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app/vmselect/promql: optimize quantiles() calculation

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Calculate quantiles in one go instead of calculating each quantile individually
This commit is contained in:
Aliaksandr Valialkin 2021-09-17 12:33:40 +03:00
parent f9910113b5
commit 4ed7548ced
1 changed files with 32 additions and 16 deletions
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48
app/vmselect/promql/aggr.go
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@ -966,30 +966,46 @@ func aggrFuncQuantiles(afa *aggrFuncArg) ([]*timeseries, error) {
return nil, fmt.Errorf("cannot obtain dstLabel: %w", err)
}
phiArgs := args[1 : len(args)-1]
argOrig := args[len(args)-1]
var rvs []*timeseries
phis := make([]float64, len(phiArgs))
for i, phiArg := range phiArgs {
phis, err := getScalar(phiArg, i+1)
phisLocal, err := getScalar(phiArg, i+1)
if err != nil {
return nil, err
}
if len(phis) == 0 {
logger.Panicf("BUG: expecting at least a single sample")
}
phi := phis[0]
afe := newAggrQuantileFunc(phis)
arg := copyTimeseries(argOrig)
tss, err := aggrFuncExt(afe, arg, &afa.ae.Modifier, afa.ae.Limit, false)
if err != nil {
return nil, fmt.Errorf("cannot calculate quantile %g: %w", phi, err)
}
for _, ts := range tss {
ts.MetricName.RemoveTag(dstLabel)
ts.MetricName.AddTag(dstLabel, fmt.Sprintf("%g", phi))
}
rvs = append(rvs, tss...)
phis[i] = phisLocal[0]
}
return rvs, nil
argOrig := args[len(args)-1]
afe := func(tss []*timeseries, modifier *metricsql.ModifierExpr) []*timeseries {
tssDst := make([]*timeseries, len(phiArgs))
for j := range tssDst {
ts := &timeseries{}
ts.CopyFromShallowTimestamps(tss[0])
ts.MetricName.RemoveTag(dstLabel)
ts.MetricName.AddTag(dstLabel, fmt.Sprintf("%g", phis[j]))
tssDst[j] = ts
}
h := histogram.GetFast()
defer histogram.PutFast(h)
var qs []float64
for n := range tss[0].Values {
h.Reset()
for j := range tss {
v := tss[j].Values[n]
if !math.IsNaN(v) {
h.Update(v)
}
}
qs = h.Quantiles(qs[:0], phis)
for j := range tssDst {
tssDst[j].Values[n] = qs[j]
}
}
return tssDst
}
return aggrFuncExt(afe, argOrig, &afa.ae.Modifier, afa.ae.Limit, false)
}
func aggrFuncQuantile(afa *aggrFuncArg) ([]*timeseries, error) {