app/vmselect/promql: properly return q1 series from q1 ifnot q2 when q2 returns nothing

app/vmselect/promql/binary_op.go

@@ -36,9 +36,9 @@ var binaryOpFuncs = map[string]binaryOpFunc{
 	"unless": binaryOpUnless,
 
 	// New ops
-	"if":      newBinaryOpArithFunc(binaryop.If),
-	"ifnot":   newBinaryOpArithFunc(binaryop.Ifnot),
-	"default": newBinaryOpArithFunc(binaryop.Default),
+	"if":      binaryOpIf,
+	"ifnot":   binaryOpIfnot,
+	"default": binaryOpDefault,
 }
 
 func getBinaryOpFunc(op string) binaryOpFunc {
@@ -86,17 +86,6 @@ func newBinaryOpFunc(bf func(left, right float64, isBool bool) float64) binaryOp
 		right := bfa.right
 		op := bfa.be.Op
 		switch true {
-		case op == "ifnot":
-			left = removeEmptySeries(left)
-			// Do not remove empty series on the right side,
-			// so the left-side series could be matched against them.
-		case op == "default":
-			// Do not remove empty series on the left and the right side,
-			// since this may lead to missing result:
-			// - if empty time series are removed on the left side,
-			// then they won't be substituted by time series from the right side.
-			// - if empty time series are removed on the right side,
-			// then this may result in missing time series from the left side.
 		case metricsql.IsBinaryOpCmp(op):
 			// Do not remove empty series for comparison operations,
 			// since this may lead to missing result.
@@ -136,7 +125,7 @@ func newBinaryOpFunc(bf func(left, right float64, isBool bool) float64) binaryOp
 
 func adjustBinaryOpTags(be *metricsql.BinaryOpExpr, left, right []*timeseries) ([]*timeseries, []*timeseries, []*timeseries, error) {
 	if len(be.GroupModifier.Op) == 0 && len(be.JoinModifier.Op) == 0 {
-		if isScalar(left) && be.Op != "default" && be.Op != "if" && be.Op != "ifnot" {
+		if isScalar(left) {
 			// Fast path: `scalar op vector`
 			rvsLeft := make([]*timeseries, len(right))
 			tsLeft := left[0]
@@ -324,14 +313,23 @@ func resetMetricGroupIfRequired(be *metricsql.BinaryOpExpr, ts *timeseries) {
 		// Do not reset MetricGroup for non-boolean `compare` binary ops like Prometheus does.
 		return
 	}
-	switch be.Op {
-	case "default", "if", "ifnot":
-		// Do not reset MetricGroup for these ops.
-		return
-	}
 	ts.MetricName.ResetMetricGroup()
 }
 
+func binaryOpIf(bfa *binaryOpFuncArg) ([]*timeseries, error) {
+	mLeft, mRight := createTimeseriesMapByTagSet(bfa.be, bfa.left, bfa.right)
+	var rvs []*timeseries
+	for k, tssLeft := range mLeft {
+		tssRight := seriesByKey(mRight, k)
+		if tssRight == nil {
+			continue
+		}
+		tssLeft = addRightNaNsToLeft(tssLeft, tssRight)
+		rvs = append(rvs, tssLeft...)
+	}
+	return rvs, nil
+}
+
 func binaryOpAnd(bfa *binaryOpFuncArg) ([]*timeseries, error) {
 	mLeft, mRight := createTimeseriesMapByTagSet(bfa.be, bfa.left, bfa.right)
 	var rvs []*timeseries
@@ -340,7 +338,13 @@ func binaryOpAnd(bfa *binaryOpFuncArg) ([]*timeseries, error) {
 		if tssLeft == nil {
 			continue
 		}
-		// Add gaps to tssLeft if there are gaps at tssRight.
+		tssLeft = addRightNaNsToLeft(tssLeft, tssRight)
+		rvs = append(rvs, tssLeft...)
+	}
+	return rvs, nil
+}
+
+func addRightNaNsToLeft(tssLeft, tssRight []*timeseries) []*timeseries {
 	for _, tsLeft := range tssLeft {
 		valuesLeft := tsLeft.Values
 		for i := range valuesLeft {
@@ -356,8 +360,25 @@ func binaryOpAnd(bfa *binaryOpFuncArg) ([]*timeseries, error) {
 			}
 		}
 	}
-		tssLeft = removeEmptySeries(tssLeft)
+	return removeEmptySeries(tssLeft)
+}
+
+func binaryOpDefault(bfa *binaryOpFuncArg) ([]*timeseries, error) {
+	mLeft, mRight := createTimeseriesMapByTagSet(bfa.be, bfa.left, bfa.right)
+	var rvs []*timeseries
+	if len(mLeft) == 0 {
+		for _, tss := range mRight {
+			rvs = append(rvs, tss...)
+		}
+		return rvs, nil
+	}
+	for k, tssLeft := range mLeft {
 		rvs = append(rvs, tssLeft...)
+		tssRight := seriesByKey(mRight, k)
+		if tssRight == nil {
+			continue
+		}
+		fillLeftNaNsWithRightValues(tssLeft, tssRight)
 	}
 	return rvs, nil
 }
@@ -374,6 +395,12 @@ func binaryOpOr(bfa *binaryOpFuncArg) ([]*timeseries, error) {
 			rvs = append(rvs, tssRight...)
 			continue
 		}
+		fillLeftNaNsWithRightValues(tssLeft, tssRight)
+	}
+	return rvs, nil
+}
+
+func fillLeftNaNsWithRightValues(tssLeft, tssRight []*timeseries) {
 	// Fill gaps in tssLeft with values from tssRight as Prometheus does.
 	// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/552
 	for _, tsLeft := range tssLeft {
@@ -392,6 +419,19 @@ func binaryOpOr(bfa *binaryOpFuncArg) ([]*timeseries, error) {
 		}
 	}
 }
+
+func binaryOpIfnot(bfa *binaryOpFuncArg) ([]*timeseries, error) {
+	mLeft, mRight := createTimeseriesMapByTagSet(bfa.be, bfa.left, bfa.right)
+	var rvs []*timeseries
+	for k, tssLeft := range mLeft {
+		tssRight := seriesByKey(mRight, k)
+		if tssRight == nil {
+			rvs = append(rvs, tssLeft...)
+			continue
+		}
+		tssLeft = addLeftNaNsIfNoRightNaNs(tssLeft, tssRight)
+		rvs = append(rvs, tssLeft...)
+	}
 	return rvs, nil
 }
 
@@ -404,7 +444,13 @@ func binaryOpUnless(bfa *binaryOpFuncArg) ([]*timeseries, error) {
 			rvs = append(rvs, tssLeft...)
 			continue
 		}
-		// Add gaps to tssLeft if the are no gaps at tssRight.
+		tssLeft = addLeftNaNsIfNoRightNaNs(tssLeft, tssRight)
+		rvs = append(rvs, tssLeft...)
+	}
+	return rvs, nil
+}
+
+func addLeftNaNsIfNoRightNaNs(tssLeft, tssRight []*timeseries) []*timeseries {
 	for _, tsLeft := range tssLeft {
 		valuesLeft := tsLeft.Values
 		for i := range valuesLeft {
@@ -416,10 +462,24 @@ func binaryOpUnless(bfa *binaryOpFuncArg) ([]*timeseries, error) {
 			}
 		}
 	}
-		tssLeft = removeEmptySeries(tssLeft)
-		rvs = append(rvs, tssLeft...)
+	return removeEmptySeries(tssLeft)
 }
-	return rvs, nil
+
+func seriesByKey(m map[string][]*timeseries, key string) []*timeseries {
+	tss := m[key]
+	if tss != nil {
+		return tss
+	}
+	if len(m) != 1 {
+		return nil
+	}
+	for _, tss := range m {
+		if isScalar(tss) {
+			return tss
+		}
+		return nil
+	}
+	return nil
 }
 
 func createTimeseriesMapByTagSet(be *metricsql.BinaryOpExpr, left, right []*timeseries) (map[string][]*timeseries, map[string][]*timeseries) {

app/vmselect/promql/exec_test.go

@@ -2813,7 +2813,12 @@ func TestExecSuccess(t *testing.T) {
 	t.Run(`scalar default vector1`, func(t *testing.T) {
 		t.Parallel()
 		q := `time() > 1400 default label_set(123, "foo", "bar")`
-		resultExpected := []netstorage.Result{}
+		r := netstorage.Result{
+			MetricName: metricNameExpected,
+			Values:     []float64{nan, nan, nan, 1600, 1800, 2000},
+			Timestamps: timestampsExpected,
+		}
+		resultExpected := []netstorage.Result{r}
 		f(q, resultExpected)
 	})
 	t.Run(`scalar default vector2`, func(t *testing.T) {
@@ -6102,7 +6107,18 @@ func TestExecSuccess(t *testing.T) {
 	t.Run(`ifnot-no-matching-timeseries`, func(t *testing.T) {
 		t.Parallel()
 		q := `label_set(time(), "foo", "bar") ifnot label_set(time() > 1400, "x", "y")`
-		resultExpected := []netstorage.Result{}
+		r := netstorage.Result{
+			MetricName: metricNameExpected,
+			Values:     []float64{1000, 1200, 1400, 1600, 1800, 2000},
+			Timestamps: timestampsExpected,
+		}
+		r.MetricName.Tags = []storage.Tag{
+			{
+				Key:   []byte("foo"),
+				Value: []byte("bar"),
+			},
+		}
+		resultExpected := []netstorage.Result{r}
 		f(q, resultExpected)
 	})
 	t.Run(`quantile(-2)`, func(t *testing.T) {

docs/CHANGELOG.md

@@ -16,6 +16,7 @@ The following tip changes can be tested by building VictoriaMetrics components f
 ## tip
 
 * BUGFIX: [vmagent](https://docs.victoriametrics.com/vmagent.html): properly assume role with AWS ECS credentials. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/2875). Thanks to @transacid for [the fix](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/2876).
+* BUGFIX: [MetricsQL](https://docs.victoriametrics.com/MetricsQL.html): return series from `q1` if `q2` doesn't return matching time series in the query `q1 ifnot q2`. Previously series from `q1` weren't returned in this case.
 
 ## [v1.79.0](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.79.0)