Merge 288c8ce273 into 25aee26a57

storage/remote/client.go

@@ -19,6 +19,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"math"
 	"net/http"
 	"net/http/httptrace"
 	"strconv"
@@ -112,8 +113,9 @@ type Client struct {
 	Client     *http.Client
 	timeout    time.Duration
 
-	retryOnRateLimit bool
-	chunkedReadLimit uint64
+	retryOnRateLimit      bool
+	chunkedReadLimit      uint64
+	acceptedResponseTypes []prompb.ReadRequest_ResponseType
 
 	readQueries         prometheus.Gauge
 	readQueriesTotal    *prometheus.CounterVec
@@ -125,23 +127,25 @@ type Client struct {
 
 // ClientConfig configures a client.
 type ClientConfig struct {
-	URL              *config_util.URL
-	Timeout          model.Duration
-	HTTPClientConfig config_util.HTTPClientConfig
-	SigV4Config      *sigv4.SigV4Config
-	AzureADConfig    *azuread.AzureADConfig
-	GoogleIAMConfig  *googleiam.Config
-	Headers          map[string]string
-	RetryOnRateLimit bool
-	WriteProtoMsg    config.RemoteWriteProtoMsg
-	ChunkedReadLimit uint64
-	RoundRobinDNS    bool
+	URL                   *config_util.URL
+	Timeout               model.Duration
+	HTTPClientConfig      config_util.HTTPClientConfig
+	SigV4Config           *sigv4.SigV4Config
+	AzureADConfig         *azuread.AzureADConfig
+	GoogleIAMConfig       *googleiam.Config
+	Headers               map[string]string
+	RetryOnRateLimit      bool
+	WriteProtoMsg         config.RemoteWriteProtoMsg
+	ChunkedReadLimit      uint64
+	RoundRobinDNS         bool
+	AcceptedResponseTypes []prompb.ReadRequest_ResponseType
 }
 
 // ReadClient will request the STREAMED_XOR_CHUNKS method of remote read but can
 // also fall back to the SAMPLES method if necessary.
 type ReadClient interface {
 	Read(ctx context.Context, query *prompb.Query, sortSeries bool) (storage.SeriesSet, error)
+	ReadMultiple(ctx context.Context, queries []*prompb.Query, sortSeries bool) (storage.SeriesSet, error)
 }
 
 // NewReadClient creates a new client for remote read.
@@ -157,15 +161,22 @@ func NewReadClient(name string, conf *ClientConfig, optFuncs ...config_util.HTTP
 	}
 	httpClient.Transport = otelhttp.NewTransport(t)
 
+	// Set accepted response types, default to existing behavior if not specified
+	acceptedResponseTypes := conf.AcceptedResponseTypes
+	if len(acceptedResponseTypes) == 0 {
+		acceptedResponseTypes = AcceptedResponseTypes
+	}
+
 	return &Client{
-		remoteName:          name,
-		urlString:           conf.URL.String(),
-		Client:              httpClient,
-		timeout:             time.Duration(conf.Timeout),
-		chunkedReadLimit:    conf.ChunkedReadLimit,
-		readQueries:         remoteReadQueries.WithLabelValues(name, conf.URL.String()),
-		readQueriesTotal:    remoteReadQueriesTotal.MustCurryWith(prometheus.Labels{remoteName: name, endpoint: conf.URL.String()}),
-		readQueriesDuration: remoteReadQueryDuration.MustCurryWith(prometheus.Labels{remoteName: name, endpoint: conf.URL.String()}),
+		remoteName:            name,
+		urlString:             conf.URL.String(),
+		Client:                httpClient,
+		timeout:               time.Duration(conf.Timeout),
+		chunkedReadLimit:      conf.ChunkedReadLimit,
+		acceptedResponseTypes: acceptedResponseTypes,
+		readQueries:           remoteReadQueries.WithLabelValues(name, conf.URL.String()),
+		readQueriesTotal:      remoteReadQueriesTotal.MustCurryWith(prometheus.Labels{remoteName: name, endpoint: conf.URL.String()}),
+		readQueriesDuration:   remoteReadQueryDuration.MustCurryWith(prometheus.Labels{remoteName: name, endpoint: conf.URL.String()}),
 	}, nil
 }
 
@@ -337,27 +348,44 @@ func (c *Client) Endpoint() string {
 	return c.urlString
 }
 
-// Read reads from a remote endpoint. The sortSeries parameter is only respected in the case of a sampled response;
+// Read reads from a remote endpoint. The sortSeries parameter is only respected in the case of a samples response;
 // chunked responses arrive already sorted by the server.
 func (c *Client) Read(ctx context.Context, query *prompb.Query, sortSeries bool) (storage.SeriesSet, error) {
+	return c.ReadMultiple(ctx, []*prompb.Query{query}, sortSeries)
+}
+
+// ReadMultiple reads from a remote endpoint using multiple queries in a single request.
+// The sortSeries parameter is only respected in the case of a samples response;
+// chunked responses arrive already sorted by the server.
+// Returns a single SeriesSet with interleaved series from all queries.
+func (c *Client) ReadMultiple(ctx context.Context, queries []*prompb.Query, sortSeries bool) (storage.SeriesSet, error) {
 	c.readQueries.Inc()
 	defer c.readQueries.Dec()
 
 	req := &prompb.ReadRequest{
-		// TODO: Support batching multiple queries into one read request,
-		// as the protobuf interface allows for it.
-		Queries:               []*prompb.Query{query},
-		AcceptedResponseTypes: AcceptedResponseTypes,
+		Queries:               queries,
+		AcceptedResponseTypes: c.acceptedResponseTypes,
 	}
+
+	httpResp, cancel, start, err := c.executeReadRequest(ctx, req, "Remote Read Multiple")
+	if err != nil {
+		return nil, err
+	}
+
+	return c.handleReadResponse(httpResp, req, queries, sortSeries, start, cancel)
+}
+
+// executeReadRequest creates and executes an HTTP request for reading data.
+func (c *Client) executeReadRequest(ctx context.Context, req *prompb.ReadRequest, spanName string) (*http.Response, context.CancelFunc, time.Time, error) {
 	data, err := proto.Marshal(req)
 	if err != nil {
-		return nil, fmt.Errorf("unable to marshal read request: %w", err)
+		return nil, nil, time.Time{}, fmt.Errorf("unable to marshal read request: %w", err)
 	}
 
 	compressed := snappy.Encode(nil, data)
 	httpReq, err := http.NewRequest(http.MethodPost, c.urlString, bytes.NewReader(compressed))
 	if err != nil {
-		return nil, fmt.Errorf("unable to create request: %w", err)
+		return nil, nil, time.Time{}, fmt.Errorf("unable to create request: %w", err)
 	}
 	httpReq.Header.Add("Content-Encoding", "snappy")
 	httpReq.Header.Add("Accept-Encoding", "snappy")
@@ -368,16 +396,21 @@ func (c *Client) Read(ctx context.Context, query *prompb.Query, sortSeries bool)
 	errTimeout := fmt.Errorf("%w: request timed out after %s", context.DeadlineExceeded, c.timeout)
 	ctx, cancel := context.WithTimeoutCause(ctx, c.timeout, errTimeout)
 
-	ctx, span := otel.Tracer("").Start(ctx, "Remote Read", trace.WithSpanKind(trace.SpanKindClient))
+	ctx, span := otel.Tracer("").Start(ctx, spanName, trace.WithSpanKind(trace.SpanKindClient))
 	defer span.End()
 
 	start := time.Now()
 	httpResp, err := c.Client.Do(httpReq.WithContext(ctx))
 	if err != nil {
 		cancel()
-		return nil, fmt.Errorf("error sending request: %w", err)
+		return nil, nil, time.Time{}, fmt.Errorf("error sending request: %w", err)
 	}
 
+	return httpResp, cancel, start, nil
+}
+
+// handleReadResponse processes the HTTP response and returns a SeriesSet.
+func (c *Client) handleReadResponse(httpResp *http.Response, req *prompb.ReadRequest, queries []*prompb.Query, sortSeries bool, start time.Time, cancel context.CancelFunc) (storage.SeriesSet, error) {
 	if httpResp.StatusCode/100 != 2 {
 		// Make an attempt at getting an error message.
 		body, _ := io.ReadAll(httpResp.Body)
@@ -393,16 +426,16 @@ func (c *Client) Read(ctx context.Context, query *prompb.Query, sortSeries bool)
 
 	switch {
 	case strings.HasPrefix(contentType, "application/x-protobuf"):
-		c.readQueriesDuration.WithLabelValues("sampled").Observe(time.Since(start).Seconds())
-		c.readQueriesTotal.WithLabelValues("sampled", strconv.Itoa(httpResp.StatusCode)).Inc()
-		ss, err := c.handleSampledResponse(req, httpResp, sortSeries)
+		c.readQueriesDuration.WithLabelValues("samples").Observe(time.Since(start).Seconds())
+		c.readQueriesTotal.WithLabelValues("samples", strconv.Itoa(httpResp.StatusCode)).Inc()
+		ss, err := c.handleSamplesResponseImpl(req, httpResp, sortSeries)
 		cancel()
 		return ss, err
 	case strings.HasPrefix(contentType, "application/x-streamed-protobuf; proto=prometheus.ChunkedReadResponse"):
 		c.readQueriesDuration.WithLabelValues("chunked").Observe(time.Since(start).Seconds())
 
 		s := NewChunkedReader(httpResp.Body, c.chunkedReadLimit, nil)
-		return NewChunkedSeriesSet(s, httpResp.Body, query.StartTimestampMs, query.EndTimestampMs, func(err error) {
+		return c.handleChunkedResponseImpl(s, httpResp, queries, func(err error) {
 			code := strconv.Itoa(httpResp.StatusCode)
 			if !errors.Is(err, io.EOF) {
 				code = "aborted_stream"
@@ -418,7 +451,8 @@ func (c *Client) Read(ctx context.Context, query *prompb.Query, sortSeries bool)
 	}
 }
 
-func (c *Client) handleSampledResponse(req *prompb.ReadRequest, httpResp *http.Response, sortSeries bool) (storage.SeriesSet, error) {
+// handleSamplesResponseImpl handles samples responses for both single and multiple queries.
+func (c *Client) handleSamplesResponseImpl(req *prompb.ReadRequest, httpResp *http.Response, sortSeries bool) (storage.SeriesSet, error) {
 	compressed, err := io.ReadAll(httpResp.Body)
 	if err != nil {
 		return nil, fmt.Errorf("error reading response. HTTP status code: %s: %w", httpResp.Status, err)
@@ -443,8 +477,60 @@ func (c *Client) handleSampledResponse(req *prompb.ReadRequest, httpResp *http.R
 		return nil, fmt.Errorf("responses: want %d, got %d", len(req.Queries), len(resp.Results))
 	}
 
-	// This client does not batch queries so there's always only 1 result.
-	res := resp.Results[0]
-
-	return FromQueryResult(sortSeries, res), nil
+	return combineQueryResults(resp.Results, sortSeries)
+}
+
+// combineQueryResults combines multiple query results into a single SeriesSet,
+// handling both sorted and unsorted cases appropriately.
+func combineQueryResults(results []*prompb.QueryResult, sortSeries bool) (storage.SeriesSet, error) {
+	if len(results) == 0 {
+		return &concreteSeriesSet{series: nil, cur: 0}, nil
+	}
+
+	if len(results) == 1 {
+		return FromQueryResult(sortSeries, results[0]), nil
+	}
+
+	// Multiple queries case - combine all results
+	if sortSeries {
+		// When sorting is requested, use MergeSeriesSet which can efficiently merge sorted inputs
+		var allSeriesSets []storage.SeriesSet
+		for _, result := range results {
+			seriesSet := FromQueryResult(sortSeries, result)
+			if err := seriesSet.Err(); err != nil {
+				return nil, fmt.Errorf("error reading series from query result: %w", err)
+			}
+			allSeriesSets = append(allSeriesSets, seriesSet)
+		}
+		return storage.NewMergeSeriesSet(allSeriesSets, 0, storage.ChainedSeriesMerge), nil
+	}
+
+	// When sorting is not requested, just concatenate all series without using MergeSeriesSet
+	// since MergeSeriesSet requires sorted inputs
+	var allSeries []storage.Series
+	for _, result := range results {
+		seriesSet := FromQueryResult(sortSeries, result)
+		for seriesSet.Next() {
+			allSeries = append(allSeries, seriesSet.At())
+		}
+		if err := seriesSet.Err(); err != nil {
+			return nil, fmt.Errorf("error reading series from query result: %w", err)
+		}
+	}
+
+	return &concreteSeriesSet{series: allSeries, cur: 0}, nil
+}
+
+// handleChunkedResponseImpl handles chunked responses for both single and multiple queries.
+func (c *Client) handleChunkedResponseImpl(s *ChunkedReader, httpResp *http.Response, queries []*prompb.Query, onClose func(error)) storage.SeriesSet {
+	// For multiple queries in chunked response, we'll still use the existing infrastructure
+	// but we need to provide the timestamp range that covers all queries
+	var minStartTs, maxEndTs int64 = math.MaxInt64, math.MinInt64
+
+	for _, query := range queries {
+		minStartTs = min(minStartTs, query.StartTimestampMs)
+		maxEndTs = max(maxEndTs, query.EndTimestampMs)
+	}
+
+	return NewChunkedSeriesSet(s, httpResp.Body, minStartTs, maxEndTs, onClose)
 }

storage/remote/read_test.go

@@ -28,6 +28,7 @@ import (
 	"github.com/prometheus/prometheus/model/labels"
 	"github.com/prometheus/prometheus/prompb"
 	"github.com/prometheus/prometheus/storage"
+	"github.com/prometheus/prometheus/tsdb/chunkenc"
 	"github.com/prometheus/prometheus/util/annotations"
 	"github.com/prometheus/prometheus/util/testutil"
 )
@@ -194,9 +195,10 @@ func TestSeriesSetFilter(t *testing.T) {
 }
 
 type mockedRemoteClient struct {
-	got   *prompb.Query
-	store []*prompb.TimeSeries
-	b     labels.ScratchBuilder
+	got         *prompb.Query
+	gotMultiple []*prompb.Query
+	store       []*prompb.TimeSeries
+	b           labels.ScratchBuilder
 }
 
 func (c *mockedRemoteClient) Read(_ context.Context, query *prompb.Query, sortSeries bool) (storage.SeriesSet, error) {
@@ -224,15 +226,69 @@ func (c *mockedRemoteClient) Read(_ context.Context, query *prompb.Query, sortSe
 			}
 		}
 
-		if !notMatch {
-			q.Timeseries = append(q.Timeseries, &prompb.TimeSeries{Labels: s.Labels})
+		if notMatch {
+			continue
 		}
+		// Filter samples by query time range
+		var filteredSamples []prompb.Sample
+		for _, sample := range s.Samples {
+			if sample.Timestamp >= query.StartTimestampMs && sample.Timestamp <= query.EndTimestampMs {
+				filteredSamples = append(filteredSamples, sample)
+			}
+		}
+		q.Timeseries = append(q.Timeseries, &prompb.TimeSeries{Labels: s.Labels, Samples: filteredSamples})
 	}
 	return FromQueryResult(sortSeries, q), nil
 }
 
+func (c *mockedRemoteClient) ReadMultiple(_ context.Context, queries []*prompb.Query, sortSeries bool) (storage.SeriesSet, error) {
+	// Store the queries for verification
+	c.gotMultiple = make([]*prompb.Query, len(queries))
+	copy(c.gotMultiple, queries)
+
+	// Simulate the same behavior as the real client
+	var results []*prompb.QueryResult
+	for _, query := range queries {
+		matchers, err := FromLabelMatchers(query.Matchers)
+		if err != nil {
+			return nil, err
+		}
+
+		q := &prompb.QueryResult{}
+		for _, s := range c.store {
+			l := s.ToLabels(&c.b, nil)
+			var notMatch bool
+
+			for _, m := range matchers {
+				v := l.Get(m.Name)
+				if !m.Matches(v) {
+					notMatch = true
+					break
+				}
+			}
+
+			if notMatch {
+				continue
+			}
+			// Filter samples by query time range
+			var filteredSamples []prompb.Sample
+			for _, sample := range s.Samples {
+				if sample.Timestamp >= query.StartTimestampMs && sample.Timestamp <= query.EndTimestampMs {
+					filteredSamples = append(filteredSamples, sample)
+				}
+			}
+			q.Timeseries = append(q.Timeseries, &prompb.TimeSeries{Labels: s.Labels, Samples: filteredSamples})
+		}
+		results = append(results, q)
+	}
+
+	// Use the same logic as the real client
+	return combineQueryResults(results, sortSeries)
+}
+
 func (c *mockedRemoteClient) reset() {
 	c.got = nil
+	c.gotMultiple = nil
 }
 
 // NOTE: We don't need to test ChunkQuerier as it's uses querier for all operations anyway.
@@ -494,3 +550,336 @@ func TestSampleAndChunkQueryableClient(t *testing.T) {
 		})
 	}
 }
+
+func TestReadMultiple(t *testing.T) {
+	const sampleIntervalMs = 250
+
+	// Helper function to calculate series multiplier based on labels
+	getSeriesMultiplier := func(labels []prompb.Label) uint64 {
+		// Create a simple hash from labels to generate unique values per series
+		labelHash := uint64(0)
+		for _, label := range labels {
+			for _, b := range label.Name + label.Value {
+				labelHash = labelHash*31 + uint64(b)
+			}
+		}
+		return labelHash % sampleIntervalMs
+	}
+
+	// Helper function to generate a complete time series with samples at 250ms intervals
+	// Each series gets different sample values based on a hash of their labels
+	generateSeries := func(labels []prompb.Label, startMs, endMs int64) *prompb.TimeSeries {
+		seriesMultiplier := getSeriesMultiplier(labels)
+
+		var samples []prompb.Sample
+		for ts := startMs; ts <= endMs; ts += sampleIntervalMs {
+			samples = append(samples, prompb.Sample{
+				Timestamp: ts,
+				Value:     float64(ts + int64(seriesMultiplier)), // Unique value per series
+			})
+		}
+
+		return &prompb.TimeSeries{
+			Labels:  labels,
+			Samples: samples,
+		}
+	}
+
+	m := &mockedRemoteClient{
+		store: []*prompb.TimeSeries{
+			generateSeries([]prompb.Label{{Name: "job", Value: "prometheus"}}, 0, 10000),
+			generateSeries([]prompb.Label{{Name: "job", Value: "node_exporter"}}, 0, 10000),
+			generateSeries([]prompb.Label{{Name: "job", Value: "cadvisor"}, {Name: "region", Value: "us"}}, 0, 10000),
+			generateSeries([]prompb.Label{{Name: "instance", Value: "localhost:9090"}}, 0, 10000),
+		},
+		b: labels.NewScratchBuilder(0),
+	}
+
+	testCases := []struct {
+		name            string
+		queries         []*prompb.Query
+		expectedResults []*prompb.TimeSeries
+	}{
+		{
+			name: "single query",
+			queries: []*prompb.Query{
+				{
+					StartTimestampMs: 1000,
+					EndTimestampMs:   2000,
+					Matchers: []*prompb.LabelMatcher{
+						{Type: prompb.LabelMatcher_EQ, Name: "job", Value: "prometheus"},
+					},
+				},
+			},
+			expectedResults: []*prompb.TimeSeries{
+				generateSeries([]prompb.Label{{Name: "job", Value: "prometheus"}}, 1000, 2000),
+			},
+		},
+		{
+			name: "multiple queries - different matchers",
+			queries: []*prompb.Query{
+				{
+					StartTimestampMs: 1000,
+					EndTimestampMs:   2000,
+					Matchers: []*prompb.LabelMatcher{
+						{Type: prompb.LabelMatcher_EQ, Name: "job", Value: "prometheus"},
+					},
+				},
+				{
+					StartTimestampMs: 1500,
+					EndTimestampMs:   2500,
+					Matchers: []*prompb.LabelMatcher{
+						{Type: prompb.LabelMatcher_EQ, Name: "job", Value: "node_exporter"},
+					},
+				},
+			},
+			expectedResults: []*prompb.TimeSeries{
+				generateSeries([]prompb.Label{{Name: "job", Value: "node_exporter"}}, 1500, 2500),
+				generateSeries([]prompb.Label{{Name: "job", Value: "prometheus"}}, 1000, 2000),
+			},
+		},
+		{
+			name: "multiple queries - overlapping results",
+			queries: []*prompb.Query{
+				{
+					StartTimestampMs: 1000,
+					EndTimestampMs:   2000,
+					Matchers: []*prompb.LabelMatcher{
+						{Type: prompb.LabelMatcher_RE, Name: "job", Value: "prometheus|node_exporter"},
+					},
+				},
+				{
+					StartTimestampMs: 1500,
+					EndTimestampMs:   2500,
+					Matchers: []*prompb.LabelMatcher{
+						{Type: prompb.LabelMatcher_EQ, Name: "region", Value: "us"},
+					},
+				},
+			},
+			expectedResults: []*prompb.TimeSeries{
+				generateSeries([]prompb.Label{{Name: "job", Value: "cadvisor"}, {Name: "region", Value: "us"}}, 1500, 2500),
+				generateSeries([]prompb.Label{{Name: "job", Value: "node_exporter"}}, 1000, 2000),
+				generateSeries([]prompb.Label{{Name: "job", Value: "prometheus"}}, 1000, 2000),
+			},
+		},
+		{
+			name: "query with no results",
+			queries: []*prompb.Query{
+				{
+					StartTimestampMs: 1000,
+					EndTimestampMs:   2000,
+					Matchers: []*prompb.LabelMatcher{
+						{Type: prompb.LabelMatcher_EQ, Name: "job", Value: "nonexistent"},
+					},
+				},
+			},
+			expectedResults: nil, // empty result
+		},
+		{
+			name:            "empty query list",
+			queries:         []*prompb.Query{},
+			expectedResults: nil,
+		},
+		{
+			name: "three queries with mixed results",
+			queries: []*prompb.Query{
+				{
+					StartTimestampMs: 1000,
+					EndTimestampMs:   2000,
+					Matchers: []*prompb.LabelMatcher{
+						{Type: prompb.LabelMatcher_EQ, Name: "job", Value: "prometheus"},
+					},
+				},
+				{
+					StartTimestampMs: 1500,
+					EndTimestampMs:   2500,
+					Matchers: []*prompb.LabelMatcher{
+						{Type: prompb.LabelMatcher_EQ, Name: "job", Value: "nonexistent"},
+					},
+				},
+				{
+					StartTimestampMs: 2000,
+					EndTimestampMs:   3000,
+					Matchers: []*prompb.LabelMatcher{
+						{Type: prompb.LabelMatcher_EQ, Name: "instance", Value: "localhost:9090"},
+					},
+				},
+			},
+			expectedResults: []*prompb.TimeSeries{
+				generateSeries([]prompb.Label{{Name: "instance", Value: "localhost:9090"}}, 2000, 3000),
+				generateSeries([]prompb.Label{{Name: "job", Value: "prometheus"}}, 1000, 2000),
+			},
+		},
+		{
+			name: "same matchers with overlapping time ranges",
+			queries: []*prompb.Query{
+				{
+					StartTimestampMs: 1000,
+					EndTimestampMs:   5000,
+					Matchers: []*prompb.LabelMatcher{
+						{Type: prompb.LabelMatcher_EQ, Name: "region", Value: "us"},
+					},
+				},
+				{
+					StartTimestampMs: 3000,
+					EndTimestampMs:   8000,
+					Matchers: []*prompb.LabelMatcher{
+						{Type: prompb.LabelMatcher_EQ, Name: "region", Value: "us"},
+					},
+				},
+			},
+			expectedResults: []*prompb.TimeSeries{
+				generateSeries([]prompb.Label{{Name: "job", Value: "cadvisor"}, {Name: "region", Value: "us"}}, 1000, 8000),
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			m.reset()
+
+			result, err := m.ReadMultiple(context.Background(), tc.queries, true)
+			require.NoError(t, err)
+
+			// Verify the queries were stored correctly
+			require.Equal(t, tc.queries, m.gotMultiple)
+
+			// Verify the combined result matches expected
+			var got []*prompb.TimeSeries
+			for result.Next() {
+				series := result.At()
+				var samples []prompb.Sample
+				iterator := series.Iterator(nil)
+
+				// Collect actual samples
+				for iterator.Next() != chunkenc.ValNone {
+					ts, value := iterator.At()
+					samples = append(samples, prompb.Sample{
+						Timestamp: ts,
+						Value:     value,
+					})
+				}
+				require.NoError(t, iterator.Err())
+
+				got = append(got, &prompb.TimeSeries{
+					Labels:  prompb.FromLabels(series.Labels(), nil),
+					Samples: samples,
+				})
+			}
+			require.NoError(t, result.Err())
+
+			require.ElementsMatch(t, tc.expectedResults, got)
+		})
+	}
+}
+
+func TestReadMultipleErrorHandling(t *testing.T) {
+	m := &mockedRemoteClient{
+		store: []*prompb.TimeSeries{
+			{Labels: []prompb.Label{{Name: "job", Value: "prometheus"}}},
+		},
+		b: labels.NewScratchBuilder(0),
+	}
+
+	// Test with invalid matcher - should return error
+	queries := []*prompb.Query{
+		{
+			StartTimestampMs: 1000,
+			EndTimestampMs:   2000,
+			Matchers: []*prompb.LabelMatcher{
+				{Type: prompb.LabelMatcher_Type(999), Name: "job", Value: "prometheus"}, // invalid matcher type
+			},
+		},
+	}
+
+	result, err := m.ReadMultiple(context.Background(), queries, true)
+	require.Error(t, err)
+	require.Nil(t, result)
+}
+
+func TestReadMultipleSorting(t *testing.T) {
+	// Test data with labels designed to test sorting behavior
+	// When sorted: aaa < bbb < ccc
+	// When unsorted: order depends on processing order
+	m := &mockedRemoteClient{
+		store: []*prompb.TimeSeries{
+			{Labels: []prompb.Label{{Name: "series", Value: "ccc"}}}, // Will be returned by query 1
+			{Labels: []prompb.Label{{Name: "series", Value: "aaa"}}}, // Will be returned by query 2
+			{Labels: []prompb.Label{{Name: "series", Value: "bbb"}}}, // Will be returned by both queries (overlapping)
+		},
+		b: labels.NewScratchBuilder(0),
+	}
+
+	testCases := []struct {
+		name          string
+		queries       []*prompb.Query
+		sortSeries    bool
+		expectedOrder []string
+	}{
+		{
+			name: "multiple queries with sortSeries=true - should be sorted",
+			queries: []*prompb.Query{
+				{
+					StartTimestampMs: 1000,
+					EndTimestampMs:   2000,
+					Matchers: []*prompb.LabelMatcher{
+						{Type: prompb.LabelMatcher_RE, Name: "series", Value: "ccc|bbb"}, // Returns: ccc, bbb (unsorted in store)
+					},
+				},
+				{
+					StartTimestampMs: 1500,
+					EndTimestampMs:   2500,
+					Matchers: []*prompb.LabelMatcher{
+						{Type: prompb.LabelMatcher_RE, Name: "series", Value: "aaa|bbb"}, // Returns: aaa, bbb (unsorted in store)
+					},
+				},
+			},
+			sortSeries:    true,
+			expectedOrder: []string{"aaa", "bbb", "ccc"}, // Should be sorted after merge
+		},
+		{
+			name: "multiple queries with sortSeries=false - concatenates without deduplication",
+			queries: []*prompb.Query{
+				{
+					StartTimestampMs: 1000,
+					EndTimestampMs:   2000,
+					Matchers: []*prompb.LabelMatcher{
+						{Type: prompb.LabelMatcher_RE, Name: "series", Value: "ccc|bbb"}, // Returns: ccc, bbb (unsorted)
+					},
+				},
+				{
+					StartTimestampMs: 1500,
+					EndTimestampMs:   2500,
+					Matchers: []*prompb.LabelMatcher{
+						{Type: prompb.LabelMatcher_RE, Name: "series", Value: "aaa|bbb"}, // Returns: aaa, bbb (unsorted)
+					},
+				},
+			},
+			sortSeries:    false,
+			expectedOrder: []string{"ccc", "bbb", "aaa", "bbb"}, // Concatenated results - duplicates included
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			m.reset()
+
+			result, err := m.ReadMultiple(context.Background(), tc.queries, tc.sortSeries)
+			require.NoError(t, err)
+
+			// Collect the actual results
+			var actualOrder []string
+			for result.Next() {
+				series := result.At()
+				seriesValue := series.Labels().Get("series")
+				actualOrder = append(actualOrder, seriesValue)
+			}
+			require.NoError(t, result.Err())
+
+			// Verify the expected order matches actual order
+			// For sortSeries=true: results should be in sorted order
+			// For sortSeries=false: results should be in concatenated order (with duplicates)
+			testutil.RequireEqual(t, tc.expectedOrder, actualOrder)
+		})
+	}
+}