diff --git a/storage/local/codec/codec.go b/storage/local/codable/codable.go
similarity index 65%
rename from storage/local/codec/codec.go
rename to storage/local/codable/codable.go
index c75b7a1401..27f9a979c8 100644
--- a/storage/local/codec/codec.go
+++ b/storage/local/codable/codable.go
@@ -11,7 +11,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// Package codec provides types that implement encoding.BinaryMarshaler and
+// Package codable provides types that implement encoding.BinaryMarshaler and
 // encoding.BinaryUnmarshaler and functions that help to encode and decode
 // primitives. The Prometheus storage backend uses them to persist objects to
 // files and to save objects in LevelDB.
@@ -28,11 +28,10 @@
 //
 // Maps are encoded as the number of mappings as a varint, followed by the
 // mappings, each of which consists of the key followed by the value.
-package codec
+package codable
 
 import (
 	"bytes"
-	"encoding"
 	"encoding/binary"
 	"fmt"
 	"io"
@@ -43,14 +42,6 @@ import (
 	"github.com/prometheus/prometheus/storage/metric"
 )
 
-// codable implements both, encoding.BinaryMarshaler and
-// encoding.BinaryUnmarshaler, which is only needed internally and therefore not
-// exported for now.
-type codable interface {
-	encoding.BinaryMarshaler
-	encoding.BinaryUnmarshaler
-}
-
 // A byteReader is an io.ByteReader that also implements the vanilla io.Reader
 // interface.
 type byteReader interface {
@@ -145,12 +136,12 @@ func decodeString(b byteReader) (string, error) {
 	return string(buf), nil
 }
 
-// A CodableMetric is a clientmodel.Metric that implements
+// A Metric is a clientmodel.Metric that implements
 // encoding.BinaryMarshaler and encoding.BinaryUnmarshaler.
-type CodableMetric clientmodel.Metric
+type Metric clientmodel.Metric
 
 // MarshalBinary implements encoding.BinaryMarshaler.
-func (m CodableMetric) MarshalBinary() ([]byte, error) {
+func (m Metric) MarshalBinary() ([]byte, error) {
 	buf := &bytes.Buffer{}
 	if err := EncodeVarint(buf, int64(len(m))); err != nil {
 		return nil, err
@@ -167,20 +158,20 @@ func (m CodableMetric) MarshalBinary() ([]byte, error) {
 }
 
 // UnmarshalBinary implements encoding.BinaryUnmarshaler. It can be used with the
-// zero value of CodableMetric.
-func (m *CodableMetric) UnmarshalBinary(buf []byte) error {
+// zero value of Metric.
+func (m *Metric) UnmarshalBinary(buf []byte) error {
 	return m.UnmarshalFromReader(bytes.NewReader(buf))
 }
 
-// UnmarshalFromReader unmarshals a CodableMetric from a reader that implements
+// UnmarshalFromReader unmarshals a Metric from a reader that implements
 // both, io.Reader and io.ByteReader. It can be used with the zero value of
-// CodableMetric.
-func (m *CodableMetric) UnmarshalFromReader(r byteReader) error {
+// Metric.
+func (m *Metric) UnmarshalFromReader(r byteReader) error {
 	numLabelPairs, err := binary.ReadVarint(r)
 	if err != nil {
 		return err
 	}
-	*m = make(CodableMetric, numLabelPairs)
+	*m = make(Metric, numLabelPairs)
 
 	for ; numLabelPairs > 0; numLabelPairs-- {
 		ln, err := decodeString(r)
@@ -196,31 +187,64 @@ func (m *CodableMetric) UnmarshalFromReader(r byteReader) error {
 	return nil
 }
 
-// A CodableFingerprint is a clientmodel.Fingerprint that implements
+// A Fingerprint is a clientmodel.Fingerprint that implements
 // encoding.BinaryMarshaler and encoding.BinaryUnmarshaler. The implementation
 // depends on clientmodel.Fingerprint to be convertible to uint64. It encodes
 // the fingerprint as a big-endian uint64.
-type CodableFingerprint clientmodel.Fingerprint
+type Fingerprint clientmodel.Fingerprint
 
 // MarshalBinary implements encoding.BinaryMarshaler.
-func (fp CodableFingerprint) MarshalBinary() ([]byte, error) {
+func (fp Fingerprint) MarshalBinary() ([]byte, error) {
 	b := make([]byte, 8)
 	binary.BigEndian.PutUint64(b, uint64(fp))
 	return b, nil
 }
 
 // UnmarshalBinary implements encoding.BinaryUnmarshaler.
-func (fp *CodableFingerprint) UnmarshalBinary(buf []byte) error {
-	*fp = CodableFingerprint(binary.BigEndian.Uint64(buf))
+func (fp *Fingerprint) UnmarshalBinary(buf []byte) error {
+	*fp = Fingerprint(binary.BigEndian.Uint64(buf))
 	return nil
 }
 
-// CodableFingerprints is a clientmodel.Fingerprints that implements
-// encoding.BinaryMarshaler and encoding.BinaryUnmarshaler.
-type CodableFingerprints clientmodel.Fingerprints
+// FingerprintSet is a map[clientmodel.Fingerprint]struct{} that
+// implements encoding.BinaryMarshaler and encoding.BinaryUnmarshaler. Its
+// binary form is identical to that of Fingerprints.
+type FingerprintSet map[clientmodel.Fingerprint]struct{}
 
 // MarshalBinary implements encoding.BinaryMarshaler.
-func (fps CodableFingerprints) MarshalBinary() ([]byte, error) {
+func (fps FingerprintSet) MarshalBinary() ([]byte, error) {
+	b := make([]byte, binary.MaxVarintLen64+len(fps)*8)
+	lenBytes := binary.PutVarint(b, int64(len(fps)))
+	offset := lenBytes
+
+	for fp := range fps {
+		binary.BigEndian.PutUint64(b[offset:], uint64(fp))
+		offset += 8
+	}
+	return b[:len(fps)*8+lenBytes], nil
+}
+
+// UnmarshalBinary implements encoding.BinaryUnmarshaler.
+func (fps *FingerprintSet) UnmarshalBinary(buf []byte) error {
+	numFPs, offset := binary.Varint(buf)
+	if offset <= 0 {
+		return fmt.Errorf("could not decode length of Fingerprints, varint decoding returned %d", offset)
+	}
+	*fps = make(FingerprintSet, numFPs)
+
+	for i := 0; i < int(numFPs); i++ {
+		(*fps)[clientmodel.Fingerprint(binary.BigEndian.Uint64(buf[offset+i*8:]))] = struct{}{}
+	}
+	return nil
+}
+
+// Fingerprints is a clientmodel.Fingerprints that implements
+// encoding.BinaryMarshaler and encoding.BinaryUnmarshaler. Its binary form is
+// identical to that of FingerprintSet.
+type Fingerprints clientmodel.Fingerprints
+
+// MarshalBinary implements encoding.BinaryMarshaler.
+func (fps Fingerprints) MarshalBinary() ([]byte, error) {
 	b := make([]byte, binary.MaxVarintLen64+len(fps)*8)
 	lenBytes := binary.PutVarint(b, int64(len(fps)))
 
@@ -231,12 +255,12 @@ func (fps CodableFingerprints) MarshalBinary() ([]byte, error) {
 }
 
 // UnmarshalBinary implements encoding.BinaryUnmarshaler.
-func (fps *CodableFingerprints) UnmarshalBinary(buf []byte) error {
+func (fps *Fingerprints) UnmarshalBinary(buf []byte) error {
 	numFPs, offset := binary.Varint(buf)
 	if offset <= 0 {
-		return fmt.Errorf("could not decode length of CodableFingerprints, varint decoding returned %d", offset)
+		return fmt.Errorf("could not decode length of Fingerprints, varint decoding returned %d", offset)
 	}
-	*fps = make(CodableFingerprints, numFPs)
+	*fps = make(Fingerprints, numFPs)
 
 	for i := range *fps {
 		(*fps)[i] = clientmodel.Fingerprint(binary.BigEndian.Uint64(buf[offset+i*8:]))
@@ -244,12 +268,12 @@ func (fps *CodableFingerprints) UnmarshalBinary(buf []byte) error {
 	return nil
 }
 
-// CodableLabelPair is a metric.LabelPair that implements
+// LabelPair is a metric.LabelPair that implements
 // encoding.BinaryMarshaler and encoding.BinaryUnmarshaler.
-type CodableLabelPair metric.LabelPair
+type LabelPair metric.LabelPair
 
 // MarshalBinary implements encoding.BinaryMarshaler.
-func (lp CodableLabelPair) MarshalBinary() ([]byte, error) {
+func (lp LabelPair) MarshalBinary() ([]byte, error) {
 	buf := &bytes.Buffer{}
 	if err := encodeString(buf, string(lp.Name)); err != nil {
 		return nil, err
@@ -261,7 +285,7 @@ func (lp CodableLabelPair) MarshalBinary() ([]byte, error) {
 }
 
 // UnmarshalBinary implements encoding.BinaryUnmarshaler.
-func (lp *CodableLabelPair) UnmarshalBinary(buf []byte) error {
+func (lp *LabelPair) UnmarshalBinary(buf []byte) error {
 	r := bytes.NewReader(buf)
 	n, err := decodeString(r)
 	if err != nil {
@@ -276,12 +300,12 @@ func (lp *CodableLabelPair) UnmarshalBinary(buf []byte) error {
 	return nil
 }
 
-// CodableLabelName is a clientmodel.LabelName that implements
+// LabelName is a clientmodel.LabelName that implements
 // encoding.BinaryMarshaler and encoding.BinaryUnmarshaler.
-type CodableLabelName clientmodel.LabelName
+type LabelName clientmodel.LabelName
 
 // MarshalBinary implements encoding.BinaryMarshaler.
-func (l CodableLabelName) MarshalBinary() ([]byte, error) {
+func (l LabelName) MarshalBinary() ([]byte, error) {
 	buf := &bytes.Buffer{}
 	if err := encodeString(buf, string(l)); err != nil {
 		return nil, err
@@ -290,22 +314,61 @@ func (l CodableLabelName) MarshalBinary() ([]byte, error) {
 }
 
 // UnmarshalBinary implements encoding.BinaryUnmarshaler.
-func (l *CodableLabelName) UnmarshalBinary(buf []byte) error {
+func (l *LabelName) UnmarshalBinary(buf []byte) error {
 	r := bytes.NewReader(buf)
 	n, err := decodeString(r)
 	if err != nil {
 		return err
 	}
-	*l = CodableLabelName(n)
+	*l = LabelName(n)
 	return nil
 }
 
-// CodableLabelValues is a clientmodel.LabelValues that implements
-// encoding.BinaryMarshaler and encoding.BinaryUnmarshaler.
-type CodableLabelValues clientmodel.LabelValues
+// LabelValueSet is a map[clientmodel.LabelValue]struct{} that implements
+// encoding.BinaryMarshaler and encoding.BinaryUnmarshaler. Its binary form is
+// identical to that of LabelValues.
+type LabelValueSet map[clientmodel.LabelValue]struct{}
 
 // MarshalBinary implements encoding.BinaryMarshaler.
-func (vs CodableLabelValues) MarshalBinary() ([]byte, error) {
+func (vs LabelValueSet) MarshalBinary() ([]byte, error) {
+	buf := &bytes.Buffer{}
+	if err := EncodeVarint(buf, int64(len(vs))); err != nil {
+		return nil, err
+	}
+	for v := range vs {
+		if err := encodeString(buf, string(v)); err != nil {
+			return nil, err
+		}
+	}
+	return buf.Bytes(), nil
+}
+
+// UnmarshalBinary implements encoding.BinaryUnmarshaler.
+func (vs *LabelValueSet) UnmarshalBinary(buf []byte) error {
+	r := bytes.NewReader(buf)
+	numValues, err := binary.ReadVarint(r)
+	if err != nil {
+		return err
+	}
+	*vs = make(LabelValueSet, numValues)
+
+	for i := int64(0); i < numValues; i++ {
+		v, err := decodeString(r)
+		if err != nil {
+			return err
+		}
+		(*vs)[clientmodel.LabelValue(v)] = struct{}{}
+	}
+	return nil
+}
+
+// LabelValues is a clientmodel.LabelValues that implements
+// encoding.BinaryMarshaler and encoding.BinaryUnmarshaler. Its binary form is
+// identical to that of LabelValueSet.
+type LabelValues clientmodel.LabelValues
+
+// MarshalBinary implements encoding.BinaryMarshaler.
+func (vs LabelValues) MarshalBinary() ([]byte, error) {
 	buf := &bytes.Buffer{}
 	if err := EncodeVarint(buf, int64(len(vs))); err != nil {
 		return nil, err
@@ -319,13 +382,13 @@ func (vs CodableLabelValues) MarshalBinary() ([]byte, error) {
 }
 
 // UnmarshalBinary implements encoding.BinaryUnmarshaler.
-func (vs *CodableLabelValues) UnmarshalBinary(buf []byte) error {
+func (vs *LabelValues) UnmarshalBinary(buf []byte) error {
 	r := bytes.NewReader(buf)
 	numValues, err := binary.ReadVarint(r)
 	if err != nil {
 		return err
 	}
-	*vs = make(CodableLabelValues, numValues)
+	*vs = make(LabelValues, numValues)
 
 	for i := range *vs {
 		v, err := decodeString(r)
@@ -337,14 +400,14 @@ func (vs *CodableLabelValues) UnmarshalBinary(buf []byte) error {
 	return nil
 }
 
-// CodableTimeRange is used to define a time range and implements
+// TimeRange is used to define a time range and implements
 // encoding.BinaryMarshaler and encoding.BinaryUnmarshaler.
-type CodableTimeRange struct {
+type TimeRange struct {
 	First, Last clientmodel.Timestamp
 }
 
 // MarshalBinary implements encoding.BinaryMarshaler.
-func (tr CodableTimeRange) MarshalBinary() ([]byte, error) {
+func (tr TimeRange) MarshalBinary() ([]byte, error) {
 	buf := &bytes.Buffer{}
 	if err := EncodeVarint(buf, int64(tr.First)); err != nil {
 		return nil, err
@@ -356,7 +419,7 @@ func (tr CodableTimeRange) MarshalBinary() ([]byte, error) {
 }
 
 // UnmarshalBinary implements encoding.BinaryUnmarshaler.
-func (tr *CodableTimeRange) UnmarshalBinary(buf []byte) error {
+func (tr *TimeRange) UnmarshalBinary(buf []byte) error {
 	r := bytes.NewReader(buf)
 	first, err := binary.ReadVarint(r)
 	if err != nil {
diff --git a/storage/local/codable/codable_test.go b/storage/local/codable/codable_test.go
new file mode 100644
index 0000000000..710cbf9be8
--- /dev/null
+++ b/storage/local/codable/codable_test.go
@@ -0,0 +1,149 @@
+// Copyright 2014 Prometheus Team
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package codable
+
+import (
+	"encoding"
+	"reflect"
+	"testing"
+)
+
+func newFingerprint(fp int64) *Fingerprint {
+	cfp := Fingerprint(fp)
+	return &cfp
+}
+
+func newLabelName(ln string) *LabelName {
+	cln := LabelName(ln)
+	return &cln
+}
+
+func TestCodec(t *testing.T) {
+	scenarios := []struct {
+		in    encoding.BinaryMarshaler
+		out   encoding.BinaryUnmarshaler
+		equal func(in, out interface{}) bool
+	}{
+		{
+			in: &Metric{
+				"label_1": "value_2",
+				"label_2": "value_2",
+				"label_3": "value_3",
+			},
+			out: &Metric{},
+		}, {
+			in:  newFingerprint(12345),
+			out: newFingerprint(0),
+		}, {
+			in:  &Fingerprints{1, 2, 56, 1234},
+			out: &Fingerprints{},
+		}, {
+			in:  &Fingerprints{1, 2, 56, 1234},
+			out: &FingerprintSet{},
+			equal: func(in, out interface{}) bool {
+				inSet := FingerprintSet{}
+				for _, fp := range *(in.(*Fingerprints)) {
+					inSet[fp] = struct{}{}
+				}
+				return reflect.DeepEqual(inSet, *(out.(*FingerprintSet)))
+			},
+		}, {
+			in: &FingerprintSet{
+				1:    struct{}{},
+				2:    struct{}{},
+				56:   struct{}{},
+				1234: struct{}{},
+			},
+			out: &FingerprintSet{},
+		}, {
+			in: &FingerprintSet{
+				1:    struct{}{},
+				2:    struct{}{},
+				56:   struct{}{},
+				1234: struct{}{},
+			},
+			out: &Fingerprints{},
+			equal: func(in, out interface{}) bool {
+				outSet := FingerprintSet{}
+				for _, fp := range *(out.(*Fingerprints)) {
+					outSet[fp] = struct{}{}
+				}
+				return reflect.DeepEqual(outSet, *(in.(*FingerprintSet)))
+			},
+		}, {
+			in: &LabelPair{
+				Name:  "label_name",
+				Value: "label_value",
+			},
+			out: &LabelPair{},
+		}, {
+			in:  newLabelName("label_name"),
+			out: newLabelName(""),
+		}, {
+			in:  &LabelValues{"value_1", "value_2", "value_3"},
+			out: &LabelValues{},
+		}, {
+			in:  &LabelValues{"value_1", "value_2", "value_3"},
+			out: &LabelValueSet{},
+			equal: func(in, out interface{}) bool {
+				inSet := LabelValueSet{}
+				for _, lv := range *(in.(*LabelValues)) {
+					inSet[lv] = struct{}{}
+				}
+				return reflect.DeepEqual(inSet, *(out.(*LabelValueSet)))
+			},
+		}, {
+			in: &LabelValueSet{
+				"value_1": struct{}{},
+				"value_2": struct{}{},
+				"value_3": struct{}{},
+			},
+			out: &LabelValueSet{},
+		}, {
+			in: &LabelValueSet{
+				"value_1": struct{}{},
+				"value_2": struct{}{},
+				"value_3": struct{}{},
+			},
+			out: &LabelValues{},
+			equal: func(in, out interface{}) bool {
+				outSet := LabelValueSet{}
+				for _, lv := range *(out.(*LabelValues)) {
+					outSet[lv] = struct{}{}
+				}
+				return reflect.DeepEqual(outSet, *(in.(*LabelValueSet)))
+			},
+		}, {
+			in:  &TimeRange{42, 2001},
+			out: &TimeRange{},
+		},
+	}
+
+	for i, s := range scenarios {
+		encoded, err := s.in.MarshalBinary()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if err := s.out.UnmarshalBinary(encoded); err != nil {
+			t.Fatal(err)
+		}
+		equal := s.equal
+		if equal == nil {
+			equal = reflect.DeepEqual
+		}
+		if !equal(s.in, s.out) {
+			t.Errorf("%d. Got: %v; want %v; encoded bytes are: %v", i, s.out, s.in, encoded)
+		}
+	}
+}
diff --git a/storage/local/codec/codec_test.go b/storage/local/codec/codec_test.go
deleted file mode 100644
index 43c27f8800..0000000000
--- a/storage/local/codec/codec_test.go
+++ /dev/null
@@ -1,130 +0,0 @@
-// Copyright 2014 Prometheus Team
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package codec
-
-import (
-	"testing"
-
-	clientmodel "github.com/prometheus/client_golang/model"
-)
-
-func newCodableFingerprint(fp int64) *CodableFingerprint {
-	cfp := CodableFingerprint(fp)
-	return &cfp
-}
-
-func newCodableLabelName(ln string) *CodableLabelName {
-	cln := CodableLabelName(ln)
-	return &cln
-}
-
-func TestCodec(t *testing.T) {
-	scenarios := []struct {
-		in    codable
-		out   codable
-		equal func(in, out codable) bool
-	}{
-		{
-			in: &CodableMetric{
-				"label_1": "value_2",
-				"label_2": "value_2",
-				"label_3": "value_3",
-			},
-			out: &CodableMetric{},
-			equal: func(in, out codable) bool {
-				m1 := (*clientmodel.Metric)(in.(*CodableMetric))
-				m2 := (*clientmodel.Metric)(out.(*CodableMetric))
-				return m1.Equal(*m2)
-			},
-		}, {
-			in:  newCodableFingerprint(12345),
-			out: newCodableFingerprint(0),
-			equal: func(in, out codable) bool {
-				return *in.(*CodableFingerprint) == *out.(*CodableFingerprint)
-			},
-		}, {
-			in:  &CodableFingerprints{1, 2, 56, 1234},
-			out: &CodableFingerprints{},
-			equal: func(in, out codable) bool {
-				fps1 := *in.(*CodableFingerprints)
-				fps2 := *out.(*CodableFingerprints)
-				if len(fps1) != len(fps2) {
-					return false
-				}
-				for i := range fps1 {
-					if fps1[i] != fps2[i] {
-						return false
-					}
-				}
-				return true
-			},
-		}, {
-			in: &CodableLabelPair{
-				Name:  "label_name",
-				Value: "label_value",
-			},
-			out: &CodableLabelPair{},
-			equal: func(in, out codable) bool {
-				lp1 := *in.(*CodableLabelPair)
-				lp2 := *out.(*CodableLabelPair)
-				return lp1 == lp2
-			},
-		}, {
-			in:  newCodableLabelName("label_name"),
-			out: newCodableLabelName(""),
-			equal: func(in, out codable) bool {
-				ln1 := *in.(*CodableLabelName)
-				ln2 := *out.(*CodableLabelName)
-				return ln1 == ln2
-			},
-		}, {
-			in:  &CodableLabelValues{"value_1", "value_2", "value_3"},
-			out: &CodableLabelValues{},
-			equal: func(in, out codable) bool {
-				lvs1 := *in.(*CodableLabelValues)
-				lvs2 := *out.(*CodableLabelValues)
-				if len(lvs1) != len(lvs2) {
-					return false
-				}
-				for i := range lvs1 {
-					if lvs1[i] != lvs2[i] {
-						return false
-					}
-				}
-				return true
-			},
-		}, {
-			in:  &CodableTimeRange{42, 2001},
-			out: &CodableTimeRange{},
-			equal: func(in, out codable) bool {
-				ln1 := *in.(*CodableTimeRange)
-				ln2 := *out.(*CodableTimeRange)
-				return ln1 == ln2
-			},
-		},
-	}
-
-	for i, s := range scenarios {
-		encoded, err := s.in.MarshalBinary()
-		if err != nil {
-			t.Fatal(err)
-		}
-		if err := s.out.UnmarshalBinary(encoded); err != nil {
-			t.Fatal(err)
-		}
-		if !s.equal(s.in, s.out) {
-			t.Errorf("%d. Got: %v; want %v; encoded bytes are: %v", i, s.out, s.in, encoded)
-		}
-	}
-}
diff --git a/storage/local/index/index.go b/storage/local/index/index.go
index 7a3de7093f..fe272fbe70 100644
--- a/storage/local/index/index.go
+++ b/storage/local/index/index.go
@@ -22,9 +22,8 @@ import (
 
 	clientmodel "github.com/prometheus/client_golang/model"
 
-	"github.com/prometheus/prometheus/storage/local/codec"
+	"github.com/prometheus/prometheus/storage/local/codable"
 	"github.com/prometheus/prometheus/storage/metric"
-	"github.com/prometheus/prometheus/utility"
 )
 
 const (
@@ -58,7 +57,7 @@ func (i *FingerprintMetricIndex) IndexBatch(mapping FingerprintMetricMapping) er
 	b := i.NewBatch()
 
 	for fp, m := range mapping {
-		b.Put(codec.CodableFingerprint(fp), codec.CodableMetric(m))
+		b.Put(codable.Fingerprint(fp), codable.Metric(m))
 	}
 
 	return i.Commit(b)
@@ -73,7 +72,7 @@ func (i *FingerprintMetricIndex) UnindexBatch(mapping FingerprintMetricMapping)
 	b := i.NewBatch()
 
 	for fp := range mapping {
-		b.Delete(codec.CodableFingerprint(fp))
+		b.Delete(codable.Fingerprint(fp))
 	}
 
 	return i.Commit(b)
@@ -84,7 +83,7 @@ func (i *FingerprintMetricIndex) UnindexBatch(mapping FingerprintMetricMapping)
 //
 // This method is goroutine-safe.
 func (i *FingerprintMetricIndex) Lookup(fp clientmodel.Fingerprint) (metric clientmodel.Metric, ok bool, err error) {
-	ok, err = i.Get(codec.CodableFingerprint(fp), (*codec.CodableMetric)(&metric))
+	ok, err = i.Get(codable.Fingerprint(fp), (*codable.Metric)(&metric))
 	return
 }
 
@@ -105,7 +104,7 @@ func NewFingerprintMetricIndex(basePath string) (*FingerprintMetricIndex, error)
 
 // LabelNameLabelValuesMapping is an in-memory map of label names to
 // label values.
-type LabelNameLabelValuesMapping map[clientmodel.LabelName]clientmodel.LabelValues
+type LabelNameLabelValuesMapping map[clientmodel.LabelName]codable.LabelValueSet
 
 // LabelNameLabelValuesIndex is a KeyValueStore that maps existing label names
 // to all label values stored for that label name.
@@ -118,19 +117,17 @@ type LabelNameLabelValuesIndex struct {
 // a deletion of that mapping from the index.
 //
 // While this method is fundamentally goroutine-safe, note that the order of
-// execution for multiple batches executed concurrently is undefined. Also, it
-// is in general not safe to mutate the index while Extend or Reduce are
-// running.
+// execution for multiple batches executed concurrently is undefined.
 func (i *LabelNameLabelValuesIndex) IndexBatch(b LabelNameLabelValuesMapping) error {
 	batch := i.NewBatch()
 
 	for name, values := range b {
 		if len(values) == 0 {
-			if err := batch.Delete(codec.CodableLabelName(name)); err != nil {
+			if err := batch.Delete(codable.LabelName(name)); err != nil {
 				return err
 			}
 		} else {
-			if err := batch.Put(codec.CodableLabelName(name), codec.CodableLabelValues(values)); err != nil {
+			if err := batch.Put(codable.LabelName(name), values); err != nil {
 				return err
 			}
 		}
@@ -145,80 +142,21 @@ func (i *LabelNameLabelValuesIndex) IndexBatch(b LabelNameLabelValuesMapping) er
 //
 // This method is goroutine-safe.
 func (i *LabelNameLabelValuesIndex) Lookup(l clientmodel.LabelName) (values clientmodel.LabelValues, ok bool, err error) {
-	ok, err = i.Get(codec.CodableLabelName(l), (*codec.CodableLabelValues)(&values))
+	ok, err = i.Get(codable.LabelName(l), (*codable.LabelValues)(&values))
 	return
 }
 
-// Extend incorporates the given metric into the index, i.e. it creates new
-// label name to label values mappings for new label names, and it extends the
-// label values list mapped from already existing label names appropriately.
+// LookupSet looks up all label values for a given label name. Looking up a
+// non-existing label name is not an error. In that case, (nil, false, nil) is
+// returned.
 //
-// This method is not goroutine-safe.
-func (i *LabelNameLabelValuesIndex) Extend(m clientmodel.Metric) error {
-	b := make(LabelNameLabelValuesMapping, len(m))
-	for ln, lv := range m {
-		baseLVs, _, err := i.Lookup(ln)
-		if err != nil {
-			return err
-		}
-		lvSet := utility.Set{}
-		for _, baseLV := range baseLVs {
-			lvSet.Add(baseLV)
-		}
-		lvSet.Add(lv)
-		if len(lvSet) == len(baseLVs) {
-			continue
-		}
-		lvs := make(clientmodel.LabelValues, 0, len(lvSet))
-		for v := range lvSet {
-			lvs = append(lvs, v.(clientmodel.LabelValue))
-		}
-		b[ln] = lvs
+// This method is goroutine-safe.
+func (i *LabelNameLabelValuesIndex) LookupSet(l clientmodel.LabelName) (values map[clientmodel.LabelValue]struct{}, ok bool, err error) {
+	ok, err = i.Get(codable.LabelName(l), (*codable.LabelValueSet)(&values))
+	if values == nil {
+		values = map[clientmodel.LabelValue]struct{}{}
 	}
-	return i.IndexBatch(b)
-}
-
-// Reduce removes label values from the index based on the given label pair to
-// fingerprints mapping. The mapping to be passed in here is returned by
-// LabelPairFingerprintIndex.Reduce. It contains all the label pairs that have
-// now fewer fingerprints mapped to it. This method checks if any label pair has
-// arrived at zero mapped fingerprints. In that case, the value of that label
-// pair is removed from the list of label values mapped to the name of that
-// label pair. Label names that are then mapped to zero label values are removed
-// entirely from the index.
-//
-// This method is not goroutine-safe.
-func (i *LabelNameLabelValuesIndex) Reduce(m LabelPairFingerprintsMapping) error {
-	b := make(LabelNameLabelValuesMapping, len(m))
-	for lp, fps := range m {
-		if len(fps) != 0 {
-			continue
-		}
-		ln := lp.Name
-		lv := lp.Value
-		baseValues, ok := b[ln]
-		if !ok {
-			var err error
-			baseValues, _, err = i.Lookup(ln)
-			if err != nil {
-				return err
-			}
-		}
-		lvSet := utility.Set{}
-		for _, baseValue := range baseValues {
-			lvSet.Add(baseValue)
-		}
-		lvSet.Remove(lv)
-		if len(lvSet) == len(baseValues) {
-			continue
-		}
-		lvs := make(clientmodel.LabelValues, 0, len(lvSet))
-		for v := range lvSet {
-			lvs = append(lvs, v.(clientmodel.LabelValue))
-		}
-		b[ln] = lvs
-	}
-	return i.IndexBatch(b)
+	return
 }
 
 // NewLabelNameLabelValuesIndex returns a LevelDB-backed
@@ -238,7 +176,7 @@ func NewLabelNameLabelValuesIndex(basePath string) (*LabelNameLabelValuesIndex,
 
 // LabelPairFingerprintsMapping is an in-memory map of label pairs to
 // fingerprints.
-type LabelPairFingerprintsMapping map[metric.LabelPair]clientmodel.Fingerprints
+type LabelPairFingerprintsMapping map[metric.LabelPair]codable.FingerprintSet
 
 // LabelPairFingerprintIndex is a KeyValueStore that maps existing label pairs
 // to the fingerprints of all metrics containing those label pairs.
@@ -251,17 +189,15 @@ type LabelPairFingerprintIndex struct {
 // from the index.
 //
 // While this method is fundamentally goroutine-safe, note that the order of
-// execution for multiple batches executed concurrently is undefined. Also, it
-// is in general not safe to mutate the index while Extend or Reduce are
-// running.
+// execution for multiple batches executed concurrently is undefined.
 func (i *LabelPairFingerprintIndex) IndexBatch(m LabelPairFingerprintsMapping) error {
 	batch := i.NewBatch()
 
 	for pair, fps := range m {
 		if len(fps) == 0 {
-			batch.Delete(codec.CodableLabelPair(pair))
+			batch.Delete(codable.LabelPair(pair))
 		} else {
-			batch.Put(codec.CodableLabelPair(pair), codec.CodableFingerprints(fps))
+			batch.Put(codable.LabelPair(pair), fps)
 		}
 	}
 
@@ -274,70 +210,21 @@ func (i *LabelPairFingerprintIndex) IndexBatch(m LabelPairFingerprintsMapping) e
 //
 // This method is goroutine-safe.
 func (i *LabelPairFingerprintIndex) Lookup(p metric.LabelPair) (fps clientmodel.Fingerprints, ok bool, err error) {
-	ok, err = i.Get((codec.CodableLabelPair)(p), (*codec.CodableFingerprints)(&fps))
+	ok, err = i.Get((codable.LabelPair)(p), (*codable.Fingerprints)(&fps))
 	return
 }
 
-// Extend incorporates the given metric into the index, i.e. it creates new
-// label pair to fingerprint mappings for new label pairs, and it extends the
-// fingerprint list mapped from already existing label pairs appropriately.
+// LookupSet looks up all fingerprints for a given label pair.  Looking up a
+// non-existing label pair is not an error. In that case, (nil, false, nil) is
+// returned.
 //
-// This method is not goroutine-safe.
-func (i *LabelPairFingerprintIndex) Extend(m clientmodel.Metric, fp clientmodel.Fingerprint) error {
-	b := make(LabelPairFingerprintsMapping, len(m))
-	for ln, lv := range m {
-		lp := metric.LabelPair{Name: ln, Value: lv}
-		baseFPs, _, err := i.Lookup(lp)
-		if err != nil {
-			return err
-		}
-		fpSet := utility.Set{}
-		for _, baseFP := range baseFPs {
-			fpSet.Add(baseFP)
-		}
-		fpSet.Add(fp)
-		if len(fpSet) == len(baseFPs) {
-			continue
-		}
-		fps := make(clientmodel.Fingerprints, 0, len(fpSet))
-		for f := range fpSet {
-			fps = append(fps, f.(clientmodel.Fingerprint))
-		}
-		b[lp] = fps
-
+// This method is goroutine-safe.
+func (i *LabelPairFingerprintIndex) LookupSet(p metric.LabelPair) (fps map[clientmodel.Fingerprint]struct{}, ok bool, err error) {
+	ok, err = i.Get((codable.LabelPair)(p), (*codable.FingerprintSet)(&fps))
+	if fps == nil {
+		fps = map[clientmodel.Fingerprint]struct{}{}
 	}
-	return i.IndexBatch(b)
-}
-
-// Reduce removes the given fingerprint from the fingerprint lists mapped from
-// the label pairs contained in the given metric. All the updated mappings are
-// returned (for consumption by LabelNameLabelValuesIndex.Reduce).
-//
-// This method is not goroutine-safe.
-func (i *LabelPairFingerprintIndex) Reduce(m clientmodel.Metric, fp clientmodel.Fingerprint) (LabelPairFingerprintsMapping, error) {
-	b := make(LabelPairFingerprintsMapping, len(m))
-	for ln, lv := range m {
-		lp := metric.LabelPair{Name: ln, Value: lv}
-		baseFPs, _, err := i.Lookup(lp)
-		if err != nil {
-			return nil, err
-		}
-		fpSet := utility.Set{}
-		for _, baseFP := range baseFPs {
-			fpSet.Add(baseFP)
-		}
-		fpSet.Remove(fp)
-		if len(fpSet) == len(baseFPs) {
-			continue
-		}
-		fps := make(clientmodel.Fingerprints, 0, len(fpSet))
-		for f := range fpSet {
-			fps = append(fps, f.(clientmodel.Fingerprint))
-		}
-		b[lp] = fps
-
-	}
-	return b, i.IndexBatch(b)
+	return
 }
 
 // NewLabelPairFingerprintIndex returns a LevelDB-backed
@@ -367,8 +254,8 @@ type FingerprintTimeRangeIndex struct {
 //
 // This method is goroutine-safe.
 func (i *FingerprintTimeRangeIndex) Lookup(fp clientmodel.Fingerprint) (firstTime, lastTime clientmodel.Timestamp, ok bool, err error) {
-	var tr codec.CodableTimeRange
-	ok, err = i.Get(codec.CodableFingerprint(fp), &tr)
+	var tr codable.TimeRange
+	ok, err = i.Get(codable.Fingerprint(fp), &tr)
 	return tr.First, tr.Last, ok, err
 }
 
@@ -376,7 +263,7 @@ func (i *FingerprintTimeRangeIndex) Lookup(fp clientmodel.Fingerprint) (firstTim
 //
 // This method is goroutine-safe.
 func (i *FingerprintTimeRangeIndex) Has(fp clientmodel.Fingerprint) (ok bool, err error) {
-	return i.KeyValueStore.Has(codec.CodableFingerprint(fp))
+	return i.KeyValueStore.Has(codable.Fingerprint(fp))
 }
 
 // NewFingerprintTimeRangeIndex returns a LevelDB-backed
diff --git a/storage/local/interface.go b/storage/local/interface.go
index cb32bd16e9..b4e216b1ce 100644
--- a/storage/local/interface.go
+++ b/storage/local/interface.go
@@ -90,20 +90,20 @@ type Persistence interface {
 	// GetLabelValuesForLabelName returns the label values for the given
 	// label name.
 	GetLabelValuesForLabelName(clientmodel.LabelName) (clientmodel.LabelValues, error)
-	// GetFingerprintsModifiedBefore returns the fingerprints whose timeseries
-	// have live samples before the provided timestamp.
-	GetFingerprintsModifiedBefore(clientmodel.Timestamp) ([]clientmodel.Fingerprint, error)
 
-	// IndexMetric indexes the given metric for the needs of
-	// GetFingerprintsForLabelPair and GetLabelValuesForLabelName.
-	IndexMetric(clientmodel.Metric, clientmodel.Fingerprint) error
-	// UnindexMetric removes references to the given metric from the indexes
-	// used for GetFingerprintsForLabelPair and
+	// IndexMetric queues the given metric for addition to the indexes
+	// needed by GetFingerprintsForLabelPair and GetLabelValuesForLabelName.
+	// If the queue is full, this method blocks until the metric can be queued.
+	// This method is goroutine-safe.
+	IndexMetric(clientmodel.Metric, clientmodel.Fingerprint)
+	// UnindexMetric queues references to the given metric for removal from
+	// the indexes used for GetFingerprintsForLabelPair and
 	// GetLabelValuesForLabelName. The index of fingerprints to archived
-	// metrics is not affected by this method. (In fact, never call this
+	// metrics is not affected by this removal. (In fact, never call this
 	// method for an archived metric. To drop an archived metric, call
-	// DropArchivedFingerprint.)
-	UnindexMetric(clientmodel.Metric, clientmodel.Fingerprint) error
+	// DropArchivedFingerprint.)  If the queue is full, this method blocks
+	// until the metric can be queued. This method is goroutine-safe.
+	UnindexMetric(clientmodel.Metric, clientmodel.Fingerprint)
 
 	// ArchiveMetric persists the mapping of the given fingerprint to the
 	// given metric, together with the first and last timestamp of the
@@ -118,12 +118,15 @@ type Persistence interface {
 	HasArchivedMetric(clientmodel.Fingerprint) (
 		hasMetric bool, firstTime, lastTime clientmodel.Timestamp, err error,
 	)
+	// GetFingerprintsModifiedBefore returns the fingerprints of archived
+	// timeseries that have live samples before the provided timestamp.
+	GetFingerprintsModifiedBefore(clientmodel.Timestamp) ([]clientmodel.Fingerprint, error)
 	// GetArchivedMetric retrieves the archived metric with the given
 	// fingerprint.
 	GetArchivedMetric(clientmodel.Fingerprint) (clientmodel.Metric, error)
 	// DropArchivedMetric deletes an archived fingerprint and its
-	// corresponding metric entirely. It also un-indexes the metric (no need
-	// to call UnindexMetric for the deleted metric.)
+	// corresponding metric entirely. It also queues the metric for
+	// un-indexing (no need to call UnindexMetric for the deleted metric.)
 	DropArchivedMetric(clientmodel.Fingerprint) error
 	// UnarchiveMetric deletes an archived fingerprint and its metric, but
 	// (in contrast to DropArchivedMetric) does not un-index the metric.
diff --git a/storage/local/persistence.go b/storage/local/persistence.go
index 4e6ac2ce96..d105cf081b 100644
--- a/storage/local/persistence.go
+++ b/storage/local/persistence.go
@@ -20,12 +20,13 @@ import (
 	"io"
 	"os"
 	"path"
+	"time"
 
 	"github.com/golang/glog"
 
 	clientmodel "github.com/prometheus/client_golang/model"
 
-	"github.com/prometheus/prometheus/storage/local/codec"
+	"github.com/prometheus/prometheus/storage/local/codable"
 	"github.com/prometheus/prometheus/storage/local/index"
 	"github.com/prometheus/prometheus/storage/metric"
 )
@@ -44,6 +45,10 @@ const (
 	chunkHeaderTypeOffset      = 0
 	chunkHeaderFirstTimeOffset = 1
 	chunkHeaderLastTimeOffset  = 9
+
+	indexingMaxBatchSize  = 1024
+	indexingBatchTimeout  = 500 * time.Millisecond    // Commit batch when idle for that long.
+	indexingQueueCapacity = 10 * indexingMaxBatchSize // TODO: Export as metric.
 )
 
 const (
@@ -52,6 +57,19 @@ const (
 	flagHeadChunkPersisted
 )
 
+type indexingOpType byte
+
+const (
+	add indexingOpType = iota
+	remove
+)
+
+type indexingOp struct {
+	fingerprint clientmodel.Fingerprint
+	metric      clientmodel.Metric
+	opType      indexingOpType
+}
+
 type diskPersistence struct {
 	basePath string
 	chunkLen int
@@ -60,6 +78,9 @@ type diskPersistence struct {
 	archivedFingerprintToTimeRange *index.FingerprintTimeRangeIndex
 	labelPairToFingerprints        *index.LabelPairFingerprintIndex
 	labelNameToLabelValues         *index.LabelNameLabelValuesIndex
+
+	indexingQueue   chan indexingOp
+	indexingStopped chan struct{}
 }
 
 // NewDiskPersistence returns a newly allocated Persistence backed by local disk storage, ready to use.
@@ -67,29 +88,38 @@ func NewDiskPersistence(basePath string, chunkLen int) (Persistence, error) {
 	if err := os.MkdirAll(basePath, 0700); err != nil {
 		return nil, err
 	}
-	dp := &diskPersistence{
-		basePath: basePath,
-		chunkLen: chunkLen,
-	}
 	var err error
-	dp.archivedFingerprintToMetrics, err = index.NewFingerprintMetricIndex(basePath)
+	archivedFingerprintToMetrics, err := index.NewFingerprintMetricIndex(basePath)
 	if err != nil {
 		return nil, err
 	}
-	dp.archivedFingerprintToTimeRange, err = index.NewFingerprintTimeRangeIndex(basePath)
+	archivedFingerprintToTimeRange, err := index.NewFingerprintTimeRangeIndex(basePath)
 	if err != nil {
 		return nil, err
 	}
-	dp.labelPairToFingerprints, err = index.NewLabelPairFingerprintIndex(basePath)
+	labelPairToFingerprints, err := index.NewLabelPairFingerprintIndex(basePath)
 	if err != nil {
 		return nil, err
 	}
-	dp.labelNameToLabelValues, err = index.NewLabelNameLabelValuesIndex(basePath)
+	labelNameToLabelValues, err := index.NewLabelNameLabelValuesIndex(basePath)
 	if err != nil {
 		return nil, err
 	}
 
-	return dp, nil
+	p := &diskPersistence{
+		basePath: basePath,
+		chunkLen: chunkLen,
+
+		archivedFingerprintToMetrics:   archivedFingerprintToMetrics,
+		archivedFingerprintToTimeRange: archivedFingerprintToTimeRange,
+		labelPairToFingerprints:        labelPairToFingerprints,
+		labelNameToLabelValues:         labelNameToLabelValues,
+
+		indexingQueue:   make(chan indexingOp, indexingQueueCapacity),
+		indexingStopped: make(chan struct{}),
+	}
+	go p.processIndexingQueue()
+	return p, nil
 }
 
 func (p *diskPersistence) GetFingerprintsForLabelPair(lp metric.LabelPair) (clientmodel.Fingerprints, error) {
@@ -109,8 +139,8 @@ func (p *diskPersistence) GetLabelValuesForLabelName(ln clientmodel.LabelName) (
 }
 
 func (p *diskPersistence) GetFingerprintsModifiedBefore(beforeTime clientmodel.Timestamp) ([]clientmodel.Fingerprint, error) {
-	var fp codec.CodableFingerprint
-	var tr codec.CodableTimeRange
+	var fp codable.Fingerprint
+	var tr codable.TimeRange
 	fps := []clientmodel.Fingerprint{}
 	p.archivedFingerprintToTimeRange.ForEach(func(kv index.KeyValueAccessor) error {
 		if err := kv.Value(&tr); err != nil {
@@ -257,10 +287,10 @@ func (p *diskPersistence) PersistSeriesMapAndHeads(fingerprintToSeries SeriesMap
 	if _, err := w.WriteString(headsMagicString); err != nil {
 		return err
 	}
-	if err := codec.EncodeVarint(w, headsFormatVersion); err != nil {
+	if err := codable.EncodeVarint(w, headsFormatVersion); err != nil {
 		return err
 	}
-	if err := codec.EncodeVarint(w, int64(len(fingerprintToSeries))); err != nil {
+	if err := codable.EncodeVarint(w, int64(len(fingerprintToSeries))); err != nil {
 		return err
 	}
 
@@ -275,23 +305,23 @@ func (p *diskPersistence) PersistSeriesMapAndHeads(fingerprintToSeries SeriesMap
 		if err := w.WriteByte(seriesFlags); err != nil {
 			return err
 		}
-		if err := codec.EncodeUint64(w, uint64(fp)); err != nil {
+		if err := codable.EncodeUint64(w, uint64(fp)); err != nil {
 			return err
 		}
-		buf, err := codec.CodableMetric(series.metric).MarshalBinary()
+		buf, err := codable.Metric(series.metric).MarshalBinary()
 		if err != nil {
 			return err
 		}
 		w.Write(buf)
-		if err := codec.EncodeVarint(w, int64(len(series.chunkDescs))); err != nil {
+		if err := codable.EncodeVarint(w, int64(len(series.chunkDescs))); err != nil {
 			return err
 		}
 		for i, chunkDesc := range series.chunkDescs {
 			if series.headChunkPersisted || i < len(series.chunkDescs)-1 {
-				if err := codec.EncodeVarint(w, int64(chunkDesc.firstTime())); err != nil {
+				if err := codable.EncodeVarint(w, int64(chunkDesc.firstTime())); err != nil {
 					return err
 				}
-				if err := codec.EncodeVarint(w, int64(chunkDesc.lastTime())); err != nil {
+				if err := codable.EncodeVarint(w, int64(chunkDesc.lastTime())); err != nil {
 					return err
 				}
 			} else {
@@ -345,11 +375,11 @@ func (p *diskPersistence) LoadSeriesMapAndHeads() (SeriesMap, error) {
 			return nil, err
 		}
 		headChunkPersisted := seriesFlags&flagHeadChunkPersisted != 0
-		fp, err := codec.DecodeUint64(r)
+		fp, err := codable.DecodeUint64(r)
 		if err != nil {
 			return nil, err
 		}
-		var metric codec.CodableMetric
+		var metric codable.Metric
 		if err := metric.UnmarshalFromReader(r); err != nil {
 			return nil, err
 		}
@@ -458,35 +488,24 @@ func (p *diskPersistence) DropChunks(fp clientmodel.Fingerprint, beforeTime clie
 	return false, nil
 }
 
-func (p *diskPersistence) IndexMetric(m clientmodel.Metric, fp clientmodel.Fingerprint) error {
-	// TODO: Don't do it directly, but add it to a queue (which needs to be
-	// drained before shutdown). Queuing would make this asynchronously, and
-	// then batches could be created easily.
-	if err := p.labelNameToLabelValues.Extend(m); err != nil {
-		return err
-	}
-	return p.labelPairToFingerprints.Extend(m, fp)
+// IndexMetric implements Persistence.
+func (p *diskPersistence) IndexMetric(m clientmodel.Metric, fp clientmodel.Fingerprint) {
+	p.indexingQueue <- indexingOp{fp, m, add}
 }
 
-func (p *diskPersistence) UnindexMetric(m clientmodel.Metric, fp clientmodel.Fingerprint) error {
-	// TODO: Don't do it directly, but add it to a queue (which needs to be
-	// drained before shutdown). Queuing would make this asynchronously, and
-	// then batches could be created easily.
-	labelPairs, err := p.labelPairToFingerprints.Reduce(m, fp)
-	if err != nil {
-		return err
-	}
-	return p.labelNameToLabelValues.Reduce(labelPairs)
+// UnindexMetric implements Persistence.
+func (p *diskPersistence) UnindexMetric(m clientmodel.Metric, fp clientmodel.Fingerprint) {
+	p.indexingQueue <- indexingOp{fp, m, remove}
 }
 
 func (p *diskPersistence) ArchiveMetric(
 	// TODO: Two step process, make sure this happens atomically.
 	fp clientmodel.Fingerprint, m clientmodel.Metric, first, last clientmodel.Timestamp,
 ) error {
-	if err := p.archivedFingerprintToMetrics.Put(codec.CodableFingerprint(fp), codec.CodableMetric(m)); err != nil {
+	if err := p.archivedFingerprintToMetrics.Put(codable.Fingerprint(fp), codable.Metric(m)); err != nil {
 		return err
 	}
-	if err := p.archivedFingerprintToTimeRange.Put(codec.CodableFingerprint(fp), codec.CodableTimeRange{First: first, Last: last}); err != nil {
+	if err := p.archivedFingerprintToTimeRange.Put(codable.Fingerprint(fp), codable.TimeRange{First: first, Last: last}); err != nil {
 		return err
 	}
 	return nil
@@ -510,13 +529,14 @@ func (p *diskPersistence) DropArchivedMetric(fp clientmodel.Fingerprint) error {
 	if err != nil || metric == nil {
 		return err
 	}
-	if err := p.archivedFingerprintToMetrics.Delete(codec.CodableFingerprint(fp)); err != nil {
+	if err := p.archivedFingerprintToMetrics.Delete(codable.Fingerprint(fp)); err != nil {
 		return err
 	}
-	if err := p.archivedFingerprintToTimeRange.Delete(codec.CodableFingerprint(fp)); err != nil {
+	if err := p.archivedFingerprintToTimeRange.Delete(codable.Fingerprint(fp)); err != nil {
 		return err
 	}
-	return p.UnindexMetric(metric, fp)
+	p.UnindexMetric(metric, fp)
+	return nil
 }
 
 func (p *diskPersistence) UnarchiveMetric(fp clientmodel.Fingerprint) (bool, error) {
@@ -525,16 +545,19 @@ func (p *diskPersistence) UnarchiveMetric(fp clientmodel.Fingerprint) (bool, err
 	if err != nil || !has {
 		return false, err
 	}
-	if err := p.archivedFingerprintToMetrics.Delete(codec.CodableFingerprint(fp)); err != nil {
+	if err := p.archivedFingerprintToMetrics.Delete(codable.Fingerprint(fp)); err != nil {
 		return false, err
 	}
-	if err := p.archivedFingerprintToTimeRange.Delete(codec.CodableFingerprint(fp)); err != nil {
+	if err := p.archivedFingerprintToTimeRange.Delete(codable.Fingerprint(fp)); err != nil {
 		return false, err
 	}
 	return true, nil
 }
 
 func (p *diskPersistence) Close() error {
+	close(p.indexingQueue)
+	<-p.indexingStopped
+
 	var lastError error
 	if err := p.archivedFingerprintToMetrics.Close(); err != nil {
 		lastError = err
@@ -596,6 +619,89 @@ func (p *diskPersistence) headsPath() string {
 	return path.Join(p.basePath, headsFileName)
 }
 
+func (p *diskPersistence) processIndexingQueue() {
+	batchSize := 0
+	nameToValues := index.LabelNameLabelValuesMapping{}
+	pairToFPs := index.LabelPairFingerprintsMapping{}
+	batchTimeout := time.NewTimer(indexingBatchTimeout)
+	defer batchTimeout.Stop()
+
+	commitBatch := func() {
+		if err := p.labelPairToFingerprints.IndexBatch(pairToFPs); err != nil {
+			glog.Error("Error indexing label pair to fingerprints batch: ", err)
+		}
+		if err := p.labelNameToLabelValues.IndexBatch(nameToValues); err != nil {
+			glog.Error("Error indexing label name to label values batch: ", err)
+		}
+		batchSize = 0
+		nameToValues = index.LabelNameLabelValuesMapping{}
+		pairToFPs = index.LabelPairFingerprintsMapping{}
+	}
+
+loop:
+	for {
+		select {
+		case <-batchTimeout.C:
+			if batchSize > 0 {
+				commitBatch()
+			}
+			batchTimeout.Reset(indexingBatchTimeout)
+		case op, ok := <-p.indexingQueue:
+			batchTimeout.Stop()
+
+			if !ok {
+				if batchSize > 0 {
+					commitBatch()
+				}
+				break loop
+			}
+
+			batchSize++
+			for ln, lv := range op.metric {
+				lp := metric.LabelPair{Name: ln, Value: lv}
+				baseFPs, ok := pairToFPs[lp]
+				if !ok {
+					var err error
+					baseFPs, _, err = p.labelPairToFingerprints.LookupSet(lp)
+					if err != nil {
+						glog.Errorf("Error looking up label pair %v: %s", lp, err)
+						continue
+					}
+					pairToFPs[lp] = baseFPs
+				}
+				baseValues, ok := nameToValues[ln]
+				if !ok {
+					var err error
+					baseValues, _, err = p.labelNameToLabelValues.LookupSet(ln)
+					if err != nil {
+						glog.Errorf("Error looking up label name %v: %s", ln, err)
+						continue
+					}
+					nameToValues[ln] = baseValues
+				}
+				switch op.opType {
+				case add:
+					baseFPs[op.fingerprint] = struct{}{}
+					baseValues[lv] = struct{}{}
+				case remove:
+					delete(baseFPs, op.fingerprint)
+					if len(baseFPs) == 0 {
+						delete(baseValues, lv)
+					}
+				default:
+					panic("unknown op type")
+				}
+			}
+
+			if batchSize >= indexingMaxBatchSize {
+				commitBatch()
+			}
+			batchTimeout.Reset(indexingBatchTimeout)
+		}
+	}
+	close(p.indexingStopped)
+}
+
 // exists returns true when the given file or directory exists.
 func exists(path string) (bool, error) {
 	_, err := os.Stat(path)
diff --git a/storage/local/persistence_test.go b/storage/local/persistence_test.go
index 3ef92e949e..525c74bf38 100644
--- a/storage/local/persistence_test.go
+++ b/storage/local/persistence_test.go
@@ -14,11 +14,13 @@
 package local
 
 import (
-	"sort"
+	"reflect"
 	"testing"
+	"time"
 
 	clientmodel "github.com/prometheus/client_golang/model"
 
+	"github.com/prometheus/prometheus/storage/local/codable"
 	"github.com/prometheus/prometheus/storage/local/index"
 	"github.com/prometheus/prometheus/storage/metric"
 	"github.com/prometheus/prometheus/utility/test"
@@ -130,36 +132,46 @@ func TestIndexing(t *testing.T) {
 				},
 			},
 			expectedLnToLvs: index.LabelNameLabelValuesMapping{
-				clientmodel.MetricNameLabel: clientmodel.LabelValues{"metric_0", "metric_1"},
-				"label_1":                   clientmodel.LabelValues{"value_1", "value_2"},
-				"label_2":                   clientmodel.LabelValues{"value_2"},
-				"label_3":                   clientmodel.LabelValues{"value_3"},
+				clientmodel.MetricNameLabel: codable.LabelValueSet{
+					"metric_0": struct{}{},
+					"metric_1": struct{}{},
+				},
+				"label_1": codable.LabelValueSet{
+					"value_1": struct{}{},
+					"value_2": struct{}{},
+				},
+				"label_2": codable.LabelValueSet{
+					"value_2": struct{}{},
+				},
+				"label_3": codable.LabelValueSet{
+					"value_3": struct{}{},
+				},
 			},
 			expectedLpToFps: index.LabelPairFingerprintsMapping{
 				metric.LabelPair{
 					Name:  clientmodel.MetricNameLabel,
 					Value: "metric_0",
-				}: {0, 1},
+				}: codable.FingerprintSet{0: struct{}{}, 1: struct{}{}},
 				metric.LabelPair{
 					Name:  clientmodel.MetricNameLabel,
 					Value: "metric_1",
-				}: {2},
+				}: codable.FingerprintSet{2: struct{}{}},
 				metric.LabelPair{
 					Name:  "label_1",
 					Value: "value_1",
-				}: {0},
+				}: codable.FingerprintSet{0: struct{}{}},
 				metric.LabelPair{
 					Name:  "label_1",
 					Value: "value_2",
-				}: {2},
+				}: codable.FingerprintSet{2: struct{}{}},
 				metric.LabelPair{
 					Name:  "label_2",
 					Value: "value_2",
-				}: {1},
+				}: codable.FingerprintSet{1: struct{}{}},
 				metric.LabelPair{
 					Name:  "label_3",
 					Value: "value_3",
-				}: {1},
+				}: codable.FingerprintSet{1: struct{}{}},
 			},
 		}, {
 			fpToMetric: index.FingerprintMetricMapping{
@@ -178,48 +190,61 @@ func TestIndexing(t *testing.T) {
 				},
 			},
 			expectedLnToLvs: index.LabelNameLabelValuesMapping{
-				clientmodel.MetricNameLabel: clientmodel.LabelValues{"metric_0", "metric_1", "metric_2"},
-				"label_1":                   clientmodel.LabelValues{"value_1", "value_2", "value_3"},
-				"label_2":                   clientmodel.LabelValues{"value_2"},
-				"label_3":                   clientmodel.LabelValues{"value_1", "value_3"},
+				clientmodel.MetricNameLabel: codable.LabelValueSet{
+					"metric_0": struct{}{},
+					"metric_1": struct{}{},
+					"metric_2": struct{}{},
+				},
+				"label_1": codable.LabelValueSet{
+					"value_1": struct{}{},
+					"value_2": struct{}{},
+					"value_3": struct{}{},
+				},
+				"label_2": codable.LabelValueSet{
+					"value_2": struct{}{},
+				},
+				"label_3": codable.LabelValueSet{
+					"value_1": struct{}{},
+					"value_3": struct{}{},
+				},
 			},
 			expectedLpToFps: index.LabelPairFingerprintsMapping{
 				metric.LabelPair{
 					Name:  clientmodel.MetricNameLabel,
 					Value: "metric_0",
-				}: {0, 1, 3},
+				}: codable.FingerprintSet{0: struct{}{}, 1: struct{}{}, 3: struct{}{}},
 				metric.LabelPair{
 					Name:  clientmodel.MetricNameLabel,
 					Value: "metric_1",
-				}: {2, 5},
+				}: codable.FingerprintSet{2: struct{}{}, 5: struct{}{}},
 				metric.LabelPair{
 					Name:  clientmodel.MetricNameLabel,
 					Value: "metric_2",
-				}: {4},
+				}: codable.FingerprintSet{4: struct{}{}},
 				metric.LabelPair{
 					Name:  "label_1",
 					Value: "value_1",
-				}: {0},
+				}: codable.FingerprintSet{0: struct{}{}},
 				metric.LabelPair{
 					Name:  "label_1",
 					Value: "value_2",
-				}: {2},
+				}: codable.FingerprintSet{2: struct{}{}},
 				metric.LabelPair{
 					Name:  "label_1",
 					Value: "value_3",
-				}: {3, 5},
+				}: codable.FingerprintSet{3: struct{}{}, 5: struct{}{}},
 				metric.LabelPair{
 					Name:  "label_2",
 					Value: "value_2",
-				}: {1, 4},
+				}: codable.FingerprintSet{1: struct{}{}, 4: struct{}{}},
 				metric.LabelPair{
 					Name:  "label_3",
 					Value: "value_1",
-				}: {4},
+				}: codable.FingerprintSet{4: struct{}{}},
 				metric.LabelPair{
 					Name:  "label_3",
 					Value: "value_3",
-				}: {1},
+				}: codable.FingerprintSet{1: struct{}{}},
 			},
 		},
 	}
@@ -230,24 +255,24 @@ func TestIndexing(t *testing.T) {
 	indexedFpsToMetrics := index.FingerprintMetricMapping{}
 	for i, b := range batches {
 		for fp, m := range b.fpToMetric {
-			if err := p.IndexMetric(m, fp); err != nil {
-				t.Fatal(err)
-			}
+			p.IndexMetric(m, fp)
 			if err := p.ArchiveMetric(fp, m, 1, 2); err != nil {
 				t.Fatal(err)
 			}
 			indexedFpsToMetrics[fp] = m
 		}
+		// TODO: Find a better solution than sleeping.
+		time.Sleep(2 * indexingBatchTimeout)
 		verifyIndexedState(i, t, b, indexedFpsToMetrics, p.(*diskPersistence))
 	}
 
 	for i := len(batches) - 1; i >= 0; i-- {
 		b := batches[i]
+		// TODO: Find a better solution than sleeping.
+		time.Sleep(2 * indexingBatchTimeout)
 		verifyIndexedState(i, t, batches[i], indexedFpsToMetrics, p.(*diskPersistence))
 		for fp, m := range b.fpToMetric {
-			if err := p.UnindexMetric(m, fp); err != nil {
-				t.Fatal(err)
-			}
+			p.UnindexMetric(m, fp)
 			unarchived, err := p.UnarchiveMetric(fp)
 			if err != nil {
 				t.Fatal(err)
@@ -294,16 +319,13 @@ func verifyIndexedState(i int, t *testing.T, b incrementalBatch, indexedFpsToMet
 			t.Fatal(err)
 		}
 
-		sort.Sort(lvs)
-		sort.Sort(outLvs)
-
-		if len(lvs) != len(outLvs) {
-			t.Errorf("%d. different number of label values. Got: %d; want %d", i, len(outLvs), len(lvs))
+		outSet := codable.LabelValueSet{}
+		for _, lv := range outLvs {
+			outSet[lv] = struct{}{}
 		}
-		for j := range lvs {
-			if lvs[j] != outLvs[j] {
-				t.Errorf("%d.%d. label values don't match. Got: %s; want %s", i, j, outLvs[j], lvs[j])
-			}
+
+		if !reflect.DeepEqual(lvs, outSet) {
+			t.Errorf("%d. label values don't match. Got: %v; want %v", i, outSet, lvs)
 		}
 	}
 
@@ -314,16 +336,13 @@ func verifyIndexedState(i int, t *testing.T, b incrementalBatch, indexedFpsToMet
 			t.Fatal(err)
 		}
 
-		sort.Sort(fps)
-		sort.Sort(outFps)
-
-		if len(fps) != len(outFps) {
-			t.Errorf("%d. %v: different number of fingerprints. Got: %d; want %d", i, lp, len(outFps), len(fps))
+		outSet := codable.FingerprintSet{}
+		for _, fp := range outFps {
+			outSet[fp] = struct{}{}
 		}
-		for j := range fps {
-			if fps[j] != outFps[j] {
-				t.Errorf("%d.%d. %v: fingerprints don't match. Got: %d; want %d", i, j, lp, outFps[j], fps[j])
-			}
+
+		if !reflect.DeepEqual(fps, outSet) {
+			t.Errorf("%d. %v: fingerprints don't match. Got: %v; want %v", i, lp, outSet, fps)
 		}
 	}
 }
diff --git a/storage/local/storage.go b/storage/local/storage.go
index 115b50a4d2..a803aa1bd7 100644
--- a/storage/local/storage.go
+++ b/storage/local/storage.go
@@ -149,9 +149,7 @@ func (s *memorySeriesStorage) getOrCreateSeries(m clientmodel.Metric) *memorySer
 			series.headChunkPersisted = true
 		} else {
 			// This was a genuinely new series, so index the metric.
-			if err := s.persistence.IndexMetric(m, fp); err != nil {
-				glog.Errorf("Error indexing metric %v: %v", m, err)
-			}
+			s.persistence.IndexMetric(m, fp)
 		}
 	}
 	return series
@@ -362,9 +360,7 @@ func (s *memorySeriesStorage) purgeSeries(fp clientmodel.Fingerprint, beforeTime
 	if series, ok := s.fingerprintToSeries[fp]; ok {
 		if series.purgeOlderThan(beforeTime) && allDropped {
 			delete(s.fingerprintToSeries, fp)
-			if err := s.persistence.UnindexMetric(series.metric, fp); err != nil {
-				glog.Errorf("Error unindexing metric %v: %v", series.metric, err)
-			}
+			s.persistence.UnindexMetric(series.metric, fp)
 		}
 		return
 	}