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Prometheus: Invest in tests and docs for min interval or min step explanation (#80165)

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* add clearer comment for function def

* update test to reflect change in range for 1w step

* clarify docs

* add more clarity

* add explanation to query options min interval and link to min step

* Update docs/sources/panels-visualizations/query-transform-data/_index.md

Co-authored-by: Isabel <76437239+imatwawana@users.noreply.github.com>

---------

Co-authored-by: Isabel <76437239+imatwawana@users.noreply.github.com>
This commit is contained in:
Brendan O'Handley
2024-01-22 08:44:46 -06:00
committed by GitHub
co-authored by Isabel
parent 639bf3036d
commit 3409e0ea5a
4 changed files with 33 additions and 3 deletions
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pkg/tsdb/prometheus/models/query_test.go
+21 -1
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@@ -739,20 +739,40 @@ func queryContext(json string, timeRange backend.TimeRange, queryInterval time.D
}
}
// AlignTimeRange aligns query range to step and handles the time offset.
// It rounds start and end down to a multiple of step.
// Prometheus caching is dependent on the range being aligned with the step.
// Rounding to the step can significantly change the start and end of the range for larger steps, i.e. a week.
// In rounding the range to a 1w step the range will always start on a Thursday.
func TestAlignTimeRange(t *testing.T) {
type args struct {
t time.Time
step time.Duration
offset int64
}
var monday int64 = 1704672000
var thursday int64 = 1704326400
var one_week_min_step = 604800 * time.Second
tests := []struct {
name string
args args
want time.Time
}{
{name: "second step", args: args{t: time.Unix(1664816826, 0), step: 10 * time.Second, offset: 0}, want: time.Unix(1664816820, 0).UTC()},
{
name: "second step",
args: args{t: time.Unix(1664816826, 0), step: 10 * time.Second, offset: 0},
want: time.Unix(1664816820, 0).UTC(),
},
{name: "millisecond step", args: args{t: time.Unix(1664816825, 5*int64(time.Millisecond)), step: 10 * time.Millisecond, offset: 0}, want: time.Unix(1664816825, 0).UTC()},
{name: "second step with offset", args: args{t: time.Unix(1664816825, 5*int64(time.Millisecond)), step: 2 * time.Second, offset: -3}, want: time.Unix(1664816825, 0).UTC()},
// we may not want this functionality in the future but if we change this we break Prometheus caching.
{
name: "1w step with range date of Monday that changes the range to a Thursday.",
args: args{t: time.Unix(monday, 0), step: one_week_min_step, offset: 0},
want: time.Unix(thursday, 0).UTC(),
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {