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vmselect/rollup: rm workaround for slow-changing counters (#3163)

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The workaround was introduced to fix https://github.com/VictoriaMetrics/VictoriaMetrics/issues/962.
However, it didn't prove itself useful. Instead, it is recommended using `increase_pure` function.

Removing the workaround makes VM to produce accurate results when calculating
`delta` or `increase` functions over slow-changing counters with vary intervals
between data points.

Signed-off-by: hagen1778 <roman@victoriametrics.com>

Signed-off-by: hagen1778 <roman@victoriametrics.com>
This commit is contained in:
Roman Khavronenko 2022-09-26 14:33:25 +02:00 committed by Aliaksandr Valialkin
parent dca89c7d2f
commit 5839112cda
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GPG key ID: A72BEC6CD3D0DED1
2 changed files with 6 additions and 15 deletions
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10
app/vmselect/promql/rollup.go
View file

@ -1485,11 +1485,8 @@ func rollupDelta(rfa *rollupFuncArg) float64 {
// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/894
return values[len(values)-1] - rfa.realPrevValue
}
// Assume that the previous non-existing value was 0 only in the following cases:
//
// - If the delta with the next value equals to 0.
// This is the case for slow-changing counter - see https://github.com/VictoriaMetrics/VictoriaMetrics/issues/962
// - If the first value doesn't exceed too much the delta with the next value.
// Assume that the previous non-existing value was 0
// only if the first value doesn't exceed too much the delta with the next value.
//
// This should prevent from improper increase() results for os-level counters
// such as cpu time or bytes sent over the network interface.
@ -1503,9 +1500,6 @@ func rollupDelta(rfa *rollupFuncArg) float64 {
} else if !math.IsNaN(rfa.realNextValue) {
d = rfa.realNextValue - values[0]
}
if d == 0 {
d = 10
}
if math.Abs(values[0]) < 10*(math.Abs(d)+1) {
prevValue = 0
} else {

11
app/vmselect/promql/rollup_test.go
View file

@ -1383,19 +1383,16 @@ func TestRollupDelta(t *testing.T) {
// Small initial value
f(nan, nan, nan, []float64{1}, 1)
f(nan, nan, nan, []float64{10}, 10)
f(nan, nan, nan, []float64{100}, 100)
f(nan, nan, nan, []float64{10}, 0)
f(nan, nan, nan, []float64{100}, 0)
f(nan, nan, nan, []float64{1, 2, 3}, 3)
f(1, nan, nan, []float64{1, 2, 3}, 2)
f(nan, nan, nan, []float64{5, 6, 8}, 8)
f(2, nan, nan, []float64{5, 6, 8}, 6)
// Moderate initial value with zero delta after that.
// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/962
f(nan, nan, nan, []float64{100}, 100)
f(nan, nan, nan, []float64{100, 100}, 100)
f(nan, nan, nan, []float64{100, 100}, 0)
// Big initial value with with zero delta after that.
// Big initial value with zero delta after that.
f(nan, nan, nan, []float64{1000}, 0)
f(nan, nan, nan, []float64{1000, 1000}, 0)