LabelValuesExcluding: Fix corner case

Signed-off-by: Arve Knudsen <[email protected]>

storage/labelvalues_test.go

@@ -10,7 +10,7 @@ import (
 func TestListLabelValues(t *testing.T) {
 	t.Run("lets you traverse a slice of label values", func(t *testing.T) {
 		input := []string{"a", "b", "c", "d"}
-		it := NewListLabelValues(input)
+		it := NewListLabelValues(input, nil)
 		t.Cleanup(func() {
 			require.NoError(t, it.Close())
 		})
@@ -25,7 +25,7 @@ func TestListLabelValues(t *testing.T) {
 	})
 
 	t.Run("can be initialized with an empty slice", func(t *testing.T) {
-		it := NewListLabelValues([]string{})
+		it := NewListLabelValues([]string{}, nil)
 		t.Cleanup(func() {
 			require.NoError(t, it.Close())
 		})
@@ -36,7 +36,7 @@ func TestListLabelValues(t *testing.T) {
 	})
 
 	t.Run("can be initialized with a nil slice", func(t *testing.T) {
-		it := NewListLabelValues(nil)
+		it := NewListLabelValues(nil, nil)
 		t.Cleanup(func() {
 			require.NoError(t, it.Close())
 		})

tsdb/block_test.go

@@ -314,6 +314,10 @@ func TestLabelValuesStream_WithMatchers(t *testing.T) {
 			"unique", fmt.Sprintf("value%d", i),
 		), []chunks.Sample{sample{100, 0, nil, nil}}))
 	}
+	// Add another series with an overlapping unique label, but leaving out the tens label
+	seriesEntries = append(seriesEntries, storage.NewListSeries(labels.FromStrings(
+		"unique", "value99",
+	), []chunks.Sample{sample{100, 0, nil, nil}}))
 
 	ctx := context.Background()
 
@@ -371,6 +375,15 @@ func TestLabelValuesStream_WithMatchers(t *testing.T) {
 				labels.MustNewMatcher(labels.MatchNotEqual, "tens", ""),
 			},
 			expectedValues: uniqueWithout30s,
+		}, {
+			// In this case, we query for the "unique" label where the "tens" label is absent.
+			// We have one series where "tens" is empty (unique="value99"), but also another with
+			// the same value for "unique" and "tens" present. Make sure that unique="value99" is
+			// still found.
+			name:           "get unique ID where tens is empty",
+			labelName:      "unique",
+			matchers:       []*labels.Matcher{labels.MustNewMatcher(labels.MatchEqual, "tens", "")},
+			expectedValues: []string{"value99"},
 		},
 	}
 	for _, tt := range testCases {

tsdb/head_test.go

@@ -2851,6 +2851,11 @@ func TestHeadLabelValuesStream_WithMatchers(t *testing.T) {
 		), 100, 0)
 		require.NoError(t, err)
 	}
+	// Add another series with an overlapping unique label, but leaving out the tens label
+	_, err := app.Append(0, labels.FromStrings(
+		"unique", "value99",
+	), 100, 0)
+	require.NoError(t, err)
 	require.NoError(t, app.Commit())
 
 	indexReader := head.indexRange(0, 200)
@@ -2904,6 +2909,15 @@ func TestHeadLabelValuesStream_WithMatchers(t *testing.T) {
 			labelName:      "tens",
 			matchers:       []*labels.Matcher{labels.MustNewMatcher(labels.MatchEqual, "unique", "")},
 			expectedValues: nil,
+		}, {
+			// In this case, we query for the "unique" label where the "tens" label is absent.
+			// We have one series where "tens" is empty (unique="value99"), but also another with
+			// the same value for "unique" and "tens" present. Make sure that unique="value99" is
+			// still found.
+			name:           "get unique ID where tens is empty",
+			labelName:      "unique",
+			matchers:       []*labels.Matcher{labels.MustNewMatcher(labels.MatchEqual, "tens", "")},
+			expectedValues: []string{"value99"},
 		},
 	}
 	for _, tt := range testCases {

tsdb/index/labelvalues.go

@@ -206,7 +206,7 @@ func (r *Reader) labelValuesForV1(postings Postings, name string, includeMatches
 	slices.Sort(vals)
 	return &intersectLabelValuesV1{
 		postingOffsets: e,
-		values:         storage.NewListLabelValues(vals),
+		values:         storage.NewListLabelValues(vals, nil),
 		postings:       NewPostingsCloner(postings),
 		b:              r.b,
 		dec:            r.dec,
@@ -494,7 +494,40 @@ func (p *MemPostings) labelValuesFor(postings Postings, name string, includeMatc
 	}
 
 	slices.Sort(vals)
-	return storage.NewListLabelValues(vals)
+	return storage.NewListLabelValues(vals, nil)
+}
+
+// LabelValuesFromSeries returns all unique label values from r for given label name from supplied series. Values are not sorted.
+// buf is space for holding the result (if it isn't big enough, it will be ignored), may be nil.
+func LabelValuesFromSeries(lg LabelsGetter, labelName string, refs []storage.SeriesRef, buf []string) ([]string, error) {
+	values := make(map[string]struct{}, len(buf))
+
+	var builder labels.ScratchBuilder
+	for _, ref := range refs {
+		err := lg.Labels(ref, &builder)
+		// Postings may be stale. Skip if no underlying series exists.
+		if errors.Is(err, storage.ErrNotFound) {
+			continue
+		}
+		if err != nil {
+			return nil, fmt.Errorf("label values for label %s: %w", labelName, err)
+		}
+
+		v := builder.Labels().Get(labelName)
+		if v != "" {
+			values[v] = struct{}{}
+		}
+	}
+
+	if cap(buf) >= len(values) {
+		buf = buf[:0]
+	} else {
+		buf = make([]string, 0, len(values))
+	}
+	for v := range values {
+		buf = append(buf, v)
+	}
+	return buf, nil
 }
 
 // intersect returns whether p1 and p2 have at least one series in common.
@@ -598,4 +631,3 @@ func (p *MemPostings) PostingsForRegexp(ctx context.Context, m *labels.Matcher)
 
 	return Merge(ctx, its...)
 }
-

tsdb/index/labelvalues_test.go

@@ -230,7 +230,7 @@ func TestMemPostings_LabelValuesFor(t *testing.T) {
 	t.Run("filtering based on non-empty postings", func(t *testing.T) {
 		p := mp.Get("a", "1")
 
-		it := mp.LabelValuesFor(p, "b")
+		it := mp.LabelValuesFor(p, "b", nil)
 		t.Cleanup(func() {
 			require.NoError(t, it.Close())
 		})
@@ -248,7 +248,7 @@ func TestMemPostings_LabelValuesFor(t *testing.T) {
 	t.Run("requesting a non-existent label value", func(t *testing.T) {
 		p := mp.Get("a", "1")
 
-		it := mp.LabelValuesFor(p, "c")
+		it := mp.LabelValuesFor(p, "c", nil)
 		t.Cleanup(func() {
 			require.NoError(t, it.Close())
 		})
@@ -259,7 +259,7 @@ func TestMemPostings_LabelValuesFor(t *testing.T) {
 	})
 
 	t.Run("filtering based on empty postings", func(t *testing.T) {
-		it := mp.LabelValuesFor(EmptyPostings(), "a")
+		it := mp.LabelValuesFor(EmptyPostings(), "a", nil)
 		t.Cleanup(func() {
 			require.NoError(t, it.Close())
 		})
@@ -272,7 +272,7 @@ func TestMemPostings_LabelValuesFor(t *testing.T) {
 	t.Run("filtering based on a postings set missing the label", func(t *testing.T) {
 		p := mp.Get("d", "1")
 
-		it := mp.LabelValuesFor(p, "a")
+		it := mp.LabelValuesFor(p, "a", nil)
 		t.Cleanup(func() {
 			require.NoError(t, it.Close())
 		})