If 'buckets' has 0 observations, NaN is returned.
//
// If 'buckets' has fewer than 2 elements, NaN is returned.
//
// If the highest bucket is not +Inf, NaN is returned.
@ -86,8 +88,11 @@ func bucketQuantile(q float64, buckets buckets) float64 {
if len(buckets) < 2 {
return math.NaN()
}
rank := q * buckets[len(buckets)-1].count
observations := buckets[len(buckets)-1].count
if observations == 0 {
return math.NaN()
}
rank := q * observations
b := sort.Search(len(buckets)-1, func(i int) bool { return buckets[i].count >= rank })
if b == len(buckets)-1 {

8
promql/testdata/histograms.test vendored
View file

@ -179,3 +179,11 @@ eval instant at 50m histogram_quantile(0.75, rate(mixed_bucket[5m]))
eval instant at 50m histogram_quantile(1, rate(mixed_bucket[5m]))
{instance="ins1", job="job1"} 0.2
{instance="ins2", job="job1"} NaN
load 5m
empty_bucket{le="0.1", job="job1", instance="ins1"} 0x10
empty_bucket{le="0.2", job="job1", instance="ins1"} 0x10
empty_bucket{le="+Inf", job="job1", instance="ins1"} 0x10
eval instant at 50m histogram_quantile(0.2, rate(empty_bucket[5m]))
{instance="ins1", job="job1"} NaN