{app/vmselect,docs}: support share_eq_over_time#4441 (#4725)

https://github.com/VictoriaMetrics/VictoriaMetrics/issues/4441

Co-authored-by: wangm <wangmm@tuya.com>

app/vmselect/promql/exec_test.go

@@ -5826,6 +5826,17 @@ func TestExecSuccess(t *testing.T) {
 		resultExpected := []netstorage.Result{r}
 		f(q, resultExpected)
 	})
+	t.Run(`share_eq_over_time`, func(t *testing.T) {
+		t.Parallel()
+		q := `share_eq_over_time(round(5*rand(0))[200s:10s], 1)`
+		r := netstorage.Result{
+			MetricName: metricNameExpected,
+			Values:     []float64{0.1, 0.2, 0.25, 0.1, 0.3, 0.3},
+			Timestamps: timestampsExpected,
+		}
+		resultExpected := []netstorage.Result{r}
+		f(q, resultExpected)
+	})
 	t.Run(`count_gt_over_time`, func(t *testing.T) {
 		t.Parallel()
 		q := `count_gt_over_time(rand(0)[200s:10s], 0.7)`

app/vmselect/promql/rollup.go

@@ -78,6 +78,7 @@ var rollupFuncs = map[string]newRollupFunc{
 	"scrape_interval":         newRollupFuncOneArg(rollupScrapeInterval),
 	"share_gt_over_time":      newRollupShareGT,
 	"share_le_over_time":      newRollupShareLE,
+	"share_eq_over_time":      newRollupShareEQ,
 	"stale_samples_over_time": newRollupFuncOneArg(rollupStaleSamples),
 	"stddev_over_time":        newRollupFuncOneArg(rollupStddev),
 	"stdvar_over_time":        newRollupFuncOneArg(rollupStdvar),
@@ -1106,6 +1107,10 @@ func countFilterGT(values []float64, gt float64) int {
 	return n
 }
 
+func newRollupShareEQ(args []interface{}) (rollupFunc, error) {
+	return newRollupShareFilter(args, countFilterEQ)
+}
+
 func countFilterEQ(values []float64, eq float64) int {
 	n := 0
 	for _, v := range values {

app/vmselect/promql/rollup_test.go

@@ -261,6 +261,25 @@ func TestRollupShareGTOverTime(t *testing.T) {
 	f(1000, 0)
 }
 
+func TestRollupShareEQOverTime(t *testing.T) {
+	f := func(eq, vExpected float64) {
+		t.Helper()
+		eqs := []*timeseries{{
+			Values:     []float64{eq},
+			Timestamps: []int64{123},
+		}}
+		var me metricsql.MetricExpr
+		args := []interface{}{&metricsql.RollupExpr{Expr: &me}, eqs}
+		testRollupFunc(t, "share_eq_over_time", args, &me, vExpected)
+	}
+
+	f(-123, 0)
+	f(34, 0.3333333333333333)
+	f(44, 0.16666666666666666)
+	f(123, 0.08333333333333333)
+	f(1000, 0)
+}
+
 func TestRollupCountLEOverTime(t *testing.T) {
 	f := func(le, vExpected float64) {
 		t.Helper()

docs/MetricsQL.md

@@ -744,6 +744,14 @@ Metric names are stripped from the resulting rollups. Add [keep_metric_names](#k
 
 See also [share_gt_over_time](#share_gt_over_time).
 
+#### share_eq_over_time
+
+`share_eq_over_time(series_selector[d], eq)` is a [rollup function](#rollup-functions), which returns share (in the range `[0...1]`) of raw samples
+on the given lookbehind window `d`, which are equal to `eq`. It is calculated independently per each time series returned
+from the given [series_selector](https://docs.victoriametrics.com/keyConcepts.html#filtering).
+
+Metric names are stripped from the resulting rollups. Add [keep_metric_names](#keep_metric_names) modifier in order to keep metric names.
+
 #### stale_samples_over_time
 
 `stale_samples_over_time(series_selector[d])` is a [rollup function](#rollup-functions), which calculates the number