feat: add per-tenant time sharding for long out-of-order ingestion

Author: na--

docs/sources/shared/configuration.md

@@ -3706,6 +3706,13 @@ shard_streams:
   # CLI flag: -shard-streams.enabled
   [enabled: <boolean> | default = true]
 
+  # Automatically shard streams by adding a __time_shard__ label, with values
+  # calculated from the log timestamps divided by MaxChunkAge/2. This allows the
+  # out-of-order ingestion of very old logs. If both flags are enabled,
+  # time-based sharding will happen before rate-based sharding.
+  # CLI flag: -shard-streams.time-sharding-enabled
+  [time_sharding_enabled: <boolean> | default = false]
+
   # Whether to log sharding streams behavior or not. Not recommended for
   # production environments.
   # CLI flag: -shard-streams.logging-enabled

pkg/distributor/distributor.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"math"
 	"net/http"
+	"slices"
 	"sort"
 	"strconv"
 	"strings"
@@ -64,6 +65,8 @@ const (
 	ringKey = "distributor"
 
 	ringAutoForgetUnhealthyPeriods = 2
+
+	timeShardLabel = "__time_shard__"
 )
 
 var (
@@ -132,6 +135,7 @@ type Distributor struct {
 	services.Service
 
 	cfg              Config
+	ingesterCfg      ingester.Config
 	logger           log.Logger
 	clientCfg        client.Config
 	tenantConfigs    *runtime.TenantConfigs
@@ -187,6 +191,7 @@ type Distributor struct {
 // New a distributor creates.
 func New(
 	cfg Config,
+	ingesterCfg ingester.Config,
 	clientCfg client.Config,
 	configs *runtime.TenantConfigs,
 	ingestersRing ring.ReadRing,
@@ -245,6 +250,7 @@ func New(
 
 	d := &Distributor{
 		cfg:                   cfg,
+		ingesterCfg:           ingesterCfg,
 		logger:                logger,
 		clientCfg:             clientCfg,
 		tenantConfigs:         configs,
@@ -448,6 +454,28 @@ func (d *Distributor) Push(ctx context.Context, req *logproto.PushRequest) (*log
 	var validationErrors util.GroupedErrors
 	validationContext := d.validator.getValidationContextForTime(time.Now(), tenantID)
 
+	shardStreamsCfg := d.validator.Limits.ShardStreams(tenantID)
+	maybeShardByRate := func(stream logproto.Stream, pushSize int) {
+		if shardStreamsCfg.Enabled {
+			streams = append(streams, d.shardStream(stream, pushSize, tenantID)...)
+		} else {
+			streams = append(streams, KeyedStream{
+				HashKey: lokiring.TokenFor(tenantID, stream.Labels),
+				Stream:  stream,
+			})
+		}
+	}
+	maybeShardByTime := func(stream logproto.Stream, labels labels.Labels, pushSize int) {
+		if shardStreamsCfg.TimeShardingEnabled {
+			streamsByTime := shardStreamByTime(stream, labels, d.ingesterCfg.MaxChunkAge/2)
+			for _, ts := range streamsByTime {
+				maybeShardByRate(ts.Stream, ts.linesTotalLen)
+			}
+		} else {
+			maybeShardByRate(stream, pushSize)
+		}
+	}
+
 	func() {
 		sp := opentracing.SpanFromContext(ctx)
 		if sp != nil {
@@ -456,6 +484,7 @@ func (d *Distributor) Push(ctx context.Context, req *logproto.PushRequest) (*log
 				sp.LogKV("event", "finished to validate request")
 			}()
 		}
+
 		for _, stream := range req.Streams {
 			// Return early if stream does not contain any entries
 			if len(stream.Entries) == 0 {
@@ -534,15 +563,7 @@ func (d *Distributor) Push(ctx context.Context, req *logproto.PushRequest) (*log
 				continue
 			}
 
-			shardStreamsCfg := d.validator.Limits.ShardStreams(tenantID)
-			if shardStreamsCfg.Enabled {
-				streams = append(streams, d.shardStream(stream, pushSize, tenantID)...)
-			} else {
-				streams = append(streams, KeyedStream{
-					HashKey: lokiring.TokenFor(tenantID, stream.Labels),
-					Stream:  stream,
-				})
-			}
+			maybeShardByTime(stream, lbs, pushSize)
 		}
 	}()
 
@@ -721,6 +742,52 @@ func hasAnyLevelLabels(l labels.Labels) (string, bool) {
 	return "", false
 }
 
+type streamWithTimeShard struct {
+	logproto.Stream
+	linesTotalLen int
+}
+
+// This should shard the stream into multiple sub-streams based on the log
+// timestamps, but with no new alocations for the log entries. It will sort them
+// in-place in the given stream object (so it may modify it!) and reference
+// sub-slices of the same stream.Entries slice.
+func shardStreamByTime(stream logproto.Stream, lbls labels.Labels, timeShardLen time.Duration) []streamWithTimeShard {
+	entries := stream.Entries
+	entriesLen := len(entries)
+	if entriesLen == 0 {
+		return nil
+	}
+
+	slices.SortStableFunc(entries, func(a, b logproto.Entry) int { return a.Timestamp.Compare(b.Timestamp) })
+
+	result := make([]streamWithTimeShard, 0, entries[entriesLen-1].Timestamp.Sub(entries[0].Timestamp)/timeShardLen)
+	labelBuilder := labels.NewBuilder(lbls)
+
+	for startIdx := 0; startIdx < entriesLen; /* the index is changed below */ {
+		timeShardStart := entries[startIdx].Timestamp.Truncate(timeShardLen)
+		timeShardEnd := timeShardStart.Add(timeShardLen)
+
+		endIdx := startIdx + 1
+		linesTotalLen := len(entries[startIdx].Line)
+		for ; endIdx < entriesLen && entries[endIdx].Timestamp.Before(timeShardEnd); endIdx++ {
+			linesTotalLen += len(entries[endIdx].Line)
+		}
+
+		shardLbls := labelBuilder.Set(timeShardLabel, fmt.Sprintf("%d_%d", timeShardStart.Unix(), timeShardEnd.Unix())).Labels()
+		result = append(result, streamWithTimeShard{
+			Stream: logproto.Stream{
+				Labels:  shardLbls.String(),
+				Hash:    shardLbls.Hash(),
+				Entries: stream.Entries[startIdx:endIdx],
+			},
+			linesTotalLen: linesTotalLen,
+		})
+
+		startIdx = endIdx
+	}
+	return result
+}
+
 // shardStream shards (divides) the given stream into N smaller streams, where
 // N is the sharding size for the given stream. shardSteam returns the smaller
 // streams and their associated keys for hashing to ingesters.

pkg/distributor/distributor_test.go

@@ -796,6 +796,178 @@ func TestStreamShardAcrossCalls(t *testing.T) {
 	})
 }
 
+func TestStreamShardByTime(t *testing.T) {
+	baseTimestamp := time.Date(2024, 10, 31, 12, 34, 56, 0, time.UTC)
+	t.Logf("Base timestamp: %s (unix %d)", baseTimestamp.Format(time.RFC3339Nano), baseTimestamp.Unix())
+
+	for _, tc := range []struct {
+		test         string
+		labels       string
+		entries      []logproto.Entry
+		timeShardLen time.Duration
+		expResult    []streamWithTimeShard
+	}{
+		{
+			test:         "zero shard because no entries",
+			labels:       "{app='myapp'}",
+			entries:      nil,
+			timeShardLen: time.Hour,
+			expResult:    nil,
+		},
+		{
+			test:   "single shard with one entry",
+			labels: `{app="myapp"}`,
+			entries: []logproto.Entry{
+				{Timestamp: baseTimestamp, Line: "foo"},
+				//{Timestamp: baseTimestamp.Add(time.Second), Line: "bar"},
+			},
+			timeShardLen: time.Hour,
+			expResult: []streamWithTimeShard{
+				{Stream: logproto.Stream{Labels: `{__time_shard__="1730376000_1730379600", app="myapp"}`, Entries: []logproto.Entry{
+					{Timestamp: baseTimestamp, Line: "foo"},
+				}}, linesTotalLen: 3},
+			},
+		},
+		{
+			test:   "single shard with two entries",
+			labels: `{app="myapp"}`,
+			entries: []logproto.Entry{
+				{Timestamp: baseTimestamp, Line: "foo"},
+				{Timestamp: baseTimestamp.Add(time.Second), Line: "bar"},
+			},
+			timeShardLen: time.Hour,
+			expResult: []streamWithTimeShard{
+				{Stream: logproto.Stream{Labels: `{__time_shard__="1730376000_1730379600", app="myapp"}`, Entries: []logproto.Entry{
+					{Timestamp: baseTimestamp, Line: "foo"},
+					{Timestamp: baseTimestamp.Add(time.Second), Line: "bar"},
+				}}, linesTotalLen: 6},
+			},
+		},
+		{
+			test:   "single shard with two entries reversed",
+			labels: `{app="myapp"}`,
+			entries: []logproto.Entry{
+				{Timestamp: baseTimestamp.Add(time.Second), Line: "bar"},
+				{Timestamp: baseTimestamp, Line: "foo"},
+			},
+			timeShardLen: time.Hour,
+			expResult: []streamWithTimeShard{
+				{Stream: logproto.Stream{Labels: `{__time_shard__="1730376000_1730379600", app="myapp"}`, Entries: []logproto.Entry{
+					{Timestamp: baseTimestamp, Line: "foo"},
+					{Timestamp: baseTimestamp.Add(time.Second), Line: "bar"},
+				}}, linesTotalLen: 6},
+			},
+		},
+		{
+			test:   "two shards without a gap",
+			labels: `{app="myapp"}`,
+			entries: []logproto.Entry{
+				{Timestamp: baseTimestamp, Line: "foo"},
+				{Timestamp: baseTimestamp.Add(time.Second), Line: "bar"},
+				{Timestamp: baseTimestamp.Add(time.Hour), Line: "baz"},
+			},
+			timeShardLen: time.Hour,
+			expResult: []streamWithTimeShard{
+				{Stream: logproto.Stream{Labels: `{__time_shard__="1730376000_1730379600", app="myapp"}`, Entries: []logproto.Entry{
+					{Timestamp: baseTimestamp, Line: "foo"},
+					{Timestamp: baseTimestamp.Add(time.Second), Line: "bar"},
+				}}, linesTotalLen: 6},
+				{Stream: logproto.Stream{Labels: `{__time_shard__="1730379600_1730383200", app="myapp"}`, Entries: []logproto.Entry{
+					{Timestamp: baseTimestamp.Add(time.Hour), Line: "baz"},
+				}}, linesTotalLen: 3},
+			},
+		},
+		{
+			test:   "two shards with a gap",
+			labels: `{app="myapp"}`,
+			entries: []logproto.Entry{
+				{Timestamp: baseTimestamp, Line: "foo"},
+				{Timestamp: baseTimestamp.Add(time.Second), Line: "bar"},
+				{Timestamp: baseTimestamp.Add(4 * time.Hour), Line: "baz"},
+			},
+			timeShardLen: time.Hour,
+			expResult: []streamWithTimeShard{
+				{Stream: logproto.Stream{Labels: `{__time_shard__="1730376000_1730379600", app="myapp"}`, Entries: []logproto.Entry{
+					{Timestamp: baseTimestamp, Line: "foo"},
+					{Timestamp: baseTimestamp.Add(time.Second), Line: "bar"},
+				}}, linesTotalLen: 6},
+				{Stream: logproto.Stream{Labels: `{__time_shard__="1730390400_1730394000", app="myapp"}`, Entries: []logproto.Entry{
+					{Timestamp: baseTimestamp.Add(4 * time.Hour), Line: "baz"},
+				}}, linesTotalLen: 3},
+			},
+		},
+		{
+			test:   "bigger shard len",
+			labels: `{app="myapp"}`,
+			entries: []logproto.Entry{
+				{Timestamp: baseTimestamp, Line: "foo"},
+				{Timestamp: baseTimestamp.Add(time.Second), Line: "bar"},
+				{Timestamp: baseTimestamp.Add(6 * time.Hour), Line: "baz"},
+			},
+			timeShardLen: 24 * time.Hour,
+			expResult: []streamWithTimeShard{
+				{Stream: logproto.Stream{Labels: `{__time_shard__="1730332800_1730419200", app="myapp"}`, Entries: []logproto.Entry{
+					{Timestamp: baseTimestamp, Line: "foo"},
+					{Timestamp: baseTimestamp.Add(time.Second), Line: "bar"},
+					{Timestamp: baseTimestamp.Add(6 * time.Hour), Line: "baz"},
+				}}, linesTotalLen: 9},
+			},
+		},
+		{
+			test:   "longer messy gaps",
+			labels: `{app="myapp"}`,
+			entries: []logproto.Entry{
+				{Timestamp: baseTimestamp.Truncate(time.Hour), Line: "11"},
+				{Timestamp: baseTimestamp, Line: "13"},
+				{Timestamp: baseTimestamp, Line: "14"},
+				{Timestamp: baseTimestamp.Truncate(time.Hour), Line: "12"},
+				{Timestamp: baseTimestamp.Add(2 * time.Hour), Line: "32"},
+				{Timestamp: baseTimestamp.Truncate(time.Hour).Add(2 * time.Hour), Line: "31"},
+				{Timestamp: baseTimestamp.Add(5 * time.Hour), Line: "41"},
+				{Timestamp: baseTimestamp.Truncate(time.Hour).Add(time.Hour), Line: "21"},
+			},
+			timeShardLen: time.Hour,
+			expResult: []streamWithTimeShard{
+				{Stream: logproto.Stream{Labels: `{__time_shard__="1730376000_1730379600", app="myapp"}`, Entries: []logproto.Entry{
+					{Timestamp: baseTimestamp.Truncate(time.Hour), Line: "11"},
+					{Timestamp: baseTimestamp.Truncate(time.Hour), Line: "12"},
+					{Timestamp: baseTimestamp, Line: "13"},
+					{Timestamp: baseTimestamp, Line: "14"},
+				}}, linesTotalLen: 8},
+				{Stream: logproto.Stream{Labels: `{__time_shard__="1730379600_1730383200", app="myapp"}`, Entries: []logproto.Entry{
+					{Timestamp: baseTimestamp.Truncate(time.Hour).Add(time.Hour), Line: "21"},
+				}}, linesTotalLen: 2},
+				{Stream: logproto.Stream{Labels: `{__time_shard__="1730383200_1730386800", app="myapp"}`, Entries: []logproto.Entry{
+					{Timestamp: baseTimestamp.Truncate(time.Hour).Add(2 * time.Hour), Line: "31"},
+					{Timestamp: baseTimestamp.Add(2 * time.Hour), Line: "32"},
+				}}, linesTotalLen: 4},
+				{Stream: logproto.Stream{Labels: `{__time_shard__="1730394000_1730397600", app="myapp"}`, Entries: []logproto.Entry{
+					{Timestamp: baseTimestamp.Add(5 * time.Hour), Line: "41"},
+				}}, linesTotalLen: 2},
+			},
+		},
+	} {
+		t.Run(tc.test, func(t *testing.T) {
+			lbls, err := syntax.ParseLabels(tc.labels)
+			require.NoError(t, err)
+			stream := logproto.Stream{
+				Labels:  tc.labels,
+				Hash:    lbls.Hash(),
+				Entries: tc.entries,
+			}
+
+			shardedStreams := shardStreamByTime(stream, lbls, tc.timeShardLen)
+			require.Len(t, shardedStreams, len(tc.expResult))
+
+			for i, ss := range shardedStreams {
+				assert.Equal(t, tc.expResult[i].linesTotalLen, ss.linesTotalLen)
+				assert.Equal(t, tc.expResult[i].Labels, ss.Labels)
+				assert.EqualValues(t, tc.expResult[i].Entries, ss.Entries)
+			}
+		})
+	}
+}
+
 func generateEntries(n int) []logproto.Entry {
 	var entries []logproto.Entry
 	for i := 0; i < n; i++ {
@@ -1386,7 +1558,9 @@ func prepare(t *testing.T, numDistributors, numIngesters int, limits *validation
 		overrides, err := validation.NewOverrides(*limits, nil)
 		require.NoError(t, err)
 
-		d, err := New(distributorConfig, clientConfig, runtime.DefaultTenantConfigs(), ingestersRing, partitionRingReader, overrides, prometheus.NewPedanticRegistry(), constants.Loki, nil, nil, log.NewNopLogger())
+		ingesterConfig := ingester.Config{MaxChunkAge: 2 * time.Hour}
+
+		d, err := New(distributorConfig, ingesterConfig, clientConfig, runtime.DefaultTenantConfigs(), ingestersRing, partitionRingReader, overrides, prometheus.NewPedanticRegistry(), constants.Loki, nil, nil, log.NewNopLogger())
 		require.NoError(t, err)
 		require.NoError(t, services.StartAndAwaitRunning(context.Background(), d))
 		distributors[i] = d

pkg/distributor/shardstreams/config.go

@@ -9,6 +9,8 @@ import (
 type Config struct {
 	Enabled bool `yaml:"enabled" json:"enabled" doc:"description=Automatically shard streams to keep them under the per-stream rate limit. Sharding is dictated by the desired rate."`
 
+	TimeShardingEnabled bool `yaml:"time_sharding_enabled" json:"time_sharding_enabled" doc:"description=Automatically shard streams by adding a __time_shard__ label, with values calculated from the log timestamps divided by MaxChunkAge/2. This allows the out-of-order ingestion of very old logs. If both flags are enabled, time-based sharding will happen before rate-based sharding."`
+
 	LoggingEnabled bool `yaml:"logging_enabled" json:"logging_enabled" doc:"description=Whether to log sharding streams behavior or not. Not recommended for production environments."`
 
 	// DesiredRate is the threshold used to shard the stream into smaller pieces.
@@ -18,6 +20,7 @@ type Config struct {
 
 func (cfg *Config) RegisterFlagsWithPrefix(prefix string, fs *flag.FlagSet) {
 	fs.BoolVar(&cfg.Enabled, prefix+".enabled", true, "Automatically shard streams to keep them under the per-stream rate limit")
+	fs.BoolVar(&cfg.TimeShardingEnabled, prefix+".time-sharding-enabled", false, "Automatically shard streams by time (in MaxChunkAge/2 buckets), to allow out-of-order ingestion of very old logs.")
 	fs.BoolVar(&cfg.LoggingEnabled, prefix+".logging-enabled", false, "Enable logging when sharding streams")
 	cfg.DesiredRate.Set("1536KB") //nolint:errcheck
 	fs.Var(&cfg.DesiredRate, prefix+".desired-rate", "threshold used to cut a new shard. Default (1536KB) means if a rate is above 1536KB/s, it will be sharded.")

pkg/loki/modules.go

@@ -330,6 +330,7 @@ func (t *Loki) initDistributor() (services.Service, error) {
 	logger := log.With(util_log.Logger, "component", "distributor")
 	t.distributor, err = distributor.New(
 		t.Cfg.Distributor,
+		t.Cfg.Ingester,
 		t.Cfg.IngesterClient,
 		t.tenantConfigs,
 		t.ring,