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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") "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, "+ 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") "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. // 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 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. // evalInstantRollup evaluates instant rollup where ec.Start == ec.End.
func evalInstantRollup(qt *querytracer.Tracer, ec *EvalConfig, funcName string, rf rollupFunc, func evalInstantRollup(qt *querytracer.Tracer, ec *EvalConfig, funcName string, rf rollupFunc,
expr metricsql.Expr, me *metricsql.MetricExpr, iafc *incrementalAggrFuncContext, window int64) ([]*timeseries, error) { 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 { tooBigOffset := func(offset int64) bool {
maxOffset := window / 2 maxOffset := window / 2
if maxOffset > 3600*1000 { if maxOffset > 1800*1000 {
maxOffset = 3600 * 1000 maxOffset = 1800 * 1000
} }
return offset >= maxOffset 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") qt.Printf("do not apply instant rollup optimization because of disabled cache")
return evalAt(qt, timestamp, window) return evalAt(qt, timestamp, window)
} }
if 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) 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) return evalAt(qt, timestamp, window)
} }
switch funcName { switch funcName {