app/vmselect/promql: properly override label values from group_left and group_right lists like Prometheus does

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/577

app/vmselect/promql/binary_op.go

@@ -206,7 +206,7 @@ func groupJoin(singleTimeseriesSide string, be *metricsql.BinaryOpExpr, rvsLeft,
 		resetMetricGroupIfRequired(be, tsLeft)
 		if len(tssRight) == 1 {
 			// Easy case - right part contains only a single matching time series.
-			tsLeft.MetricName.AddMissingTags(joinTags, &tssRight[0].MetricName)
+			tsLeft.MetricName.SetTags(joinTags, &tssRight[0].MetricName)
 			rvsLeft = append(rvsLeft, tsLeft)
 			rvsRight = append(rvsRight, tssRight[0])
 			continue
@@ -225,7 +225,7 @@ func groupJoin(singleTimeseriesSide string, be *metricsql.BinaryOpExpr, rvsLeft,
 		for _, tsRight := range tssRight {
 			var tsCopy timeseries
 			tsCopy.CopyFromShallowTimestamps(tsLeft)
-			tsCopy.MetricName.AddMissingTags(joinTags, &tsRight.MetricName)
+			tsCopy.MetricName.SetTags(joinTags, &tsRight.MetricName)
 			bb.B = marshalMetricTagsSorted(bb.B[:0], &tsCopy.MetricName)
 			if tsExisting := m[string(bb.B)]; tsExisting != nil {
 				// Try merging tsExisting with tsRight if they don't overlap.

app/vmselect/promql/exec_test.go

@@ -2009,25 +2009,37 @@ func TestExecSuccess(t *testing.T) {
 	})
 	t.Run(`scalar * ignoring(foo) group_right vector`, func(t *testing.T) {
 		t.Parallel()
-		q := `sort_desc(2 * ignoring(foo) group_right(a,foo) (label_set(time(), "foo", "bar") or label_set(10, "foo", "qwert")))`
+		q := `sort_desc(label_set(2, "a", "2") * ignoring(foo,a) group_right(a) (label_set(time(), "foo", "bar", "a", "1"), label_set(10, "foo", "qwert")))`
 		r1 := netstorage.Result{
 			MetricName: metricNameExpected,
 			Values:     []float64{2000, 2400, 2800, 3200, 3600, 4000},
 			Timestamps: timestampsExpected,
 		}
-		r1.MetricName.Tags = []storage.Tag{{
-			Key:   []byte("foo"),
-			Value: []byte("bar"),
-		}}
+		r1.MetricName.Tags = []storage.Tag{
+			{
+				Key:   []byte("a"),
+				Value: []byte("2"),
+			},
+			{
+				Key:   []byte("foo"),
+				Value: []byte("bar"),
+			},
+		}
 		r2 := netstorage.Result{
 			MetricName: metricNameExpected,
 			Values:     []float64{20, 20, 20, 20, 20, 20},
 			Timestamps: timestampsExpected,
 		}
-		r2.MetricName.Tags = []storage.Tag{{
-			Key:   []byte("foo"),
-			Value: []byte("qwert"),
-		}}
+		r2.MetricName.Tags = []storage.Tag{
+			{
+				Key:   []byte("a"),
+				Value: []byte("2"),
+			},
+			{
+				Key:   []byte("foo"),
+				Value: []byte("qwert"),
+			},
+		}
 		resultExpected := []netstorage.Result{r1, r2}
 		f(q, resultExpected)
 	})
@@ -2342,9 +2354,9 @@ func TestExecSuccess(t *testing.T) {
 	t.Run(`vector + vector on group_left matching`, func(t *testing.T) {
 		t.Parallel()
 		q := `sort_desc(
-			(label_set(time(), "t1", "v123", "t2", "v3") or label_set(10, "t2", "v3", "xxx", "yy"))
+			(label_set(time(), "t1", "v123", "t2", "v3"), label_set(10, "t2", "v3", "xxx", "yy"))
 			+ on (foo, t2) group_left (t1, noxxx)
-			(label_set(100, "t1", "v1") or label_set(time(), "t2", "v3", "noxxx", "aa"))
+			(label_set(100, "t1", "v1"), label_set(time(), "t2", "v3", "noxxx", "aa"))
 		)`
 		r1 := netstorage.Result{
 			MetricName: metricNameExpected,
@@ -2356,10 +2368,6 @@ func TestExecSuccess(t *testing.T) {
 				Key:   []byte("noxxx"),
 				Value: []byte("aa"),
 			},
-			{
-				Key:   []byte("t1"),
-				Value: []byte("v123"),
-			},
 			{
 				Key:   []byte("t2"),
 				Value: []byte("v3"),

lib/storage/metric_name.go

@@ -298,20 +298,30 @@ func (mn *MetricName) GetTagValue(tagKey string) []byte {
 	return nil
 }
 
-// AddMissingTags adds tags from src with keys matching addTags.
-func (mn *MetricName) AddMissingTags(addTags []string, src *MetricName) {
-	if hasTag(addTags, metricGroupTagKey) {
-		mn.MetricGroup = append(mn.MetricGroup[:0], src.MetricGroup...)
-	}
-	for i := range src.Tags {
-		srcTag := &src.Tags[i]
-		if !hasTag(addTags, srcTag.Key) {
+// SetTags sets tags from src with keys matching addTags.
+func (mn *MetricName) SetTags(addTags []string, src *MetricName) {
+	for _, tagName := range addTags {
+		if tagName == string(metricGroupTagKey) {
+			mn.MetricGroup = append(mn.MetricGroup[:0], src.MetricGroup...)
+			continue
+		}
+		var srcTag *Tag
+		for i := range src.Tags {
+			t := &src.Tags[i]
+			if string(t.Key) == tagName {
+				srcTag = t
+				break
+			}
+		}
+		if srcTag == nil {
+			mn.RemoveTag(tagName)
 			continue
 		}
 		found := false
-		for j := range mn.Tags {
-			tag := &mn.Tags[j]
-			if string(tag.Key) == string(srcTag.Key) {
+		for i := range mn.Tags {
+			t := &mn.Tags[i]
+			if string(t.Key) == tagName {
+				t.Value = append(t.Value[:0], srcTag.Value...)
 				found = true
 				break
 			}