adds LabelNamesForMetricName for the series store

Signed-off-by: Cyril Tovena <cyril.tovena@gmail.com>

pkg/chunk/chunk_store.go

@@ -228,7 +228,49 @@ func (c *store) LabelValuesForMetricName(ctx context.Context, from, through mode
 		}
 		result = append(result, string(labelValue))
 	}
+	sort.Strings(result)
+	result = uniqueStrings(result)
+	return result, nil
+}
+
+// LabelNamesForMetricName retrieves all label names for a metric name.
+func (c *store) LabelNamesForMetricName(ctx context.Context, from, through model.Time, metricName string) ([]string, error) {
+	log, ctx := spanlogger.New(ctx, "ChunkStore.LabelNamesForMetricName")
+	defer log.Span.Finish()
+	level.Debug(log).Log("from", from, "through", through, "metricName", metricName)
+
+	shortcut, err := c.validateQueryTimeRange(ctx, &from, &through)
+	if err != nil {
+		return nil, err
+	} else if shortcut {
+		return nil, nil
+	}
+
+	chunks, err := c.lookupChunksByMetricName(ctx, from, through, nil, metricName)
+	if err != nil {
+		return nil, err
+	}
+	level.Debug(log).Log("Chunks in index", len(chunks))
+
+	// Filter out chunks that are not in the selected time range and keep a single chunk per fingerprint
+	filtered := filterChunksByTime(from, through, chunks)
+	filtered, keys := filterChunksByUniqueFingerPrint(filtered)
+	level.Debug(log).Log("Chunks post filtering", len(chunks))
 
+	// Now fetch the actual chunk data from Memcache / S3
+	allChunks, err := c.FetchChunks(ctx, filtered, keys)
+	if err != nil {
+		level.Error(log).Log("msg", "FetchChunks", "err", err)
+		return nil, err
+	}
+	var result []string
+	for _, c := range allChunks {
+		for _, l := range c.Metric {
+			if l.Name != model.MetricNameLabel {
+				result = append(result, string(l.Name))
+			}
+		}
+	}
 	sort.Strings(result)
 	result = uniqueStrings(result)
 	return result, nil

pkg/chunk/chunk_store_test.go

@@ -370,6 +370,108 @@ func TestChunkStore_LabelValuesForMetricName(t *testing.T) {
 
 }
 
+func TestChunkStore_LabelNamesForMetricName(t *testing.T) {
+	ctx := user.InjectOrgID(context.Background(), userID)
+	now := model.Now()
+
+	fooMetric1 := labels.Labels{
+		{Name: labels.MetricName, Value: "foo"},
+		{Name: "bar", Value: "baz"},
+		{Name: "flip", Value: "flop"},
+		{Name: "toms", Value: "code"},
+	}
+	fooMetric2 := labels.Labels{
+		{Name: labels.MetricName, Value: "foo"},
+		{Name: "bar", Value: "beep"},
+		{Name: "toms", Value: "code"},
+	}
+	fooMetric3 := labels.Labels{
+		{Name: labels.MetricName, Value: "foo"},
+		{Name: "bar", Value: "bop"},
+		{Name: "flip", Value: "flap"},
+	}
+
+	// barMetric1 is a subset of barMetric2 to test over-matching bug.
+	barMetric1 := labels.Labels{
+		{Name: labels.MetricName, Value: "bar"},
+		{Name: "bar", Value: "baz"},
+	}
+	barMetric2 := labels.Labels{
+		{Name: labels.MetricName, Value: "bar"},
+		{Name: "bar", Value: "baz"},
+		{Name: "toms", Value: "code"},
+	}
+
+	fooChunk1 := dummyChunkFor(now, fooMetric1)
+	fooChunk2 := dummyChunkFor(now, fooMetric2)
+	fooChunk3 := dummyChunkFor(now, fooMetric3)
+	fooChunk4 := dummyChunkFor(now.Add(-time.Hour), fooMetric1) // same series but different chunk
+
+	barChunk1 := dummyChunkFor(now, barMetric1)
+	barChunk2 := dummyChunkFor(now, barMetric2)
+
+	for _, tc := range []struct {
+		metricName string
+		expect     []string
+	}{
+		{
+			`foo`,
+			[]string{"bar", "flip", "toms"},
+		},
+		{
+			`bar`,
+			[]string{"bar", "toms"},
+		},
+	} {
+		for _, schema := range schemas {
+			for _, storeCase := range stores {
+				t.Run(fmt.Sprintf("%s / %s / %s ", tc.metricName, schema.name, storeCase.name), func(t *testing.T) {
+					t.Log("========= Running labelNames with metricName", tc.metricName, "with schema", schema.name)
+					storeCfg := storeCase.configFn()
+					store := newTestChunkStoreConfig(t, schema.name, storeCfg)
+					defer store.Stop()
+
+					if err := store.Put(ctx, []Chunk{
+						fooChunk1,
+						fooChunk2,
+						fooChunk3,
+						fooChunk4,
+						barChunk1,
+						barChunk2,
+					}); err != nil {
+						t.Fatal(err)
+					}
+
+					// Query with ordinary time-range
+					labelNames1, err := store.LabelNamesForMetricName(ctx, now.Add(-time.Hour), now, tc.metricName)
+					require.NoError(t, err)
+
+					if !reflect.DeepEqual(tc.expect, labelNames1) {
+						t.Fatalf("%s: wrong label name - %s", tc.metricName, test.Diff(tc.expect, labelNames1))
+					}
+
+					// Pushing end of time-range into future should yield exact same resultset
+					labelNames2, err := store.LabelNamesForMetricName(ctx, now.Add(-time.Hour), now.Add(time.Hour*24*10), tc.metricName)
+					require.NoError(t, err)
+
+					if !reflect.DeepEqual(tc.expect, labelNames2) {
+						t.Fatalf("%s: wrong label name - %s", tc.metricName, test.Diff(tc.expect, labelNames2))
+					}
+
+					// Query with both begin & end of time-range in future should yield empty resultset
+					labelNames3, err := store.LabelNamesForMetricName(ctx, now.Add(time.Hour), now.Add(time.Hour*2), tc.metricName)
+					require.NoError(t, err)
+					if len(labelNames3) != 0 {
+						t.Fatalf("%s: future query should yield empty resultset ... actually got %v label names: %#v",
+							tc.metricName, len(labelNames3), labelNames3)
+					}
+				})
+			}
+		}
+	}
+
+}
+
 // TestChunkStore_getMetricNameChunks tests if chunks are fetched correctly when we have the metric name
 func TestChunkStore_getMetricNameChunks(t *testing.T) {
 	ctx := user.InjectOrgID(context.Background(), userID)

pkg/chunk/chunk_store_utils.go

@@ -36,6 +36,22 @@ func keysFromChunks(chunks []Chunk) []string {
 	return keys
 }
 
+func filterChunksByUniqueFingerPrint(chunks []Chunk) ([]Chunk, []string) {
+	filtered := make([]Chunk, 0, len(chunks))
+	keys := make([]string, 0, len(chunks))
+	uniqueFp := map[model.Fingerprint]struct{}{}
+
+	for _, chunk := range chunks {
+		if _, ok := uniqueFp[chunk.Fingerprint]; ok {
+			continue
+		}
+		filtered = append(filtered, chunk)
+		keys = append(keys, chunk.ExternalKey())
+		uniqueFp[chunk.Fingerprint] = struct{}{}
+	}
+	return filtered, keys
+}
+
 func filterChunksByMatchers(chunks []Chunk, filters []*labels.Matcher) []Chunk {
 	filteredChunks := make([]Chunk, 0, len(chunks))
 outer:

pkg/chunk/composite_store.go

@@ -19,6 +19,7 @@ type Store interface {
 	// using the corresponding Fetcher (fetchers[i].FetchChunks(ctx, chunks[i], ...)
 	GetChunkRefs(ctx context.Context, from, through model.Time, matchers ...*labels.Matcher) ([][]Chunk, []*Fetcher, error)
 	LabelValuesForMetricName(ctx context.Context, from, through model.Time, metricName string, labelName string) ([]string, error)
+	LabelNamesForMetricName(ctx context.Context, from, through model.Time, metricName string) ([]string, error)
 	Stop()
 }
 
@@ -106,6 +107,20 @@ func (c compositeStore) LabelValuesForMetricName(ctx context.Context, from, thro
 	return result, err
 }
 
+// LabelNamesForMetricName retrieves all label names for a metric name.
+func (c compositeStore) LabelNamesForMetricName(ctx context.Context, from, through model.Time, metricName string) ([]string, error) {
+	var result []string
+	err := c.forStores(from, through, func(from, through model.Time, store Store) error {
+		labelNames, err := store.LabelNamesForMetricName(ctx, from, through, metricName)
+		if err != nil {
+			return err
+		}
+		result = append(result, labelNames...)
+		return nil
+	})
+	return result, err
+}
+
 func (c compositeStore) GetChunkRefs(ctx context.Context, from, through model.Time, matchers ...*labels.Matcher) ([][]Chunk, []*Fetcher, error) {
 	chunkIDs := [][]Chunk{}
 	fetchers := []*Fetcher{}

pkg/chunk/composite_store_test.go

@@ -32,6 +32,10 @@ func (m mockStore) GetChunkRefs(tx context.Context, from, through model.Time, ma
 	return nil, nil, nil
 }
 
+func (m mockStore) LabelNamesForMetricName(ctx context.Context, from, through model.Time, metricName string) ([]string, error) {
+	return nil, nil
+}
+
 func (m mockStore) Stop() {}
 
 func TestCompositeStore(t *testing.T) {

pkg/chunk/series_store.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"net/http"
+	"sort"
 
 	"github.com/go-kit/kit/log/level"
 	"github.com/prometheus/client_golang/prometheus"
@@ -191,6 +192,72 @@ func (c *seriesStore) GetChunkRefs(ctx context.Context, from, through model.Time
 	return [][]Chunk{chunks}, []*Fetcher{c.store.Fetcher}, nil
 }
 
+// LabelNamesForMetricName retrieves all label names for a metric name.
+func (c *seriesStore) LabelNamesForMetricName(ctx context.Context, from, through model.Time, metricName string) ([]string, error) {
+	log, ctx := spanlogger.New(ctx, "SeriesStore.LabelNamesForMetricName")
+	defer log.Span.Finish()
+
+	userID, err := user.ExtractOrgID(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	shortcut, err := c.validateQueryTimeRange(ctx, &from, &through)
+	if err != nil {
+		return nil, err
+	} else if shortcut {
+		return nil, nil
+	}
+	level.Debug(log).Log("metric", metricName)
+
+	// Fetch the series IDs from the index
+	seriesIDs, err := c.lookupSeriesByMetricNameMatchers(ctx, from, through, userID, metricName, nil)
+	if err != nil {
+		return nil, err
+	}
+	level.Debug(log).Log("series-ids", len(seriesIDs))
+
+	// Lookup the series in the index to get the chunks.
+	chunkIDs, err := c.lookupChunksBySeries(ctx, from, through, userID, seriesIDs)
+	if err != nil {
+		level.Error(log).Log("msg", "lookupChunksBySeries", "err", err)
+		return nil, err
+	}
+	level.Debug(log).Log("chunk-ids", len(chunkIDs))
+
+	chunks, err := c.convertChunkIDsToChunks(ctx, userID, chunkIDs)
+	if err != nil {
+		level.Error(log).Log("err", "convertChunkIDsToChunks", "err", err)
+		return nil, err
+	}
+
+	// Filter out chunks that are not in the selected time range and keep a single chunk per fingerprint
+	filtered := filterChunksByTime(from, through, chunks)
+	filtered, keys := filterChunksByUniqueFingerPrint(filtered)
+	level.Debug(log).Log("Chunks post filtering", len(chunks))
+
+	chunksPerQuery.Observe(float64(len(filtered)))
+
+	// Now fetch the actual chunk data from Memcache / S3
+	allChunks, err := c.FetchChunks(ctx, filtered, keys)
+	if err != nil {
+		level.Error(log).Log("msg", "FetchChunks", "err", err)
+		return nil, err
+	}
+
+	var result []string
+	for _, c := range allChunks {
+		for _, l := range c.Metric {
+			if l.Name != model.MetricNameLabel {
+				result = append(result, string(l.Name))
+			}
+		}
+	}
+	sort.Strings(result)
+	result = uniqueStrings(result)
+	return result, nil
+}
+
 func (c *seriesStore) lookupSeriesByMetricNameMatchers(ctx context.Context, from, through model.Time, userID, metricName string, matchers []*labels.Matcher) ([]string, error) {
 	log, ctx := spanlogger.New(ctx, "SeriesStore.lookupSeriesByMetricNameMatchers", "metricName", metricName, "matchers", len(matchers))
 	defer log.Span.Finish()