diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3f9811f23d..da6a08fff3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,7 @@ We use *breaking :warning:* to mark changes that are not backward compatible (re
 
 - [#6692](https://github.com/thanos-io/thanos/pull/6692) Store: Fix matching bug when using empty alternative in regex matcher, for example (a||b).
 - [#6679](https://github.com/thanos-io/thanos/pull/6697) Store: fix block deduplication
+- [#6706](https://github.com/thanos-io/thanos/pull/6706) Store: Series responses should always be sorted
 
 ### Added
 
diff --git a/cmd/thanos/receive.go b/cmd/thanos/receive.go
index 8d37f42c23..5b699d264d 100644
--- a/cmd/thanos/receive.go
+++ b/cmd/thanos/receive.go
@@ -366,21 +366,6 @@ func runReceive(
 			grpcserver.WithTLSConfig(tlsCfg),
 		)
 
-		ctx, cancel := context.WithCancel(context.Background())
-		level.Debug(logger).Log("msg", "setting up periodic update for label names")
-		g.Add(func() error {
-			return runutil.Repeat(10*time.Second, ctx.Done(), func() error {
-				level.Debug(logger).Log("msg", "Starting label names update")
-
-				dbs.UpdateLabelNames(ctx)
-
-				level.Debug(logger).Log("msg", "Finished label names update")
-				return nil
-			})
-		}, func(err error) {
-			cancel()
-		})
-
 		g.Add(
 			func() error {
 				level.Info(logger).Log("msg", "listening for StoreAPI and WritableStoreAPI gRPC", "address", conf.grpcConfig.bindAddress)
diff --git a/cmd/thanos/rule.go b/cmd/thanos/rule.go
index 2d519185a3..ceadf1159c 100644
--- a/cmd/thanos/rule.go
+++ b/cmd/thanos/rule.go
@@ -656,21 +656,6 @@ func runRule(
 		)
 		storeServer := store.NewLimitedStoreServer(store.NewInstrumentedStoreServer(reg, tsdbStore), reg, conf.storeRateLimits)
 		options = append(options, grpcserver.WithServer(store.RegisterStoreServer(storeServer, logger)))
-
-		ctx, cancel := context.WithCancel(context.Background())
-		level.Debug(logger).Log("msg", "setting up periodic update for label names")
-		g.Add(func() error {
-			return runutil.Repeat(10*time.Second, ctx.Done(), func() error {
-				level.Debug(logger).Log("msg", "Starting label names update")
-
-				tsdbStore.UpdateLabelNames(ctx)
-
-				level.Debug(logger).Log("msg", "Finished label names update")
-				return nil
-			})
-		}, func(err error) {
-			cancel()
-		})
 	}
 
 	options = append(options, grpcserver.WithServer(
diff --git a/cmd/thanos/sidecar.go b/cmd/thanos/sidecar.go
index 968a09ee9c..27cf759b2a 100644
--- a/cmd/thanos/sidecar.go
+++ b/cmd/thanos/sidecar.go
@@ -48,7 +48,6 @@ import (
 	"github.com/thanos-io/thanos/pkg/shipper"
 	"github.com/thanos-io/thanos/pkg/store"
 	"github.com/thanos-io/thanos/pkg/store/labelpb"
-	"github.com/thanos-io/thanos/pkg/stringset"
 	"github.com/thanos-io/thanos/pkg/targets"
 	"github.com/thanos-io/thanos/pkg/tls"
 )
@@ -113,9 +112,8 @@ func runSidecar(
 		mint: conf.limitMinTime.PrometheusTimestamp(),
 		maxt: math.MaxInt64,
 
-		limitMinTime:  conf.limitMinTime,
-		client:        promclient.NewWithTracingClient(logger, httpClient, "thanos-sidecar"),
-		labelNamesSet: stringset.AllStrings(),
+		limitMinTime: conf.limitMinTime,
+		client:       promclient.NewWithTracingClient(logger, httpClient, "thanos-sidecar"),
 	}
 
 	confContentYaml, err := conf.objStore.Content()
@@ -239,19 +237,6 @@ func runSidecar(
 		}, func(error) {
 			cancel()
 		})
-
-		g.Add(func() error {
-			return runutil.Repeat(10*time.Second, ctx.Done(), func() error {
-				level.Debug(logger).Log("msg", "Starting label names update")
-
-				m.UpdateLabelNames(context.Background())
-
-				level.Debug(logger).Log("msg", "Finished label names update")
-				return nil
-			})
-		}, func(err error) {
-			cancel()
-		})
 	}
 	{
 		ctx, cancel := context.WithCancel(context.Background())
@@ -264,7 +249,7 @@ func runSidecar(
 	{
 		c := promclient.NewWithTracingClient(logger, httpClient, httpconfig.ThanosUserAgent)
 
-		promStore, err := store.NewPrometheusStore(logger, reg, c, conf.prometheus.url, component.Sidecar, m.Labels, m.Timestamps, m.LabelNamesSet, m.Version)
+		promStore, err := store.NewPrometheusStore(logger, reg, c, conf.prometheus.url, component.Sidecar, m.Labels, m.Timestamps, m.Version)
 		if err != nil {
 			return errors.Wrap(err, "create Prometheus store")
 		}
@@ -434,8 +419,6 @@ type promMetadata struct {
 	limitMinTime thanosmodel.TimeOrDurationValue
 
 	client *promclient.Client
-
-	labelNamesSet stringset.Set
 }
 
 func (s *promMetadata) UpdateLabels(ctx context.Context) error {
@@ -463,30 +446,6 @@ func (s *promMetadata) UpdateTimestamps(mint, maxt int64) {
 	s.maxt = maxt
 }
 
-func (s *promMetadata) UpdateLabelNames(ctx context.Context) {
-	mint, _ := s.Timestamps()
-	labelNames, err := s.client.LabelNamesInGRPC(ctx, s.promURL, nil, mint, time.Now().UnixMilli())
-	if err != nil {
-		s.mtx.Lock()
-		defer s.mtx.Unlock()
-
-		s.labelNamesSet = stringset.AllStrings()
-		return
-	}
-
-	filter := stringset.NewFromStrings(labelNames...)
-	s.mtx.Lock()
-	s.labelNamesSet = filter
-	s.mtx.Unlock()
-}
-
-func (s *promMetadata) LabelNamesSet() stringset.Set {
-	s.mtx.Lock()
-	defer s.mtx.Unlock()
-
-	return s.labelNamesSet
-}
-
 func (s *promMetadata) Labels() labels.Labels {
 	s.mtx.Lock()
 	defer s.mtx.Unlock()
diff --git a/cmd/thanos/store.go b/cmd/thanos/store.go
index 29ac6921a2..73e4b838dd 100644
--- a/cmd/thanos/store.go
+++ b/cmd/thanos/store.go
@@ -501,23 +501,6 @@ func runStore(
 		})
 	}
 
-	{
-		ctx, cancel := context.WithCancel(context.Background())
-		level.Debug(logger).Log("msg", "setting up periodic update for label names")
-		g.Add(func() error {
-			return runutil.Repeat(10*time.Second, ctx.Done(), func() error {
-				level.Debug(logger).Log("msg", "Starting label names update")
-
-				bs.UpdateLabelNames()
-
-				level.Debug(logger).Log("msg", "Finished label names update")
-				return nil
-			})
-		}, func(err error) {
-			cancel()
-		})
-
-	}
 	// Add bucket UI for loaded blocks.
 	{
 		ins := extpromhttp.NewInstrumentationMiddleware(reg, nil)
diff --git a/go.mod b/go.mod
index b9b2c27d22..404442782e 100644
--- a/go.mod
+++ b/go.mod
@@ -118,14 +118,12 @@ require (
 
 require (
 	github.com/onsi/gomega v1.27.10
-	github.com/seiflotfy/cuckoofilter v0.0.0-20220411075957-e3b120b3f5fb
 	go.opentelemetry.io/contrib/propagators/autoprop v0.38.0
 	go4.org/intern v0.0.0-20230525184215-6c62f75575cb
 	golang.org/x/exp v0.0.0-20230713183714-613f0c0eb8a1
 )
 
 require (
-	github.com/dgryski/go-metro v0.0.0-20200812162917-85c65e2d0165 // indirect
 	github.com/golang-jwt/jwt/v5 v5.0.0 // indirect
 	github.com/google/s2a-go v0.1.4 // indirect
 	github.com/huaweicloud/huaweicloud-sdk-go-obs v3.23.3+incompatible // indirect
diff --git a/go.sum b/go.sum
index b18e2af8d2..2f61a3076b 100644
--- a/go.sum
+++ b/go.sum
@@ -223,8 +223,6 @@ github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc/go.mod h1:J7Y8Yc
 github.com/dennwc/varint v1.0.0 h1:kGNFFSSw8ToIy3obO/kKr8U9GZYUAxQEVuix4zfDWzE=
 github.com/dennwc/varint v1.0.0/go.mod h1:hnItb35rvZvJrbTALZtY/iQfDs48JKRG1RPpgziApxA=
 github.com/dgrijalva/jwt-go v3.2.0+incompatible/go.mod h1:E3ru+11k8xSBh+hMPgOLZmtrrCbhqsmaPHjLKYnJCaQ=
-github.com/dgryski/go-metro v0.0.0-20200812162917-85c65e2d0165 h1:BS21ZUJ/B5X2UVUbczfmdWH7GapPWAhxcMsDnjJTU1E=
-github.com/dgryski/go-metro v0.0.0-20200812162917-85c65e2d0165/go.mod h1:c9O8+fpSOX1DM8cPNSkX/qsBWdkD4yd2dpciOWQjpBw=
 github.com/digitalocean/godo v1.99.0 h1:gUHO7n9bDaZFWvbzOum4bXE0/09ZuYA9yA8idQHX57E=
 github.com/dnaeon/go-vcr v1.2.0 h1:zHCHvJYTMh1N7xnV7zf1m1GPBF9Ad0Jk/whtQ1663qI=
 github.com/docker/distribution v2.8.2+incompatible h1:T3de5rq0dB1j30rp0sA2rER+m322EBzniBPB6ZIzuh8=
@@ -851,8 +849,6 @@ github.com/santhosh-tekuri/jsonschema v1.2.4/go.mod h1:TEAUOeZSmIxTTuHatJzrvARHi
 github.com/satori/go.uuid v1.2.1-0.20181028125025-b2ce2384e17b h1:gQZ0qzfKHQIybLANtM3mBXNUtOfsCFXeTsnBqCsx1KM=
 github.com/scaleway/scaleway-sdk-go v1.0.0-beta.20 h1:a9hSJdJcd16e0HoMsnFvaHvxB3pxSD+SC7+CISp7xY0=
 github.com/sean-/seed v0.0.0-20170313163322-e2103e2c3529/go.mod h1:DxrIzT+xaE7yg65j358z/aeFdxmN0P9QXhEzd20vsDc=
-github.com/seiflotfy/cuckoofilter v0.0.0-20220411075957-e3b120b3f5fb h1:XfLJSPIOUX+osiMraVgIrMR27uMXnRJWGm1+GL8/63U=
-github.com/seiflotfy/cuckoofilter v0.0.0-20220411075957-e3b120b3f5fb/go.mod h1:bR6DqgcAl1zTcOX8/pE2Qkj9XO00eCNqmKb7lXP8EAg=
 github.com/sercand/kuberesolver v2.4.0+incompatible h1:WE2OlRf6wjLxHwNkkFLQGaZcVLEXjMjBPjjEU5vksH8=
 github.com/sercand/kuberesolver v2.4.0+incompatible/go.mod h1:lWF3GL0xptCB/vCiJPl/ZshwPsX/n4Y7u0CW9E7aQIQ=
 github.com/shirou/gopsutil/v3 v3.21.2/go.mod h1:ghfMypLDrFSWN2c9cDYFLHyynQ+QUht0cv/18ZqVczw=
diff --git a/pkg/receive/multitsdb.go b/pkg/receive/multitsdb.go
index 4dadb97343..509e9f3535 100644
--- a/pkg/receive/multitsdb.go
+++ b/pkg/receive/multitsdb.go
@@ -867,19 +867,6 @@ func (t *MultiTSDB) extractTenantsLabels(tenantID string, initialLset labels.Lab
 	return initialLset, nil
 }
 
-func (t *MultiTSDB) UpdateLabelNames(ctx context.Context) {
-	t.mtx.RLock()
-	defer t.mtx.RUnlock()
-
-	for _, tenant := range t.tenants {
-		db := tenant.storeTSDB
-		if db == nil {
-			continue
-		}
-		db.UpdateLabelNames(ctx)
-	}
-}
-
 // extendLabels extends external labels of the initial label set.
 // If an external label shares same name with a label in the initial label set,
 // use the label in the initial label set and inform user about it.
diff --git a/pkg/store/acceptance_test.go b/pkg/store/acceptance_test.go
index 2d5a7aebfd..c22c27bf3c 100644
--- a/pkg/store/acceptance_test.go
+++ b/pkg/store/acceptance_test.go
@@ -28,7 +28,6 @@ import (
 	"github.com/thanos-io/thanos/pkg/component"
 	"github.com/thanos-io/thanos/pkg/promclient"
 	"github.com/thanos-io/thanos/pkg/store/storepb"
-	"github.com/thanos-io/thanos/pkg/stringset"
 	"github.com/thanos-io/thanos/pkg/testutil/custom"
 	"github.com/thanos-io/thanos/pkg/testutil/e2eutil"
 )
@@ -827,7 +826,6 @@ func TestPrometheusStore_Acceptance(t *testing.T) {
 		promStore, err := NewPrometheusStore(nil, nil, promclient.NewDefaultClient(), u, component.Sidecar,
 			func() labels.Labels { return extLset },
 			func() (int64, int64) { return timestamp.FromTime(minTime), timestamp.FromTime(maxTime) },
-			func() stringset.Set { return stringset.AllStrings() },
 			func() string { return version })
 		testutil.Ok(tt, err)
 
diff --git a/pkg/store/bucket.go b/pkg/store/bucket.go
index e6ec63d019..54150d178a 100644
--- a/pkg/store/bucket.go
+++ b/pkg/store/bucket.go
@@ -59,7 +59,6 @@ import (
 	"github.com/thanos-io/thanos/pkg/store/hintspb"
 	"github.com/thanos-io/thanos/pkg/store/labelpb"
 	"github.com/thanos-io/thanos/pkg/store/storepb"
-	"github.com/thanos-io/thanos/pkg/stringset"
 	"github.com/thanos-io/thanos/pkg/strutil"
 	"github.com/thanos-io/thanos/pkg/tenancy"
 	"github.com/thanos-io/thanos/pkg/tracing"
@@ -387,9 +386,6 @@ type BucketStore struct {
 
 	enabledLazyExpandedPostings bool
 
-	bmtx          sync.Mutex
-	labelNamesSet stringset.Set
-
 	blockEstimatedMaxSeriesFunc BlockEstimator
 	blockEstimatedMaxChunkFunc  BlockEstimator
 }
@@ -543,7 +539,6 @@ func NewBucketStore(
 		enableSeriesResponseHints:   enableSeriesResponseHints,
 		enableChunkHashCalculation:  enableChunkHashCalculation,
 		seriesBatchSize:             SeriesBatchSize,
-		labelNamesSet:               stringset.AllStrings(),
 	}
 
 	for _, option := range options {
@@ -1790,38 +1785,6 @@ func (s *BucketStore) LabelNames(ctx context.Context, req *storepb.LabelNamesReq
 	}, nil
 }
 
-func (s *BucketStore) UpdateLabelNames() {
-	s.mtx.RLock()
-	defer s.mtx.RUnlock()
-
-	newSet := stringset.New()
-	for _, b := range s.blocks {
-		labelNames, err := b.indexHeaderReader.LabelNames()
-		if err != nil {
-			level.Warn(s.logger).Log("msg", "error getting label names", "block", b.meta.ULID, "err", err.Error())
-			s.updateLabelNamesSet(stringset.AllStrings())
-			return
-		}
-		for _, l := range labelNames {
-			newSet.Insert(l)
-		}
-	}
-	s.updateLabelNamesSet(newSet)
-}
-
-func (s *BucketStore) updateLabelNamesSet(newSet stringset.Set) {
-	s.bmtx.Lock()
-	s.labelNamesSet = newSet
-	s.bmtx.Unlock()
-}
-
-func (b *BucketStore) LabelNamesSet() stringset.Set {
-	b.bmtx.Lock()
-	defer b.bmtx.Unlock()
-
-	return b.labelNamesSet
-}
-
 func (b *bucketBlock) FilterExtLabelsMatchers(matchers []*labels.Matcher) ([]*labels.Matcher, bool) {
 	// We filter external labels from matchers so we won't try to match series on them.
 	var result []*labels.Matcher
diff --git a/pkg/store/bucket_e2e_test.go b/pkg/store/bucket_e2e_test.go
index 7262dee155..ebd1ffa709 100644
--- a/pkg/store/bucket_e2e_test.go
+++ b/pkg/store/bucket_e2e_test.go
@@ -779,30 +779,6 @@ func TestBucketStore_LabelNames_e2e(t *testing.T) {
 	})
 }
 
-func TestBucketStore_LabelNamesSet_e2e(t *testing.T) {
-	objtesting.ForeachStore(t, func(t *testing.T, bkt objstore.Bucket) {
-		dir := t.TempDir()
-
-		s := prepareStoreWithTestBlocks(t, dir, bkt, false, NewChunksLimiterFactory(0), NewSeriesLimiterFactory(0), NewBytesLimiterFactory(0), emptyRelabelConfig, allowAllFilterConf)
-		s.cache.SwapWith(noopCache{})
-
-		mint, maxt := s.store.TimeRange()
-		testutil.Equals(t, s.minTime, mint)
-		testutil.Equals(t, s.maxTime, maxt)
-
-		s.store.UpdateLabelNames()
-		for _, b := range s.store.blocks {
-			waitTimeout(t, &b.pendingReaders, 5*time.Second)
-		}
-
-		filter := s.store.LabelNamesSet()
-		for _, n := range []string{"a", "b", "c"} {
-			testutil.Assert(t, filter.Has(n), "expected filter to have %s", n)
-		}
-		testutil.Equals(t, 3, filter.Count())
-	})
-}
-
 func TestBucketStore_LabelNames_SeriesLimiter_e2e(t *testing.T) {
 	cases := map[string]struct {
 		maxSeriesLimit uint64
diff --git a/pkg/store/bucket_test.go b/pkg/store/bucket_test.go
index 50ead2c36f..846fea2e98 100644
--- a/pkg/store/bucket_test.go
+++ b/pkg/store/bucket_test.go
@@ -61,7 +61,6 @@ import (
 	"github.com/thanos-io/thanos/pkg/store/labelpb"
 	"github.com/thanos-io/thanos/pkg/store/storepb"
 	storetestutil "github.com/thanos-io/thanos/pkg/store/storepb/testutil"
-	"github.com/thanos-io/thanos/pkg/stringset"
 	"github.com/thanos-io/thanos/pkg/testutil/custom"
 	"github.com/thanos-io/thanos/pkg/testutil/e2eutil"
 )
@@ -1661,7 +1660,6 @@ func TestBucketSeries_OneBlock_InMemIndexCacheSegfault(t *testing.T) {
 		chunksLimiterFactory: NewChunksLimiterFactory(0),
 		seriesLimiterFactory: NewSeriesLimiterFactory(0),
 		bytesLimiterFactory:  NewBytesLimiterFactory(0),
-		labelNamesSet:        stringset.AllStrings(),
 	}
 
 	t.Run("invoke series for one block. Fill the cache on the way.", func(t *testing.T) {
@@ -3471,9 +3469,6 @@ func TestBucketStoreDedupOnBlockSeriesSet(t *testing.T) {
 
 	testutil.Ok(t, bucketStore.SyncBlocks(context.Background()))
 
-	// make sure to have updated inner label names
-	bucketStore.UpdateLabelNames()
-
 	srv := newStoreSeriesServer(context.Background())
 	testutil.Ok(t, bucketStore.Series(&storepb.SeriesRequest{
 		WithoutReplicaLabels: []string{"replica"},
diff --git a/pkg/store/prometheus.go b/pkg/store/prometheus.go
index 308a0741ce..fd6d4c0195 100644
--- a/pkg/store/prometheus.go
+++ b/pkg/store/prometheus.go
@@ -42,7 +42,6 @@ import (
 	"github.com/thanos-io/thanos/pkg/store/labelpb"
 	"github.com/thanos-io/thanos/pkg/store/storepb"
 	"github.com/thanos-io/thanos/pkg/store/storepb/prompb"
-	"github.com/thanos-io/thanos/pkg/stringset"
 	"github.com/thanos-io/thanos/pkg/tracing"
 )
 
@@ -54,7 +53,6 @@ type PrometheusStore struct {
 	buffers          sync.Pool
 	component        component.StoreAPI
 	externalLabelsFn func() labels.Labels
-	labelNamesSet    func() stringset.Set
 
 	promVersion func() string
 	timestamps  func() (mint int64, maxt int64)
@@ -81,7 +79,6 @@ func NewPrometheusStore(
 	component component.StoreAPI,
 	externalLabelsFn func() labels.Labels,
 	timestamps func() (mint int64, maxt int64),
-	labelNamesSet func() stringset.Set,
 	promVersion func() string,
 ) (*PrometheusStore, error) {
 	if logger == nil {
@@ -95,7 +92,6 @@ func NewPrometheusStore(
 		externalLabelsFn:              externalLabelsFn,
 		promVersion:                   promVersion,
 		timestamps:                    timestamps,
-		labelNamesSet:                 labelNamesSet,
 		remoteReadAcceptableResponses: []prompb.ReadRequest_ResponseType{prompb.ReadRequest_STREAMED_XOR_CHUNKS, prompb.ReadRequest_SAMPLES},
 		buffers: sync.Pool{New: func() interface{} {
 			b := make([]byte, 0, initialBufSize)
diff --git a/pkg/store/prometheus_test.go b/pkg/store/prometheus_test.go
index 82965672c7..d0597b6e9c 100644
--- a/pkg/store/prometheus_test.go
+++ b/pkg/store/prometheus_test.go
@@ -26,7 +26,6 @@ import (
 	"github.com/thanos-io/thanos/pkg/store/labelpb"
 	"github.com/thanos-io/thanos/pkg/store/storepb"
 	"github.com/thanos-io/thanos/pkg/store/storepb/prompb"
-	"github.com/thanos-io/thanos/pkg/stringset"
 	"github.com/thanos-io/thanos/pkg/testutil/custom"
 	"github.com/thanos-io/thanos/pkg/testutil/e2eutil"
 )
@@ -72,7 +71,6 @@ func testPrometheusStoreSeriesE2e(t *testing.T, prefix string) {
 	proxy, err := NewPrometheusStore(nil, nil, promclient.NewDefaultClient(), u, component.Sidecar,
 		func() labels.Labels { return labels.FromStrings("region", "eu-west") },
 		func() (int64, int64) { return limitMinT, -1 },
-		func() stringset.Set { return stringset.AllStrings() },
 		nil,
 	) // MaxTime does not matter.
 	testutil.Ok(t, err)
@@ -234,7 +232,6 @@ func TestPrometheusStore_SeriesLabels_e2e(t *testing.T) {
 	promStore, err := NewPrometheusStore(nil, nil, promclient.NewDefaultClient(), u, component.Sidecar,
 		func() labels.Labels { return labels.FromStrings("region", "eu-west") },
 		func() (int64, int64) { return math.MinInt64/1000 + 62135596801, math.MaxInt64/1000 - 62135596801 },
-		func() stringset.Set { return stringset.AllStrings() },
 		nil,
 	)
 	testutil.Ok(t, err)
@@ -417,7 +414,6 @@ func TestPrometheusStore_Series_MatchExternalLabel(t *testing.T) {
 	proxy, err := NewPrometheusStore(nil, nil, promclient.NewDefaultClient(), u, component.Sidecar,
 		func() labels.Labels { return labels.FromStrings("region", "eu-west") },
 		func() (int64, int64) { return 0, math.MaxInt64 },
-		func() stringset.Set { return stringset.AllStrings() },
 		nil)
 	testutil.Ok(t, err)
 	srv := newStoreSeriesServer(ctx)
@@ -481,7 +477,6 @@ func TestPrometheusStore_Series_ChunkHashCalculation_Integration(t *testing.T) {
 	proxy, err := NewPrometheusStore(nil, nil, promclient.NewDefaultClient(), u, component.Sidecar,
 		func() labels.Labels { return labels.FromStrings("region", "eu-west") },
 		func() (int64, int64) { return 0, math.MaxInt64 },
-		func() stringset.Set { return stringset.AllStrings() },
 		nil)
 	testutil.Ok(t, err)
 	srv := newStoreSeriesServer(ctx)
@@ -512,7 +507,6 @@ func TestPrometheusStore_Info(t *testing.T) {
 	proxy, err := NewPrometheusStore(nil, nil, promclient.NewDefaultClient(), nil, component.Sidecar,
 		func() labels.Labels { return labels.FromStrings("region", "eu-west") },
 		func() (int64, int64) { return 123, 456 },
-		func() stringset.Set { return stringset.AllStrings() },
 		nil)
 	testutil.Ok(t, err)
 
@@ -592,7 +586,6 @@ func TestPrometheusStore_Series_SplitSamplesIntoChunksWithMaxSizeOf120(t *testin
 		proxy, err := NewPrometheusStore(nil, nil, promclient.NewDefaultClient(), u, component.Sidecar,
 			func() labels.Labels { return labels.FromStrings("region", "eu-west") },
 			func() (int64, int64) { return 0, math.MaxInt64 },
-			func() stringset.Set { return stringset.AllStrings() },
 			nil)
 		testutil.Ok(t, err)
 
diff --git a/pkg/store/tsdb.go b/pkg/store/tsdb.go
index 37badaf1dc..b5182f3008 100644
--- a/pkg/store/tsdb.go
+++ b/pkg/store/tsdb.go
@@ -13,7 +13,6 @@ import (
 	"sync"
 
 	"github.com/go-kit/log"
-	"github.com/go-kit/log/level"
 	"github.com/pkg/errors"
 	"github.com/prometheus/prometheus/model/labels"
 	"github.com/prometheus/prometheus/storage"
@@ -26,7 +25,6 @@ import (
 	"github.com/thanos-io/thanos/pkg/runutil"
 	"github.com/thanos-io/thanos/pkg/store/labelpb"
 	"github.com/thanos-io/thanos/pkg/store/storepb"
-	"github.com/thanos-io/thanos/pkg/stringset"
 )
 
 const RemoteReadFrameLimit = 1048576
@@ -46,9 +44,6 @@ type TSDBStore struct {
 	buffers          sync.Pool
 	maxBytesPerFrame int
 
-	lmx           sync.RWMutex
-	labelNamesSet stringset.Set
-
 	extLset labels.Labels
 	mtx     sync.RWMutex
 }
@@ -77,7 +72,6 @@ func NewTSDBStore(logger log.Logger, db TSDBReader, component component.StoreAPI
 		component:        component,
 		extLset:          extLset,
 		maxBytesPerFrame: RemoteReadFrameLimit,
-		labelNamesSet:    stringset.AllStrings(),
 		buffers: sync.Pool{New: func() interface{} {
 			b := make([]byte, 0, initialBufSize)
 			return &b
@@ -376,38 +370,3 @@ func (s *TSDBStore) LabelValues(ctx context.Context, r *storepb.LabelValuesReque
 
 	return &storepb.LabelValuesResponse{Values: values}, nil
 }
-
-func (s *TSDBStore) UpdateLabelNames(ctx context.Context) {
-	newSet := stringset.New()
-	q, err := s.db.ChunkQuerier(ctx, math.MinInt64, math.MaxInt64)
-	if err != nil {
-		level.Warn(s.logger).Log("msg", "error creating tsdb querier", "err", err.Error())
-		s.setLabelNamesSet(stringset.AllStrings())
-		return
-	}
-	defer runutil.CloseWithLogOnErr(s.logger, q, "close tsdb querier label names")
-
-	res, _, err := q.LabelNames()
-	if err != nil {
-		level.Warn(s.logger).Log("msg", "error getting label names", "err", err.Error())
-		s.setLabelNamesSet(stringset.AllStrings())
-		return
-	}
-	for _, l := range res {
-		newSet.Insert(l)
-	}
-	s.setLabelNamesSet(newSet)
-}
-
-func (s *TSDBStore) setLabelNamesSet(newSet stringset.Set) {
-	s.lmx.Lock()
-	s.labelNamesSet = newSet
-	s.lmx.Unlock()
-}
-
-func (b *TSDBStore) LabelNamesSet() stringset.Set {
-	b.lmx.RLock()
-	defer b.lmx.RUnlock()
-
-	return b.labelNamesSet
-}
diff --git a/pkg/stringset/set.go b/pkg/stringset/set.go
deleted file mode 100644
index 080071570f..0000000000
--- a/pkg/stringset/set.go
+++ /dev/null
@@ -1,101 +0,0 @@
-// Copyright (c) The Thanos Authors.
-// Licensed under the Apache License 2.0.
-
-package stringset
-
-import (
-	cuckoo "github.com/seiflotfy/cuckoofilter"
-)
-
-type Set interface {
-	Has(string) bool
-	HasAny([]string) bool
-	// Count returns the number of elements in the set.
-	// A value of -1 indicates infinite size and can be returned by a
-	// set representing all possible string values.
-	Count() int
-}
-
-type fixedSet struct {
-	cuckoo *cuckoo.Filter
-}
-
-func (f fixedSet) HasAny(strings []string) bool {
-	for _, s := range strings {
-		if f.Has(s) {
-			return true
-		}
-	}
-	return false
-}
-
-func NewFromStrings(items ...string) Set {
-	f := cuckoo.NewFilter(uint(len(items)))
-	for _, label := range items {
-		f.InsertUnique([]byte(label))
-	}
-
-	return &fixedSet{cuckoo: f}
-}
-
-func (f fixedSet) Has(s string) bool {
-	return f.cuckoo.Lookup([]byte(s))
-}
-
-func (f fixedSet) Count() int {
-	return int(f.cuckoo.Count())
-}
-
-type mutableSet struct {
-	cuckoo *cuckoo.ScalableCuckooFilter
-}
-
-type MutableSet interface {
-	Set
-	Insert(string)
-}
-
-func New() MutableSet {
-	return &mutableSet{
-		cuckoo: cuckoo.NewScalableCuckooFilter(),
-	}
-}
-
-func (e mutableSet) Insert(s string) {
-	e.cuckoo.InsertUnique([]byte(s))
-}
-
-func (e mutableSet) Has(s string) bool {
-	return e.cuckoo.Lookup([]byte(s))
-}
-
-func (e mutableSet) HasAny(strings []string) bool {
-	for _, s := range strings {
-		if e.Has(s) {
-			return true
-		}
-	}
-	return false
-}
-
-func (e mutableSet) Count() int {
-	return int(e.cuckoo.Count())
-}
-
-type allStringsSet struct{}
-
-func (e allStringsSet) HasAny(_ []string) bool {
-	return true
-}
-
-func AllStrings() *allStringsSet {
-	return &allStringsSet{}
-}
-
-func (e allStringsSet) Has(_ string) bool {
-	return true
-}
-
-func (e allStringsSet) Count() int {
-	return -1
-}