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app/vmselect/promql: reduce the minimum lookbehind window for enabling SLO/SLI optimizations from 24 hours to 6 hours

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This reduction is based on production testing.

Also expose -search.minWindowForInstantRollupOptimization command-line flag, so users could fine-tune this arg for their needs
This commit is contained in:
Aliaksandr Valialkin 2023-11-01 20:16:15 +01:00
parent f59dda3223
commit 4497a08e3d
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GPG key ID: A72BEC6CD3D0DED1
1 changed files with 7 additions and 8 deletions
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15
app/vmselect/promql/eval.go
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@ -41,6 +41,8 @@ var (
"See also -search.logSlowQueryDuration and -search.maxMemoryPerQuery")
noStaleMarkers = flag.Bool("search.noStaleMarkers", false, "Set this flag to true if the database doesn't contain Prometheus stale markers, "+
"so there is no need in spending additional CPU time on its handling. Staleness markers may exist only in data obtained from Prometheus scrape targets")
minWindowForInstantRollupOptimization = flag.Duration("search.minWindowForInstantRollupOptimization", 6*time.Hour, "Enable optimization for queries to /api/v1/query "+
"(aka instant queries), which contain rollup functions with lookbehind window exceeding the given value")
)
// The minimum number of points per timeseries for enabling time rounding.
@ -1056,10 +1058,6 @@ func removeNanValues(dstValues []float64, dstTimestamps []int64, values []float6
return dstValues, dstTimestamps
}
// minWindowForInstantRollupOptimization is the minimum lookbehind window in milliseconds
// for enabling smart caching of instant rollup function results.
const minWindowForInstantRollupOptimization = 24 * 3600 * 1000
// evalInstantRollup evaluates instant rollup where ec.Start == ec.End.
func evalInstantRollup(qt *querytracer.Tracer, ec *EvalConfig, funcName string, rf rollupFunc,
expr metricsql.Expr, me *metricsql.MetricExpr, iafc *incrementalAggrFuncContext, window int64) ([]*timeseries, error) {
@ -1081,8 +1079,8 @@ func evalInstantRollup(qt *querytracer.Tracer, ec *EvalConfig, funcName string,
}
tooBigOffset := func(offset int64) bool {
maxOffset := window / 2
if maxOffset > 3600*1000 {
maxOffset = 3600 * 1000
if maxOffset > 1800*1000 {
maxOffset = 1800 * 1000
}
return offset >= maxOffset
}
@ -1091,8 +1089,9 @@ func evalInstantRollup(qt *querytracer.Tracer, ec *EvalConfig, funcName string,
qt.Printf("do not apply instant rollup optimization because of disabled cache")
return evalAt(qt, timestamp, window)
}
if window < minWindowForInstantRollupOptimization {
qt.Printf("do not apply instant rollup optimization because of too small window=%d; must be equal or bigger than %d", window, minWindowForInstantRollupOptimization)
if window < minWindowForInstantRollupOptimization.Milliseconds() {
qt.Printf("do not apply instant rollup optimization because of too small window=%d; must be equal or bigger than %d",
window, minWindowForInstantRollupOptimization.Milliseconds())
return evalAt(qt, timestamp, window)
}
switch funcName {