docs/CHANGELOG.md: update the description of the optimization for SLO/SLI-like queries according to latest changes

See commits 4497a08e3d and 92826b0b4a

README.md

@@ -1264,6 +1264,9 @@ Below is the output for `/path/to/vmselect -help`:
      The maximum number of CPU cores a single query can use. The default value should work good for most cases. The flag can be set to lower values for improving performance of big number of concurrently executed queries. The flag can be set to bigger values for improving performance of heavy queries, which scan big number of time series (>10K) and/or big number of samples (>100M). There is no sense in setting this flag to values bigger than the number of CPU cores available on the system (default 4)
   -search.minStalenessInterval duration
      The minimum interval for staleness calculations. This flag could be useful for removing gaps on graphs generated from time series with irregular intervals between samples. See also '-search.maxStalenessInterval'
+  -search.minWindowForInstantRollupOptimization value
+     Enable cache-based optimization for repeated queries to /api/v1/query (aka instant queries), which contain rollup functions with lookbehind window exceeding the given value
+     The following optional suffixes are supported: s (second), m (minute), h (hour), d (day), w (week), y (year). If suffix isn't set, then the duration is counted in months (default 6h)
   -search.noStaleMarkers
      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
   -search.queryStats.lastQueriesCount int

app/vmselect/promql/eval.go

@@ -42,8 +42,8 @@ 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")
+	minWindowForInstantRollupOptimization = flagutil.NewDuration("search.minWindowForInstantRollupOptimization", "6h", "Enable cache-based optimization for repeated 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.

docs/CHANGELOG.md

@@ -33,13 +33,17 @@ The sandbox cluster installation is running under the constant load generated by
 
 * SECURITY: upgrade Go builder from Go1.21.1 to Go1.21.3. See [the list of issues addressed in Go1.21.2](https://github.com/golang/go/issues?q=milestone%3AGo1.21.2+label%3ACherryPickApproved) and [the list of issues addressed in Go1.21.3](https://github.com/golang/go/issues?q=milestone%3AGo1.21.3+label%3ACherryPickApproved).
 
-* FEATURE: `vmselect`: improve performance for repeated [instant queries](https://docs.victoriametrics.com/keyConcepts.html#instant-query) if they contain one of the following [rollup functions](https://docs.victoriametrics.com/MetricsQL.html#rollup-functions) with lookbehind window in square brackets bigger or equal to 1 day:
-  - [sum_over_time](https://docs.victoriametrics.com/MetricsQL.html#sum_over_time)
-  - [count_over_time](https://docs.victoriametrics.com/MetricsQL.html#count_over_time)
+* FEATURE: `vmselect`: improve performance for repeated [instant queries](https://docs.victoriametrics.com/keyConcepts.html#instant-query) if they contain one of the following [rollup functions](https://docs.victoriametrics.com/MetricsQL.html#rollup-functions):
   - [avg_over_time](https://docs.victoriametrics.com/MetricsQL.html#avg_over_time)
+  - [sum_over_time](https://docs.victoriametrics.com/MetricsQL.html#sum_over_time)
+  - [count_eq_over_time](https://docs.victoriametrics.com/MetricsQL.html#count_eq_over_time)
+  - [count_gt_over_time](https://docs.victoriametrics.com/MetricsQL.html#count_gt_over_time)
+  - [count_le_over_time](https://docs.victoriametrics.com/MetricsQL.html#count_le_over_time)
+  - [count_ne_over_time](https://docs.victoriametrics.com/MetricsQL.html#count_ne_over_time)
+  - [count_over_time](https://docs.victoriametrics.com/MetricsQL.html#count_over_time)
   - [increase](https://docs.victoriametrics.com/MetricsQL.html#increase)
   - [rate](https://docs.victoriametrics.com/MetricsQL.html#rate)
-  These functions are usually used in SLO/SLI queries such as `avg_over_time(up[30d])` or `sum(rate(http_request_errors_total[3d])) / sum(rate(http_requests_total[3d]))`.
+  The optimization is enabled when these functions contain lookbehind window in square brackets bigger or equal to `6h` (the threshold can be changed via `-search.minWindowForInstantRollupOptimization` command-line flag). The optimization improves performance for SLO/SLI-like queries such as `avg_over_time(up[30d])` or `sum(rate(http_request_errors_total[3d])) / sum(rate(http_requests_total[3d]))`, which can be generated by [sloth](https://github.com/slok/sloth) or similar projects.
 * FEATURE: `vmselect`: improve query performance on systems with big number of CPU cores (`>=32`). Add `-search.maxWorkersPerQuery` command-line flag, which can be used for fine-tuning query performance on systems with big number of CPU cores. See [this pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5195).
 * FEATURE: `vmselect`: expose `vm_memory_intensive_queries_total` counter metric which gets increased each time `-search.logQueryMemoryUsage` memory limit is exceeded by a query. This metric should help to identify expensive and heavy queries without inspecting the logs.
 * FEATURE: [MetricsQL](https://docs.victoriametrics.com/MetricsQL.html): add [drop_empty_series()](https://docs.victoriametrics.com/MetricsQL.html#drop_empty_series) function, which can be used for filtering out empty series before performing additional calculations as shown in [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5071).

docs/Cluster-VictoriaMetrics.md

@@ -1275,6 +1275,9 @@ Below is the output for `/path/to/vmselect -help`:
      The maximum number of CPU cores a single query can use. The default value should work good for most cases. The flag can be set to lower values for improving performance of big number of concurrently executed queries. The flag can be set to bigger values for improving performance of heavy queries, which scan big number of time series (>10K) and/or big number of samples (>100M). There is no sense in setting this flag to values bigger than the number of CPU cores available on the system (default 4)
   -search.minStalenessInterval duration
      The minimum interval for staleness calculations. This flag could be useful for removing gaps on graphs generated from time series with irregular intervals between samples. See also '-search.maxStalenessInterval'
+  -search.minWindowForInstantRollupOptimization value
+     Enable cache-based optimization for repeated queries to /api/v1/query (aka instant queries), which contain rollup functions with lookbehind window exceeding the given value
+     The following optional suffixes are supported: s (second), m (minute), h (hour), d (day), w (week), y (year). If suffix isn't set, then the duration is counted in months (default 6h)
   -search.noStaleMarkers
      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
   -search.queryStats.lastQueriesCount int

docs/README.md

@@ -2870,6 +2870,9 @@ Pass `-help` to VictoriaMetrics in order to see the list of supported command-li
      The maximum number of CPU cores a single query can use. The default value should work good for most cases. The flag can be set to lower values for improving performance of big number of concurrently executed queries. The flag can be set to bigger values for improving performance of heavy queries, which scan big number of time series (>10K) and/or big number of samples (>100M). There is no sense in setting this flag to values bigger than the number of CPU cores available on the system (default 4)
   -search.minStalenessInterval duration
      The minimum interval for staleness calculations. This flag could be useful for removing gaps on graphs generated from time series with irregular intervals between samples. See also '-search.maxStalenessInterval'
+  -search.minWindowForInstantRollupOptimization value
+     Enable cache-based optimization for repeated queries to /api/v1/query (aka instant queries), which contain rollup functions with lookbehind window exceeding the given value
+     The following optional suffixes are supported: s (second), m (minute), h (hour), d (day), w (week), y (year). If suffix isn't set, then the duration is counted in months (default 6h)
   -search.noStaleMarkers
      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
   -search.queryStats.lastQueriesCount int

docs/Single-server-VictoriaMetrics.md

@@ -2878,6 +2878,9 @@ Pass `-help` to VictoriaMetrics in order to see the list of supported command-li
      The maximum number of CPU cores a single query can use. The default value should work good for most cases. The flag can be set to lower values for improving performance of big number of concurrently executed queries. The flag can be set to bigger values for improving performance of heavy queries, which scan big number of time series (>10K) and/or big number of samples (>100M). There is no sense in setting this flag to values bigger than the number of CPU cores available on the system (default 4)
   -search.minStalenessInterval duration
      The minimum interval for staleness calculations. This flag could be useful for removing gaps on graphs generated from time series with irregular intervals between samples. See also '-search.maxStalenessInterval'
+  -search.minWindowForInstantRollupOptimization value
+     Enable cache-based optimization for repeated queries to /api/v1/query (aka instant queries), which contain rollup functions with lookbehind window exceeding the given value
+     The following optional suffixes are supported: s (second), m (minute), h (hour), d (day), w (week), y (year). If suffix isn't set, then the duration is counted in months (default 6h)
   -search.noStaleMarkers
      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
   -search.queryStats.lastQueriesCount int

lib/flagutil/duration.go

@@ -14,7 +14,8 @@ import (
 //
 // DefaultValue is in months.
 func NewDuration(name string, defaultValue string, description string) *Duration {
-	description += "\nThe following optional suffixes are supported: h (hour), d (day), w (week), y (year). If suffix isn't set, then the duration is counted in months"
+	description += "\nThe following optional suffixes are supported: s (second), m (minute), h (hour), d (day), w (week), y (year). "+
+		"If suffix isn't set, then the duration is counted in months"
 	d := &Duration{}
 	if err := d.Set(defaultValue); err != nil {
 		panic(fmt.Sprintf("BUG: can not parse default value %s for flag %s", defaultValue, name))