update documentation

app/vmselect/promql/exec_test.go

@@ -8801,6 +8801,17 @@ func TestExecSuccess(t *testing.T) {
 		resultExpected := []netstorage.Result{r}
 		f(q, resultExpected)
 	})
+	t.Run(`range()`, func(t *testing.T) {
+		t.Parallel()
+		q := `range()`
+		r := netstorage.Result{
+			MetricName: metricNameExpected,
+			Values:     []float64{1000, 1000, 1000, 1000, 1000, 1000},
+			Timestamps: timestampsExpected,
+		}
+		resultExpected := []netstorage.Result{r}
+		f(q, resultExpected)
+	})
 	t.Run(`step()`, func(t *testing.T) {
 		t.Parallel()
 		q := `time() / step()`

app/vmselect/promql/transform.go

@@ -90,6 +90,7 @@ var transformFuncs = map[string]transformFunc{
 	"rand":                       newTransformRand(newRandFloat64),
 	"rand_exponential":           newTransformRand(newRandExpFloat64),
 	"rand_normal":                newTransformRand(newRandNormFloat64),
+	"range":                      newTransformFuncZeroArgs(transformRange),
 	"range_avg":                  newTransformFuncRange(runningAvg),
 	"range_first":                transformRangeFirst,
 	"range_last":                 transformRangeLast,
@@ -2808,6 +2809,10 @@ func transformEnd(tfa *transformFuncArg) float64 {
 	return float64(tfa.ec.End) / 1e3
 }
 
+func transformRange(tfa *transformFuncArg) float64 {
+	return float64(tfa.ec.End-tfa.ec.Start) / 1e3
+}
+
 // copyTimeseries returns a copy of tss.
 func copyTimeseries(tss []*timeseries) []*timeseries {
 	rvs := make([]*timeseries, len(tss))

docs/victoriametrics/MetricsQL.md

@@ -1357,7 +1357,7 @@ by replacing all the values bigger or equal to 30 with 40.
 `end()` is a [transform function](#transform-functions), which returns the unix timestamp in seconds for the last point.
 It is known as `end` query arg passed to [/api/v1/query_range](https://docs.victoriametrics.com/victoriametrics/keyconcepts/#range-query).
 
-See also [start](#start), [time](#time) and [now](#now).
+See also [start](#start), [time](#time), [now](#now) and [range](#range).
 
 #### exp
 
@@ -1575,6 +1575,12 @@ with [normal distribution](https://en.wikipedia.org/wiki/Normal_distribution). O
 
 See also [rand](#rand) and [rand_exponential](#rand_exponential).
 
+#### range
+
+`range()` is a [transform function](#transform-functions), which returns the range duration of the current query range evaluation in seconds and is equivalent to `end() - start()`.
+
+See also [start](#start) and [end](#end).
+
 #### range_avg
 
 `range_avg(q)` is a [transform function](#transform-functions), which calculates the avg value across points per each time series returned by `q`.
@@ -1789,7 +1795,7 @@ This function is supported by PromQL.
 
 It is known as `start` query arg passed to [/api/v1/query_range](https://docs.victoriametrics.com/victoriametrics/keyconcepts/#range-query).
 
-See also [end](#end), [time](#time) and [now](#now).
+See also [end](#end), [time](#time), [now](#now) and [range](#range).
 
 #### step
 

docs/victoriametrics/changelog/CHANGELOG.md

@@ -29,6 +29,7 @@ See also [LTS releases](https://docs.victoriametrics.com/victoriametrics/lts-rel
 * FEATURE: [vmalert](https://docs.victoriametrics.com/victoriametrics/vmalert/): support `match[]=<label_selector>` query parameters in `/api/v1/rules` and `/api/v1/alerts` APIs to return only the rules that have configured labels satisfying the provided label selectors. See [11020](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/11020).
 * FEATURE: [vmagent](https://docs.victoriametrics.com/victoriametrics/vmagent/), [vmsingle](https://docs.victoriametrics.com/victoriametrics/single-server-victoriametrics/) and `vminsert` in [VictoriaMetrics cluster](https://docs.victoriametrics.com/victoriametrics/cluster-victoriametrics/): add `-opentelemetry.promoteAllResourceAttributes` and `-opentelemetry.promoteScopeMetadata` command-line flags to allow managing label promotion for resource attributes and OTel scope metadata. See [OpenTelemetry](https://docs.victoriametrics.com/victoriametrics/integrations/opentelemetry/) docs and [#10931](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/10931).
 * FEATURE: [vmctl](https://docs.victoriametrics.com/vmctl/): add the ability to migrate data from Mimir object storage to VictoriaMetrics. See [#7717](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/7717). 
+* FEATURE: [MetricsQL](https://docs.victoriametrics.com/victoriametrics/metricsql/): support `range()` function, which returns the range duration of the current query range evaluation in seconds. See [#11028](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/11028).
 
 * BUGFIX: [vmalert](https://docs.victoriametrics.com/victoriametrics/vmalert/): fix the `Notifiers` page in web UI appearing blank despite the API returning notifier data correctly. See [#11035](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/11035).
 * BUGFIX: [vmalert](https://docs.victoriametrics.com/victoriametrics/vmalert/): reset the group evaluation timestamp if it exceeds the current host time. Previously, vmalert could use future timestamps for evaluations if the system clock was shifted backward. See [#10985](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/10985).