diff --git a/promql/analyzer.go b/promql/analyzer.go
index 32bdc64ed..b1695b7a4 100644
--- a/promql/analyzer.go
+++ b/promql/analyzer.go
@@ -73,7 +73,7 @@ func (a *Analyzer) Analyze(ctx context.Context) error {
 		switch n := node.(type) {
 		case *VectorSelector:
 			pt := getPreloadTimes(n.Offset)
-			fpts := a.Storage.GetFingerprintsForLabelMatchers(n.LabelMatchers)
+			fpts := a.Storage.FingerprintsForLabelMatchers(n.LabelMatchers)
 			n.fingerprints = fpts
 			n.metrics = map[clientmodel.Fingerprint]clientmodel.COWMetric{}
 			n.iterators = map[clientmodel.Fingerprint]local.SeriesIterator{}
@@ -84,11 +84,11 @@ func (a *Analyzer) Analyze(ctx context.Context) error {
 				if _, alreadyInRanges := pt.ranges[fp]; !alreadyInRanges {
 					pt.instants[fp] = struct{}{}
 				}
-				n.metrics[fp] = a.Storage.GetMetricForFingerprint(fp)
+				n.metrics[fp] = a.Storage.MetricForFingerprint(fp)
 			}
 		case *MatrixSelector:
 			pt := getPreloadTimes(n.Offset)
-			fpts := a.Storage.GetFingerprintsForLabelMatchers(n.LabelMatchers)
+			fpts := a.Storage.FingerprintsForLabelMatchers(n.LabelMatchers)
 			n.fingerprints = fpts
 			n.metrics = map[clientmodel.Fingerprint]clientmodel.COWMetric{}
 			n.iterators = map[clientmodel.Fingerprint]local.SeriesIterator{}
@@ -100,7 +100,7 @@ func (a *Analyzer) Analyze(ctx context.Context) error {
 					// an instant for the same fingerprint, should we have one.
 					delete(pt.instants, fp)
 				}
-				n.metrics[fp] = a.Storage.GetMetricForFingerprint(fp)
+				n.metrics[fp] = a.Storage.MetricForFingerprint(fp)
 			}
 		}
 		return true
diff --git a/promql/engine.go b/promql/engine.go
index 08e49f25c..1b2dc2a89 100644
--- a/promql/engine.go
+++ b/promql/engine.go
@@ -644,7 +644,7 @@ func (ev *evaluator) eval(expr Expr) Value {
 func (ev *evaluator) vectorSelector(node *VectorSelector) Vector {
 	vec := Vector{}
 	for fp, it := range node.iterators {
-		sampleCandidates := it.GetValueAtTime(ev.Timestamp.Add(-node.Offset))
+		sampleCandidates := it.ValueAtTime(ev.Timestamp.Add(-node.Offset))
 		samplePair := chooseClosestSample(sampleCandidates, ev.Timestamp.Add(-node.Offset))
 		if samplePair != nil {
 			vec = append(vec, &Sample{
@@ -666,7 +666,7 @@ func (ev *evaluator) matrixSelector(node *MatrixSelector) Matrix {
 
 	sampleStreams := make([]*SampleStream, 0, len(node.iterators))
 	for fp, it := range node.iterators {
-		samplePairs := it.GetRangeValues(interval)
+		samplePairs := it.RangeValues(interval)
 		if len(samplePairs) == 0 {
 			continue
 		}
@@ -695,7 +695,7 @@ func (ev *evaluator) matrixSelectorBounds(node *MatrixSelector) Matrix {
 
 	sampleStreams := make([]*SampleStream, 0, len(node.iterators))
 	for fp, it := range node.iterators {
-		samplePairs := it.GetBoundaryValues(interval)
+		samplePairs := it.BoundaryValues(interval)
 		if len(samplePairs) == 0 {
 			continue
 		}
diff --git a/storage/local/chunk.go b/storage/local/chunk.go
index e1bac7f8b..e911e4260 100644
--- a/storage/local/chunk.go
+++ b/storage/local/chunk.go
@@ -41,8 +41,8 @@ const (
 // goroutine-safe proxies for chunk methods.
 type chunkDesc struct {
 	sync.Mutex
-	chunk          chunk // nil if chunk is evicted.
-	refCount       int
+	c              chunk // nil if chunk is evicted.
+	rCnt           int
 	chunkFirstTime clientmodel.Timestamp // Used if chunk is evicted.
 	chunkLastTime  clientmodel.Timestamp // Used if chunk is evicted.
 
@@ -59,14 +59,14 @@ func newChunkDesc(c chunk) *chunkDesc {
 	chunkOps.WithLabelValues(createAndPin).Inc()
 	atomic.AddInt64(&numMemChunks, 1)
 	numMemChunkDescs.Inc()
-	return &chunkDesc{chunk: c, refCount: 1}
+	return &chunkDesc{c: c, rCnt: 1}
 }
 
 func (cd *chunkDesc) add(s *metric.SamplePair) []chunk {
 	cd.Lock()
 	defer cd.Unlock()
 
-	return cd.chunk.add(s)
+	return cd.c.add(s)
 }
 
 // pin increments the refCount by one. Upon increment from 0 to 1, this
@@ -76,11 +76,11 @@ func (cd *chunkDesc) pin(evictRequests chan<- evictRequest) {
 	cd.Lock()
 	defer cd.Unlock()
 
-	if cd.refCount == 0 {
+	if cd.rCnt == 0 {
 		// Remove ourselves from the evict list.
 		evictRequests <- evictRequest{cd, false}
 	}
-	cd.refCount++
+	cd.rCnt++
 }
 
 // unpin decrements the refCount by one. Upon decrement from 1 to 0, this
@@ -90,69 +90,69 @@ func (cd *chunkDesc) unpin(evictRequests chan<- evictRequest) {
 	cd.Lock()
 	defer cd.Unlock()
 
-	if cd.refCount == 0 {
+	if cd.rCnt == 0 {
 		panic("cannot unpin already unpinned chunk")
 	}
-	cd.refCount--
-	if cd.refCount == 0 {
+	cd.rCnt--
+	if cd.rCnt == 0 {
 		// Add ourselves to the back of the evict list.
 		evictRequests <- evictRequest{cd, true}
 	}
 }
 
-func (cd *chunkDesc) getRefCount() int {
+func (cd *chunkDesc) refCount() int {
 	cd.Lock()
 	defer cd.Unlock()
 
-	return cd.refCount
+	return cd.rCnt
 }
 
 func (cd *chunkDesc) firstTime() clientmodel.Timestamp {
 	cd.Lock()
 	defer cd.Unlock()
 
-	if cd.chunk == nil {
+	if cd.c == nil {
 		return cd.chunkFirstTime
 	}
-	return cd.chunk.firstTime()
+	return cd.c.firstTime()
 }
 
 func (cd *chunkDesc) lastTime() clientmodel.Timestamp {
 	cd.Lock()
 	defer cd.Unlock()
 
-	if cd.chunk == nil {
+	if cd.c == nil {
 		return cd.chunkLastTime
 	}
-	return cd.chunk.lastTime()
+	return cd.c.newIterator().lastTimestamp()
 }
 
 func (cd *chunkDesc) isEvicted() bool {
 	cd.Lock()
 	defer cd.Unlock()
 
-	return cd.chunk == nil
+	return cd.c == nil
 }
 
 func (cd *chunkDesc) contains(t clientmodel.Timestamp) bool {
 	return !t.Before(cd.firstTime()) && !t.After(cd.lastTime())
 }
 
-func (cd *chunkDesc) getChunk() chunk {
+func (cd *chunkDesc) chunk() chunk {
 	cd.Lock()
 	defer cd.Unlock()
 
-	return cd.chunk
+	return cd.c
 }
 
 func (cd *chunkDesc) setChunk(c chunk) {
 	cd.Lock()
 	defer cd.Unlock()
 
-	if cd.chunk != nil {
+	if cd.c != nil {
 		panic("chunk already set")
 	}
-	cd.chunk = c
+	cd.c = c
 }
 
 // maybeEvict evicts the chunk if the refCount is 0. It returns whether the chunk
@@ -162,15 +162,15 @@ func (cd *chunkDesc) maybeEvict() bool {
 	cd.Lock()
 	defer cd.Unlock()
 
-	if cd.chunk == nil {
+	if cd.c == nil {
 		return true
 	}
-	if cd.refCount != 0 {
+	if cd.rCnt != 0 {
 		return false
 	}
-	cd.chunkFirstTime = cd.chunk.firstTime()
-	cd.chunkLastTime = cd.chunk.lastTime()
-	cd.chunk = nil
+	cd.chunkFirstTime = cd.c.firstTime()
+	cd.chunkLastTime = cd.c.newIterator().lastTimestamp()
+	cd.c = nil
 	chunkOps.WithLabelValues(evict).Inc()
 	atomic.AddInt64(&numMemChunks, -1)
 	return true
@@ -188,12 +188,38 @@ type chunk interface {
 	add(sample *metric.SamplePair) []chunk
 	clone() chunk
 	firstTime() clientmodel.Timestamp
-	lastTime() clientmodel.Timestamp
 	newIterator() chunkIterator
 	marshal(io.Writer) error
 	unmarshal(io.Reader) error
 	unmarshalFromBuf([]byte)
 	encoding() chunkEncoding
+}
+
+// A chunkIterator enables efficient access to the content of a chunk. It is
+// generally not safe to use a chunkIterator concurrently with or after chunk
+// mutation.
+type chunkIterator interface {
+	// length returns the number of samples in the chunk.
+	length() int
+	// Gets the timestamp of the n-th sample in the chunk.
+	timestampAtIndex(int) clientmodel.Timestamp
+	// Gets the last timestamp in the chunk.
+	lastTimestamp() clientmodel.Timestamp
+	// Gets the sample value of the n-th sample in the chunk.
+	sampleValueAtIndex(int) clientmodel.SampleValue
+	// Gets the last sample value in the chunk.
+	lastSampleValue() clientmodel.SampleValue
+	// Gets the two values that are immediately adjacent to a given time. In
+	// case a value exist at precisely the given time, only that single
+	// value is returned. Only the first or last value is returned (as a
+	// single value), if the given time is before or after the first or last
+	// value, respectively.
+	valueAtTime(clientmodel.Timestamp) metric.Values
+	// Gets all values contained within a given interval.
+	rangeValues(metric.Interval) metric.Values
+	// Whether a given timestamp is contained between first and last value
+	// in the chunk.
+	contains(clientmodel.Timestamp) bool
 	// values returns a channel, from which all sample values in the chunk
 	// can be received in order. The channel is closed after the last
 	// one. It is generally not safe to mutate the chunk while the channel
@@ -201,29 +227,12 @@ type chunk interface {
 	values() <-chan *metric.SamplePair
 }
 
-// A chunkIterator enables efficient access to the content of a chunk. It is
-// generally not safe to use a chunkIterator concurrently with or after chunk
-// mutation.
-type chunkIterator interface {
-	// Gets the two values that are immediately adjacent to a given time. In
-	// case a value exist at precisely the given time, only that single
-	// value is returned. Only the first or last value is returned (as a
-	// single value), if the given time is before or after the first or last
-	// value, respectively.
-	getValueAtTime(clientmodel.Timestamp) metric.Values
-	// Gets all values contained within a given interval.
-	getRangeValues(metric.Interval) metric.Values
-	// Whether a given timestamp is contained between first and last value
-	// in the chunk.
-	contains(clientmodel.Timestamp) bool
-}
-
 func transcodeAndAdd(dst chunk, src chunk, s *metric.SamplePair) []chunk {
 	chunkOps.WithLabelValues(transcode).Inc()
 
 	head := dst
 	body := []chunk{}
-	for v := range src.values() {
+	for v := range src.newIterator().values() {
 		newChunks := head.add(v)
 		body = append(body, newChunks[:len(newChunks)-1]...)
 		head = newChunks[len(newChunks)-1]
diff --git a/storage/local/crashrecovery.go b/storage/local/crashrecovery.go
index 25f656666..d52bdfcb0 100644
--- a/storage/local/crashrecovery.go
+++ b/storage/local/crashrecovery.go
@@ -318,7 +318,7 @@ func (p *persistence) sanitizeSeries(
 		return fp, true
 	}
 	// This series is supposed to be archived.
-	metric, err := p.getArchivedMetric(fp)
+	metric, err := p.archivedMetric(fp)
 	if err != nil {
 		log.Errorf(
 			"Fingerprint %v assumed archived but couldn't be looked up in archived index: %s",
diff --git a/storage/local/delta.go b/storage/local/delta.go
index 1be169feb..9e04890fe 100644
--- a/storage/local/delta.go
+++ b/storage/local/delta.go
@@ -188,18 +188,19 @@ func (c deltaEncodedChunk) clone() chunk {
 
 // firstTime implements chunk.
 func (c deltaEncodedChunk) firstTime() clientmodel.Timestamp {
-	return c.valueAtIndex(0).Timestamp
-}
-
-// lastTime implements chunk.
-func (c deltaEncodedChunk) lastTime() clientmodel.Timestamp {
-	return c.valueAtIndex(c.len() - 1).Timestamp
+	return c.baseTime()
 }
 
 // newIterator implements chunk.
 func (c *deltaEncodedChunk) newIterator() chunkIterator {
 	return &deltaEncodedChunkIterator{
-		chunk: c,
+		c:      *c,
+		len:    c.len(),
+		baseT:  c.baseTime(),
+		baseV:  c.baseValue(),
+		tBytes: c.timeBytes(),
+		vBytes: c.valueBytes(),
+		isInt:  c.isInt(),
 	}
 }
 
@@ -237,19 +238,6 @@ func (c *deltaEncodedChunk) unmarshalFromBuf(buf []byte) {
 	*c = (*c)[:binary.LittleEndian.Uint16((*c)[deltaHeaderBufLenOffset:])]
 }
 
-// values implements chunk.
-func (c deltaEncodedChunk) values() <-chan *metric.SamplePair {
-	n := c.len()
-	valuesChan := make(chan *metric.SamplePair)
-	go func() {
-		for i := 0; i < n; i++ {
-			valuesChan <- c.valueAtIndex(i)
-		}
-		close(valuesChan)
-	}()
-	return valuesChan
-}
-
 // encoding implements chunk.
 func (c deltaEncodedChunk) encoding() chunkEncoding { return delta }
 
@@ -284,106 +272,157 @@ func (c deltaEncodedChunk) len() int {
 	return (len(c) - deltaHeaderBytes) / c.sampleSize()
 }
 
-func (c deltaEncodedChunk) valueAtIndex(idx int) *metric.SamplePair {
-	offset := deltaHeaderBytes + idx*c.sampleSize()
-
-	var ts clientmodel.Timestamp
-	switch c.timeBytes() {
-	case d1:
-		ts = c.baseTime() + clientmodel.Timestamp(uint8(c[offset]))
-	case d2:
-		ts = c.baseTime() + clientmodel.Timestamp(binary.LittleEndian.Uint16(c[offset:]))
-	case d4:
-		ts = c.baseTime() + clientmodel.Timestamp(binary.LittleEndian.Uint32(c[offset:]))
-	case d8:
-		// Take absolute value for d8.
-		ts = clientmodel.Timestamp(binary.LittleEndian.Uint64(c[offset:]))
-	default:
-		panic("Invalid number of bytes for time delta")
-	}
-
-	offset += int(c.timeBytes())
-
-	var v clientmodel.SampleValue
-	if c.isInt() {
-		switch c.valueBytes() {
-		case d0:
-			v = c.baseValue()
-		case d1:
-			v = c.baseValue() + clientmodel.SampleValue(int8(c[offset]))
-		case d2:
-			v = c.baseValue() + clientmodel.SampleValue(int16(binary.LittleEndian.Uint16(c[offset:])))
-		case d4:
-			v = c.baseValue() + clientmodel.SampleValue(int32(binary.LittleEndian.Uint32(c[offset:])))
-		// No d8 for ints.
-		default:
-			panic("Invalid number of bytes for integer delta")
-		}
-	} else {
-		switch c.valueBytes() {
-		case d4:
-			v = c.baseValue() + clientmodel.SampleValue(math.Float32frombits(binary.LittleEndian.Uint32(c[offset:])))
-		case d8:
-			// Take absolute value for d8.
-			v = clientmodel.SampleValue(math.Float64frombits(binary.LittleEndian.Uint64(c[offset:])))
-		default:
-			panic("Invalid number of bytes for floating point delta")
-		}
-	}
-	return &metric.SamplePair{
-		Timestamp: ts,
-		Value:     v,
-	}
-}
-
 // deltaEncodedChunkIterator implements chunkIterator.
 type deltaEncodedChunkIterator struct {
-	chunk *deltaEncodedChunk
-	// TODO: add more fields here to keep track of last position.
+	c              deltaEncodedChunk
+	len            int
+	baseT          clientmodel.Timestamp
+	baseV          clientmodel.SampleValue
+	tBytes, vBytes deltaBytes
+	isInt          bool
 }
 
-// getValueAtTime implements chunkIterator.
-func (it *deltaEncodedChunkIterator) getValueAtTime(t clientmodel.Timestamp) metric.Values {
-	i := sort.Search(it.chunk.len(), func(i int) bool {
-		return !it.chunk.valueAtIndex(i).Timestamp.Before(t)
+// length implements chunkIterator.
+func (it *deltaEncodedChunkIterator) length() int { return it.len }
+
+// valueAtTime implements chunkIterator.
+func (it *deltaEncodedChunkIterator) valueAtTime(t clientmodel.Timestamp) metric.Values {
+	i := sort.Search(it.len, func(i int) bool {
+		return !it.timestampAtIndex(i).Before(t)
 	})
 
 	switch i {
 	case 0:
-		return metric.Values{*it.chunk.valueAtIndex(0)}
-	case it.chunk.len():
-		return metric.Values{*it.chunk.valueAtIndex(it.chunk.len() - 1)}
+		return metric.Values{metric.SamplePair{
+			Timestamp: it.timestampAtIndex(0),
+			Value:     it.sampleValueAtIndex(0),
+		}}
+	case it.len:
+		return metric.Values{metric.SamplePair{
+			Timestamp: it.timestampAtIndex(it.len - 1),
+			Value:     it.sampleValueAtIndex(it.len - 1),
+		}}
 	default:
-		v := it.chunk.valueAtIndex(i)
-		if v.Timestamp.Equal(t) {
-			return metric.Values{*v}
+		ts := it.timestampAtIndex(i)
+		if ts.Equal(t) {
+			return metric.Values{metric.SamplePair{
+				Timestamp: ts,
+				Value:     it.sampleValueAtIndex(i),
+			}}
+		}
+		return metric.Values{
+			metric.SamplePair{
+				Timestamp: it.timestampAtIndex(i - 1),
+				Value:     it.sampleValueAtIndex(i - 1),
+			},
+			metric.SamplePair{
+				Timestamp: ts,
+				Value:     it.sampleValueAtIndex(i),
+			},
 		}
-		return metric.Values{*it.chunk.valueAtIndex(i - 1), *v}
 	}
 }
 
-// getRangeValues implements chunkIterator.
-func (it *deltaEncodedChunkIterator) getRangeValues(in metric.Interval) metric.Values {
-	oldest := sort.Search(it.chunk.len(), func(i int) bool {
-		return !it.chunk.valueAtIndex(i).Timestamp.Before(in.OldestInclusive)
+// rangeValues implements chunkIterator.
+func (it *deltaEncodedChunkIterator) rangeValues(in metric.Interval) metric.Values {
+	oldest := sort.Search(it.len, func(i int) bool {
+		return !it.timestampAtIndex(i).Before(in.OldestInclusive)
 	})
 
-	newest := sort.Search(it.chunk.len(), func(i int) bool {
-		return it.chunk.valueAtIndex(i).Timestamp.After(in.NewestInclusive)
+	newest := sort.Search(it.len, func(i int) bool {
+		return it.timestampAtIndex(i).After(in.NewestInclusive)
 	})
 
-	if oldest == it.chunk.len() {
+	if oldest == it.len {
 		return nil
 	}
 
 	result := make(metric.Values, 0, newest-oldest)
 	for i := oldest; i < newest; i++ {
-		result = append(result, *it.chunk.valueAtIndex(i))
+		result = append(result, metric.SamplePair{
+			Timestamp: it.timestampAtIndex(i),
+			Value:     it.sampleValueAtIndex(i),
+		})
 	}
 	return result
 }
 
 // contains implements chunkIterator.
 func (it *deltaEncodedChunkIterator) contains(t clientmodel.Timestamp) bool {
-	return !t.Before(it.chunk.firstTime()) && !t.After(it.chunk.lastTime())
+	return !t.Before(it.baseT) && !t.After(it.timestampAtIndex(it.len-1))
+}
+
+// values implements chunkIterator.
+func (it *deltaEncodedChunkIterator) values() <-chan *metric.SamplePair {
+	valuesChan := make(chan *metric.SamplePair)
+	go func() {
+		for i := 0; i < it.len; i++ {
+			valuesChan <- &metric.SamplePair{
+				Timestamp: it.timestampAtIndex(i),
+				Value:     it.sampleValueAtIndex(i),
+			}
+		}
+		close(valuesChan)
+	}()
+	return valuesChan
+}
+
+// timestampAtIndex implements chunkIterator.
+func (it *deltaEncodedChunkIterator) timestampAtIndex(idx int) clientmodel.Timestamp {
+	offset := deltaHeaderBytes + idx*int(it.tBytes+it.vBytes)
+
+	switch it.tBytes {
+	case d1:
+		return it.baseT + clientmodel.Timestamp(uint8(it.c[offset]))
+	case d2:
+		return it.baseT + clientmodel.Timestamp(binary.LittleEndian.Uint16(it.c[offset:]))
+	case d4:
+		return it.baseT + clientmodel.Timestamp(binary.LittleEndian.Uint32(it.c[offset:]))
+	case d8:
+		// Take absolute value for d8.
+		return clientmodel.Timestamp(binary.LittleEndian.Uint64(it.c[offset:]))
+	default:
+		panic("Invalid number of bytes for time delta")
+	}
+}
+
+// lastTimestamp implements chunkIterator.
+func (it *deltaEncodedChunkIterator) lastTimestamp() clientmodel.Timestamp {
+	return it.timestampAtIndex(it.len - 1)
+}
+
+// sampleValueAtIndex implements chunkIterator.
+func (it *deltaEncodedChunkIterator) sampleValueAtIndex(idx int) clientmodel.SampleValue {
+	offset := deltaHeaderBytes + idx*int(it.tBytes+it.vBytes) + int(it.tBytes)
+
+	if it.isInt {
+		switch it.vBytes {
+		case d0:
+			return it.baseV
+		case d1:
+			return it.baseV + clientmodel.SampleValue(int8(it.c[offset]))
+		case d2:
+			return it.baseV + clientmodel.SampleValue(int16(binary.LittleEndian.Uint16(it.c[offset:])))
+		case d4:
+			return it.baseV + clientmodel.SampleValue(int32(binary.LittleEndian.Uint32(it.c[offset:])))
+		// No d8 for ints.
+		default:
+			panic("Invalid number of bytes for integer delta")
+		}
+	} else {
+		switch it.vBytes {
+		case d4:
+			return it.baseV + clientmodel.SampleValue(math.Float32frombits(binary.LittleEndian.Uint32(it.c[offset:])))
+		case d8:
+			// Take absolute value for d8.
+			return clientmodel.SampleValue(math.Float64frombits(binary.LittleEndian.Uint64(it.c[offset:])))
+		default:
+			panic("Invalid number of bytes for floating point delta")
+		}
+	}
+}
+
+// lastSampleValue implements chunkIterator.
+func (it *deltaEncodedChunkIterator) lastSampleValue() clientmodel.SampleValue {
+	return it.sampleValueAtIndex(it.len - 1)
 }
diff --git a/storage/local/doubledelta.go b/storage/local/doubledelta.go
index dcfd155ed..17e2aa5f6 100644
--- a/storage/local/doubledelta.go
+++ b/storage/local/doubledelta.go
@@ -199,15 +199,18 @@ func (c doubleDeltaEncodedChunk) firstTime() clientmodel.Timestamp {
 	return c.baseTime()
 }
 
-// lastTime implements chunk.
-func (c doubleDeltaEncodedChunk) lastTime() clientmodel.Timestamp {
-	return c.valueAtIndex(c.len() - 1).Timestamp
-}
-
 // newIterator implements chunk.
 func (c *doubleDeltaEncodedChunk) newIterator() chunkIterator {
 	return &doubleDeltaEncodedChunkIterator{
-		chunk: c,
+		c:      *c,
+		len:    c.len(),
+		baseT:  c.baseTime(),
+		baseΔT: c.baseTimeDelta(),
+		baseV:  c.baseValue(),
+		baseΔV: c.baseValueDelta(),
+		tBytes: c.timeBytes(),
+		vBytes: c.valueBytes(),
+		isInt:  c.isInt(),
 	}
 }
 
@@ -245,19 +248,6 @@ func (c *doubleDeltaEncodedChunk) unmarshalFromBuf(buf []byte) {
 	*c = (*c)[:binary.LittleEndian.Uint16((*c)[doubleDeltaHeaderBufLenOffset:])]
 }
 
-// values implements chunk.
-func (c doubleDeltaEncodedChunk) values() <-chan *metric.SamplePair {
-	n := c.len()
-	valuesChan := make(chan *metric.SamplePair)
-	go func() {
-		for i := 0; i < n; i++ {
-			valuesChan <- c.valueAtIndex(i)
-		}
-		close(valuesChan)
-	}()
-	return valuesChan
-}
-
 // encoding implements chunk.
 func (c doubleDeltaEncodedChunk) encoding() chunkEncoding { return doubleDelta }
 
@@ -280,6 +270,9 @@ func (c doubleDeltaEncodedChunk) baseValue() clientmodel.SampleValue {
 }
 
 func (c doubleDeltaEncodedChunk) baseTimeDelta() clientmodel.Timestamp {
+	if len(c) < doubleDeltaHeaderBaseTimeDeltaOffset+8 {
+		return 0
+	}
 	return clientmodel.Timestamp(
 		binary.LittleEndian.Uint64(
 			c[doubleDeltaHeaderBaseTimeDeltaOffset:],
@@ -288,6 +281,9 @@ func (c doubleDeltaEncodedChunk) baseTimeDelta() clientmodel.Timestamp {
 }
 
 func (c doubleDeltaEncodedChunk) baseValueDelta() clientmodel.SampleValue {
+	if len(c) < doubleDeltaHeaderBaseValueDeltaOffset+8 {
+		return 0
+	}
 	return clientmodel.SampleValue(
 		math.Float64frombits(
 			binary.LittleEndian.Uint64(
@@ -387,147 +383,196 @@ func (c doubleDeltaEncodedChunk) addSecondSample(s *metric.SamplePair, tb, vb de
 	return []chunk{&c}
 }
 
-func (c doubleDeltaEncodedChunk) valueAtIndex(idx int) *metric.SamplePair {
-	if idx == 0 {
-		return &metric.SamplePair{
-			Timestamp: c.baseTime(),
-			Value:     c.baseValue(),
-		}
-	}
-	if idx == 1 {
-		// If time and/or value bytes are at d8, the time and value is
-		// saved directly rather than as a difference.
-		timestamp := c.baseTimeDelta()
-		if c.timeBytes() < d8 {
-			timestamp += c.baseTime()
-		}
-		value := c.baseValueDelta()
-		if c.valueBytes() < d8 {
-			value += c.baseValue()
-		}
-		return &metric.SamplePair{
-			Timestamp: timestamp,
-			Value:     value,
-		}
-	}
-	offset := doubleDeltaHeaderBytes + (idx-2)*c.sampleSize()
-
-	var ts clientmodel.Timestamp
-	switch c.timeBytes() {
-	case d1:
-		ts = c.baseTime() +
-			clientmodel.Timestamp(idx)*c.baseTimeDelta() +
-			clientmodel.Timestamp(int8(c[offset]))
-	case d2:
-		ts = c.baseTime() +
-			clientmodel.Timestamp(idx)*c.baseTimeDelta() +
-			clientmodel.Timestamp(int16(binary.LittleEndian.Uint16(c[offset:])))
-	case d4:
-		ts = c.baseTime() +
-			clientmodel.Timestamp(idx)*c.baseTimeDelta() +
-			clientmodel.Timestamp(int32(binary.LittleEndian.Uint32(c[offset:])))
-	case d8:
-		// Take absolute value for d8.
-		ts = clientmodel.Timestamp(binary.LittleEndian.Uint64(c[offset:]))
-	default:
-		panic("Invalid number of bytes for time delta")
-	}
-
-	offset += int(c.timeBytes())
-
-	var v clientmodel.SampleValue
-	if c.isInt() {
-		switch c.valueBytes() {
-		case d0:
-			v = c.baseValue() +
-				clientmodel.SampleValue(idx)*c.baseValueDelta()
-		case d1:
-			v = c.baseValue() +
-				clientmodel.SampleValue(idx)*c.baseValueDelta() +
-				clientmodel.SampleValue(int8(c[offset]))
-		case d2:
-			v = c.baseValue() +
-				clientmodel.SampleValue(idx)*c.baseValueDelta() +
-				clientmodel.SampleValue(int16(binary.LittleEndian.Uint16(c[offset:])))
-		case d4:
-			v = c.baseValue() +
-				clientmodel.SampleValue(idx)*c.baseValueDelta() +
-				clientmodel.SampleValue(int32(binary.LittleEndian.Uint32(c[offset:])))
-		// No d8 for ints.
-		default:
-			panic("Invalid number of bytes for integer delta")
-		}
-	} else {
-		switch c.valueBytes() {
-		case d4:
-			v = c.baseValue() +
-				clientmodel.SampleValue(idx)*c.baseValueDelta() +
-				clientmodel.SampleValue(math.Float32frombits(binary.LittleEndian.Uint32(c[offset:])))
-		case d8:
-			// Take absolute value for d8.
-			v = clientmodel.SampleValue(math.Float64frombits(binary.LittleEndian.Uint64(c[offset:])))
-		default:
-			panic("Invalid number of bytes for floating point delta")
-		}
-	}
-	return &metric.SamplePair{
-		Timestamp: ts,
-		Value:     v,
-	}
-}
-
 // doubleDeltaEncodedChunkIterator implements chunkIterator.
 type doubleDeltaEncodedChunkIterator struct {
-	chunk *doubleDeltaEncodedChunk
-	// TODO(beorn7): add more fields here to keep track of last position.
+	c              doubleDeltaEncodedChunk
+	len            int
+	baseT, baseΔT  clientmodel.Timestamp
+	baseV, baseΔV  clientmodel.SampleValue
+	tBytes, vBytes deltaBytes
+	isInt          bool
 }
 
-// getValueAtTime implements chunkIterator.
-func (it *doubleDeltaEncodedChunkIterator) getValueAtTime(t clientmodel.Timestamp) metric.Values {
-	// TODO(beorn7): Implement in a more efficient way making use of the
-	// state of the iterator and internals of the doubleDeltaChunk.
-	i := sort.Search(it.chunk.len(), func(i int) bool {
-		return !it.chunk.valueAtIndex(i).Timestamp.Before(t)
+// length implements chunkIterator.
+func (it *doubleDeltaEncodedChunkIterator) length() int { return it.len }
+
+// valueAtTime implements chunkIterator.
+func (it *doubleDeltaEncodedChunkIterator) valueAtTime(t clientmodel.Timestamp) metric.Values {
+	i := sort.Search(it.len, func(i int) bool {
+		return !it.timestampAtIndex(i).Before(t)
 	})
 
 	switch i {
 	case 0:
-		return metric.Values{*it.chunk.valueAtIndex(0)}
-	case it.chunk.len():
-		return metric.Values{*it.chunk.valueAtIndex(it.chunk.len() - 1)}
+		return metric.Values{metric.SamplePair{
+			Timestamp: it.timestampAtIndex(0),
+			Value:     it.sampleValueAtIndex(0),
+		}}
+	case it.len:
+		return metric.Values{metric.SamplePair{
+			Timestamp: it.timestampAtIndex(it.len - 1),
+			Value:     it.sampleValueAtIndex(it.len - 1),
+		}}
 	default:
-		v := it.chunk.valueAtIndex(i)
-		if v.Timestamp.Equal(t) {
-			return metric.Values{*v}
+		ts := it.timestampAtIndex(i)
+		if ts.Equal(t) {
+			return metric.Values{metric.SamplePair{
+				Timestamp: ts,
+				Value:     it.sampleValueAtIndex(i),
+			}}
+		}
+		return metric.Values{
+			metric.SamplePair{
+				Timestamp: it.timestampAtIndex(i - 1),
+				Value:     it.sampleValueAtIndex(i - 1),
+			},
+			metric.SamplePair{
+				Timestamp: ts,
+				Value:     it.sampleValueAtIndex(i),
+			},
 		}
-		return metric.Values{*it.chunk.valueAtIndex(i - 1), *v}
 	}
 }
 
-// getRangeValues implements chunkIterator.
-func (it *doubleDeltaEncodedChunkIterator) getRangeValues(in metric.Interval) metric.Values {
-	// TODO(beorn7): Implement in a more efficient way making use of the
-	// state of the iterator and internals of the doubleDeltaChunk.
-	oldest := sort.Search(it.chunk.len(), func(i int) bool {
-		return !it.chunk.valueAtIndex(i).Timestamp.Before(in.OldestInclusive)
+// rangeValues implements chunkIterator.
+func (it *doubleDeltaEncodedChunkIterator) rangeValues(in metric.Interval) metric.Values {
+	oldest := sort.Search(it.len, func(i int) bool {
+		return !it.timestampAtIndex(i).Before(in.OldestInclusive)
 	})
 
-	newest := sort.Search(it.chunk.len(), func(i int) bool {
-		return it.chunk.valueAtIndex(i).Timestamp.After(in.NewestInclusive)
+	newest := sort.Search(it.len, func(i int) bool {
+		return it.timestampAtIndex(i).After(in.NewestInclusive)
 	})
 
-	if oldest == it.chunk.len() {
+	if oldest == it.len {
 		return nil
 	}
 
 	result := make(metric.Values, 0, newest-oldest)
 	for i := oldest; i < newest; i++ {
-		result = append(result, *it.chunk.valueAtIndex(i))
+		result = append(result, metric.SamplePair{
+			Timestamp: it.timestampAtIndex(i),
+			Value:     it.sampleValueAtIndex(i),
+		})
 	}
 	return result
 }
 
 // contains implements chunkIterator.
 func (it *doubleDeltaEncodedChunkIterator) contains(t clientmodel.Timestamp) bool {
-	return !t.Before(it.chunk.firstTime()) && !t.After(it.chunk.lastTime())
+	return !t.Before(it.baseT) && !t.After(it.timestampAtIndex(it.len-1))
+}
+
+// values implements chunkIterator.
+func (it *doubleDeltaEncodedChunkIterator) values() <-chan *metric.SamplePair {
+	valuesChan := make(chan *metric.SamplePair)
+	go func() {
+		for i := 0; i < it.len; i++ {
+			valuesChan <- &metric.SamplePair{
+				Timestamp: it.timestampAtIndex(i),
+				Value:     it.sampleValueAtIndex(i),
+			}
+		}
+		close(valuesChan)
+	}()
+	return valuesChan
+}
+
+// timestampAtIndex implements chunkIterator.
+func (it *doubleDeltaEncodedChunkIterator) timestampAtIndex(idx int) clientmodel.Timestamp {
+	if idx == 0 {
+		return it.baseT
+	}
+	if idx == 1 {
+		// If time bytes are at d8, the time is saved directly rather
+		// than as a difference.
+		if it.tBytes == d8 {
+			return it.baseΔT
+		}
+		return it.baseT + it.baseΔT
+	}
+
+	offset := doubleDeltaHeaderBytes + (idx-2)*int(it.tBytes+it.vBytes)
+
+	switch it.tBytes {
+	case d1:
+		return it.baseT +
+			clientmodel.Timestamp(idx)*it.baseΔT +
+			clientmodel.Timestamp(int8(it.c[offset]))
+	case d2:
+		return it.baseT +
+			clientmodel.Timestamp(idx)*it.baseΔT +
+			clientmodel.Timestamp(int16(binary.LittleEndian.Uint16(it.c[offset:])))
+	case d4:
+		return it.baseT +
+			clientmodel.Timestamp(idx)*it.baseΔT +
+			clientmodel.Timestamp(int32(binary.LittleEndian.Uint32(it.c[offset:])))
+	case d8:
+		// Take absolute value for d8.
+		return clientmodel.Timestamp(binary.LittleEndian.Uint64(it.c[offset:]))
+	default:
+		panic("Invalid number of bytes for time delta")
+	}
+}
+
+// lastTimestamp implements chunkIterator.
+func (it *doubleDeltaEncodedChunkIterator) lastTimestamp() clientmodel.Timestamp {
+	return it.timestampAtIndex(it.len - 1)
+}
+
+// sampleValueAtIndex implements chunkIterator.
+func (it *doubleDeltaEncodedChunkIterator) sampleValueAtIndex(idx int) clientmodel.SampleValue {
+	if idx == 0 {
+		return it.baseV
+	}
+	if idx == 1 {
+		// If value bytes are at d8, the value is saved directly rather
+		// than as a difference.
+		if it.vBytes == d8 {
+			return it.baseΔV
+		}
+		return it.baseV + it.baseΔV
+	}
+
+	offset := doubleDeltaHeaderBytes + (idx-2)*int(it.tBytes+it.vBytes) + int(it.tBytes)
+
+	if it.isInt {
+		switch it.vBytes {
+		case d0:
+			return it.baseV +
+				clientmodel.SampleValue(idx)*it.baseΔV
+		case d1:
+			return it.baseV +
+				clientmodel.SampleValue(idx)*it.baseΔV +
+				clientmodel.SampleValue(int8(it.c[offset]))
+		case d2:
+			return it.baseV +
+				clientmodel.SampleValue(idx)*it.baseΔV +
+				clientmodel.SampleValue(int16(binary.LittleEndian.Uint16(it.c[offset:])))
+		case d4:
+			return it.baseV +
+				clientmodel.SampleValue(idx)*it.baseΔV +
+				clientmodel.SampleValue(int32(binary.LittleEndian.Uint32(it.c[offset:])))
+		// No d8 for ints.
+		default:
+			panic("Invalid number of bytes for integer delta")
+		}
+	} else {
+		switch it.vBytes {
+		case d4:
+			return it.baseV +
+				clientmodel.SampleValue(idx)*it.baseΔV +
+				clientmodel.SampleValue(math.Float32frombits(binary.LittleEndian.Uint32(it.c[offset:])))
+		case d8:
+			// Take absolute value for d8.
+			return clientmodel.SampleValue(math.Float64frombits(binary.LittleEndian.Uint64(it.c[offset:])))
+		default:
+			panic("Invalid number of bytes for floating point delta")
+		}
+	}
+}
+
+// lastSampleValue implements chunkIterator.
+func (it *doubleDeltaEncodedChunkIterator) lastSampleValue() clientmodel.SampleValue {
+	return it.sampleValueAtIndex(it.len - 1)
 }
diff --git a/storage/local/interface.go b/storage/local/interface.go
index 60df2d2f7..54885b0e2 100644
--- a/storage/local/interface.go
+++ b/storage/local/interface.go
@@ -38,11 +38,11 @@ type Storage interface {
 	NewPreloader() Preloader
 	// Get all of the metric fingerprints that are associated with the
 	// provided label matchers.
-	GetFingerprintsForLabelMatchers(metric.LabelMatchers) clientmodel.Fingerprints
+	FingerprintsForLabelMatchers(metric.LabelMatchers) clientmodel.Fingerprints
 	// Get all of the label values that are associated with a given label name.
-	GetLabelValuesForLabelName(clientmodel.LabelName) clientmodel.LabelValues
+	LabelValuesForLabelName(clientmodel.LabelName) clientmodel.LabelValues
 	// Get the metric associated with the provided fingerprint.
-	GetMetricForFingerprint(clientmodel.Fingerprint) clientmodel.COWMetric
+	MetricForFingerprint(clientmodel.Fingerprint) clientmodel.COWMetric
 	// Construct an iterator for a given fingerprint.
 	NewIterator(clientmodel.Fingerprint) SeriesIterator
 	// Run the various maintenance loops in goroutines. Returns when the
@@ -53,28 +53,28 @@ type Storage interface {
 	// operations, stops all maintenance loops,and frees all resources.
 	Stop() error
 	// WaitForIndexing returns once all samples in the storage are
-	// indexed. Indexing is needed for GetFingerprintsForLabelMatchers and
-	// GetLabelValuesForLabelName and may lag behind.
+	// indexed. Indexing is needed for FingerprintsForLabelMatchers and
+	// LabelValuesForLabelName and may lag behind.
 	WaitForIndexing()
 }
 
-// SeriesIterator enables efficient access of sample values in a series. All
-// methods are goroutine-safe. A SeriesIterator iterates over a snapshot of a
-// series, i.e. it is safe to continue using a SeriesIterator after modifying
-// the corresponding series, but the iterator will represent the state of the
-// series prior the modification.
+// SeriesIterator enables efficient access of sample values in a series. Its
+// methods are not goroutine-safe. A SeriesIterator iterates over a snapshot of
+// a series, i.e. it is safe to continue using a SeriesIterator after or during
+// modifying the corresponding series, but the iterator will represent the state
+// of the series prior the modification.
 type SeriesIterator interface {
 	// Gets the two values that are immediately adjacent to a given time. In
 	// case a value exist at precisely the given time, only that single
 	// value is returned. Only the first or last value is returned (as a
 	// single value), if the given time is before or after the first or last
 	// value, respectively.
-	GetValueAtTime(clientmodel.Timestamp) metric.Values
+	ValueAtTime(clientmodel.Timestamp) metric.Values
 	// Gets the boundary values of an interval: the first and last value
 	// within a given interval.
-	GetBoundaryValues(metric.Interval) metric.Values
+	BoundaryValues(metric.Interval) metric.Values
 	// Gets all values contained within a given interval.
-	GetRangeValues(metric.Interval) metric.Values
+	RangeValues(metric.Interval) metric.Values
 }
 
 // A Preloader preloads series data necessary for a query into memory and pins
diff --git a/storage/local/mapper.go b/storage/local/mapper.go
index 5fcb5cbfe..0dca894fa 100644
--- a/storage/local/mapper.go
+++ b/storage/local/mapper.go
@@ -93,7 +93,7 @@ func (r *fpMapper) mapFP(fp clientmodel.Fingerprint, m clientmodel.Metric) (clie
 	// If we are here, FP does not exist in memory and is either not mapped
 	// at all, or existing mappings for FP are not for m. Check if we have
 	// something for FP in the archive.
-	archivedMetric, err := r.p.getArchivedMetric(fp)
+	archivedMetric, err := r.p.archivedMetric(fp)
 	if err != nil {
 		return fp, err
 	}
diff --git a/storage/local/persistence.go b/storage/local/persistence.go
index b4828a8b8..c2fc3d034 100644
--- a/storage/local/persistence.go
+++ b/storage/local/persistence.go
@@ -319,11 +319,11 @@ func (p *persistence) setDirty(dirty bool) {
 	}
 }
 
-// getFingerprintsForLabelPair returns the fingerprints for the given label
+// fingerprintsForLabelPair returns the fingerprints for the given label
 // pair. This method is goroutine-safe but take into account that metrics queued
 // for indexing with IndexMetric might not have made it into the index
 // yet. (Same applies correspondingly to UnindexMetric.)
-func (p *persistence) getFingerprintsForLabelPair(lp metric.LabelPair) (clientmodel.Fingerprints, error) {
+func (p *persistence) fingerprintsForLabelPair(lp metric.LabelPair) (clientmodel.Fingerprints, error) {
 	fps, _, err := p.labelPairToFingerprints.Lookup(lp)
 	if err != nil {
 		return nil, err
@@ -331,11 +331,11 @@ func (p *persistence) getFingerprintsForLabelPair(lp metric.LabelPair) (clientmo
 	return fps, nil
 }
 
-// getLabelValuesForLabelName returns the label values for the given label
+// labelValuesForLabelName returns the label values for the given label
 // name. This method is goroutine-safe but take into account that metrics queued
 // for indexing with IndexMetric might not have made it into the index
 // yet. (Same applies correspondingly to UnindexMetric.)
-func (p *persistence) getLabelValuesForLabelName(ln clientmodel.LabelName) (clientmodel.LabelValues, error) {
+func (p *persistence) labelValuesForLabelName(ln clientmodel.LabelName) (clientmodel.LabelValues, error) {
 	lvs, _, err := p.labelNameToLabelValues.Lookup(ln)
 	if err != nil {
 		return nil, err
@@ -632,10 +632,10 @@ func (p *persistence) checkpointSeriesMapAndHeads(fingerprintToSeries *seriesMap
 					}
 				} else {
 					// This is the non-persisted head chunk. Fully marshal it.
-					if err = w.WriteByte(byte(chunkDesc.chunk.encoding())); err != nil {
+					if err = w.WriteByte(byte(chunkDesc.c.encoding())); err != nil {
 						return
 					}
-					if err = chunkDesc.chunk.marshal(w); err != nil {
+					if err = chunkDesc.c.marshal(w); err != nil {
 						return
 					}
 				}
@@ -880,7 +880,7 @@ func (p *persistence) dropAndPersistChunks(
 		// too old. If that's the case, the chunks in the series file
 		// are all too old, too.
 		i := 0
-		for ; i < len(chunks) && chunks[i].lastTime().Before(beforeTime); i++ {
+		for ; i < len(chunks) && chunks[i].newIterator().lastTimestamp().Before(beforeTime); i++ {
 		}
 		if i < len(chunks) {
 			firstTimeNotDropped = chunks[i].firstTime()
@@ -1017,10 +1017,10 @@ func (p *persistence) deleteSeriesFile(fp clientmodel.Fingerprint) (int, error)
 	return numChunks, nil
 }
 
-// getSeriesFileModTime returns the modification time of the series file
-// belonging to the provided fingerprint. In case of an error, the zero value of
-// time.Time is returned.
-func (p *persistence) getSeriesFileModTime(fp clientmodel.Fingerprint) time.Time {
+// seriesFileModTime returns the modification time of the series file belonging
+// to the provided fingerprint. In case of an error, the zero value of time.Time
+// is returned.
+func (p *persistence) seriesFileModTime(fp clientmodel.Fingerprint) time.Time {
 	var modTime time.Time
 	if fi, err := os.Stat(p.fileNameForFingerprint(fp)); err == nil {
 		return fi.ModTime()
@@ -1029,17 +1029,17 @@ func (p *persistence) getSeriesFileModTime(fp clientmodel.Fingerprint) time.Time
 }
 
 // indexMetric queues the given metric for addition to the indexes needed by
-// getFingerprintsForLabelPair, getLabelValuesForLabelName, and
-// getFingerprintsModifiedBefore.  If the queue is full, this method blocks
-// until the metric can be queued.  This method is goroutine-safe.
+// fingerprintsForLabelPair, labelValuesForLabelName, and
+// fingerprintsModifiedBefore.  If the queue is full, this method blocks until
+// the metric can be queued.  This method is goroutine-safe.
 func (p *persistence) indexMetric(fp clientmodel.Fingerprint, m clientmodel.Metric) {
 	p.indexingQueue <- indexingOp{fp, m, add}
 }
 
 // unindexMetric queues references to the given metric for removal from the
-// indexes used for getFingerprintsForLabelPair, getLabelValuesForLabelName, and
-// getFingerprintsModifiedBefore. The index of fingerprints to archived metrics
-// is not affected by this removal. (In fact, never call this method for an
+// indexes used for fingerprintsForLabelPair, labelValuesForLabelName, and
+// fingerprintsModifiedBefore. The index of fingerprints to archived metrics is
+// not affected by this removal. (In fact, never call this method for an
 // archived metric. To purge an archived metric, call purgeArchivedFingerprint.)
 // If the queue is full, this method blocks until the metric can be queued. This
 // method is goroutine-safe.
@@ -1097,10 +1097,10 @@ func (p *persistence) updateArchivedTimeRange(
 	return p.archivedFingerprintToTimeRange.Put(codable.Fingerprint(fp), codable.TimeRange{First: first, Last: last})
 }
 
-// getFingerprintsModifiedBefore returns the fingerprints of archived timeseries
+// fingerprintsModifiedBefore returns the fingerprints of archived timeseries
 // that have live samples before the provided timestamp. This method is
 // goroutine-safe.
-func (p *persistence) getFingerprintsModifiedBefore(beforeTime clientmodel.Timestamp) ([]clientmodel.Fingerprint, error) {
+func (p *persistence) fingerprintsModifiedBefore(beforeTime clientmodel.Timestamp) ([]clientmodel.Fingerprint, error) {
 	var fp codable.Fingerprint
 	var tr codable.TimeRange
 	fps := []clientmodel.Fingerprint{}
@@ -1119,9 +1119,9 @@ func (p *persistence) getFingerprintsModifiedBefore(beforeTime clientmodel.Times
 	return fps, nil
 }
 
-// getArchivedMetric retrieves the archived metric with the given
-// fingerprint. This method is goroutine-safe.
-func (p *persistence) getArchivedMetric(fp clientmodel.Fingerprint) (clientmodel.Metric, error) {
+// archivedMetric retrieves the archived metric with the given fingerprint. This
+// method is goroutine-safe.
+func (p *persistence) archivedMetric(fp clientmodel.Fingerprint) (clientmodel.Metric, error) {
 	metric, _, err := p.archivedFingerprintToMetrics.Lookup(fp)
 	return metric, err
 }
@@ -1137,7 +1137,7 @@ func (p *persistence) purgeArchivedMetric(fp clientmodel.Fingerprint) (err error
 		}
 	}()
 
-	metric, err := p.getArchivedMetric(fp)
+	metric, err := p.archivedMetric(fp)
 	if err != nil || metric == nil {
 		return err
 	}
@@ -1567,8 +1567,14 @@ func chunkIndexForOffset(offset int64) (int, error) {
 func writeChunkHeader(w io.Writer, c chunk) error {
 	header := make([]byte, chunkHeaderLen)
 	header[chunkHeaderTypeOffset] = byte(c.encoding())
-	binary.LittleEndian.PutUint64(header[chunkHeaderFirstTimeOffset:], uint64(c.firstTime()))
-	binary.LittleEndian.PutUint64(header[chunkHeaderLastTimeOffset:], uint64(c.lastTime()))
+	binary.LittleEndian.PutUint64(
+		header[chunkHeaderFirstTimeOffset:],
+		uint64(c.firstTime()),
+	)
+	binary.LittleEndian.PutUint64(
+		header[chunkHeaderLastTimeOffset:],
+		uint64(c.newIterator().lastTimestamp()),
+	)
 	_, err := w.Write(header)
 	return err
 }
diff --git a/storage/local/persistence_test.go b/storage/local/persistence_test.go
index 00e36b792..1bf8b24b7 100644
--- a/storage/local/persistence_test.go
+++ b/storage/local/persistence_test.go
@@ -70,8 +70,8 @@ func buildTestChunks(encoding chunkEncoding) map[clientmodel.Fingerprint][]chunk
 }
 
 func chunksEqual(c1, c2 chunk) bool {
-	values2 := c2.values()
-	for v1 := range c1.values() {
+	values2 := c2.newIterator().values()
+	for v1 := range c1.newIterator().values() {
 		v2 := <-values2
 		if !v1.Equal(v2) {
 			return false
@@ -397,7 +397,7 @@ func testCheckpointAndLoadSeriesMapAndHeads(t *testing.T, encoding chunkEncoding
 		if !reflect.DeepEqual(loadedS1.metric, m1) {
 			t.Errorf("want metric %v, got %v", m1, loadedS1.metric)
 		}
-		if !reflect.DeepEqual(loadedS1.head().chunk, s1.head().chunk) {
+		if !reflect.DeepEqual(loadedS1.head().c, s1.head().c) {
 			t.Error("head chunks differ")
 		}
 		if loadedS1.chunkDescsOffset != 0 {
@@ -413,7 +413,7 @@ func testCheckpointAndLoadSeriesMapAndHeads(t *testing.T, encoding chunkEncoding
 		if !reflect.DeepEqual(loadedS3.metric, m3) {
 			t.Errorf("want metric %v, got %v", m3, loadedS3.metric)
 		}
-		if loadedS3.head().chunk != nil {
+		if loadedS3.head().c != nil {
 			t.Error("head chunk not evicted")
 		}
 		if loadedS3.chunkDescsOffset != -1 {
@@ -515,7 +515,7 @@ func TestCheckpointAndLoadFPMappings(t *testing.T) {
 	}
 }
 
-func testGetFingerprintsModifiedBefore(t *testing.T, encoding chunkEncoding) {
+func testFingerprintsModifiedBefore(t *testing.T, encoding chunkEncoding) {
 	p, closer := newTestPersistence(t, encoding)
 	defer closer.Close()
 
@@ -537,7 +537,7 @@ func testGetFingerprintsModifiedBefore(t *testing.T, encoding chunkEncoding) {
 	}
 
 	for ts, want := range expectedFPs {
-		got, err := p.getFingerprintsModifiedBefore(ts)
+		got, err := p.fingerprintsModifiedBefore(ts)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -575,7 +575,7 @@ func testGetFingerprintsModifiedBefore(t *testing.T, encoding chunkEncoding) {
 	}
 
 	for ts, want := range expectedFPs {
-		got, err := p.getFingerprintsModifiedBefore(ts)
+		got, err := p.fingerprintsModifiedBefore(ts)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -585,12 +585,12 @@ func testGetFingerprintsModifiedBefore(t *testing.T, encoding chunkEncoding) {
 	}
 }
 
-func TestGetFingerprintsModifiedBeforeChunkType0(t *testing.T) {
-	testGetFingerprintsModifiedBefore(t, 0)
+func TestFingerprintsModifiedBeforeChunkType0(t *testing.T) {
+	testFingerprintsModifiedBefore(t, 0)
 }
 
-func TestGetFingerprintsModifiedBeforeChunkType1(t *testing.T) {
-	testGetFingerprintsModifiedBefore(t, 1)
+func TestFingerprintsModifiedBeforeChunkType1(t *testing.T) {
+	testFingerprintsModifiedBefore(t, 1)
 }
 
 func testDropArchivedMetric(t *testing.T, encoding chunkEncoding) {
@@ -605,7 +605,7 @@ func testDropArchivedMetric(t *testing.T, encoding chunkEncoding) {
 	p.indexMetric(2, m2)
 	p.waitForIndexing()
 
-	outFPs, err := p.getFingerprintsForLabelPair(metric.LabelPair{Name: "n1", Value: "v1"})
+	outFPs, err := p.fingerprintsForLabelPair(metric.LabelPair{Name: "n1", Value: "v1"})
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -613,7 +613,7 @@ func testDropArchivedMetric(t *testing.T, encoding chunkEncoding) {
 	if !reflect.DeepEqual(outFPs, want) {
 		t.Errorf("want %#v, got %#v", want, outFPs)
 	}
-	outFPs, err = p.getFingerprintsForLabelPair(metric.LabelPair{Name: "n2", Value: "v2"})
+	outFPs, err = p.fingerprintsForLabelPair(metric.LabelPair{Name: "n2", Value: "v2"})
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -637,7 +637,7 @@ func testDropArchivedMetric(t *testing.T, encoding chunkEncoding) {
 	}
 	p.waitForIndexing()
 
-	outFPs, err = p.getFingerprintsForLabelPair(metric.LabelPair{Name: "n1", Value: "v1"})
+	outFPs, err = p.fingerprintsForLabelPair(metric.LabelPair{Name: "n1", Value: "v1"})
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -645,7 +645,7 @@ func testDropArchivedMetric(t *testing.T, encoding chunkEncoding) {
 	if !reflect.DeepEqual(outFPs, want) {
 		t.Errorf("want %#v, got %#v", want, outFPs)
 	}
-	outFPs, err = p.getFingerprintsForLabelPair(metric.LabelPair{Name: "n2", Value: "v2"})
+	outFPs, err = p.fingerprintsForLabelPair(metric.LabelPair{Name: "n2", Value: "v2"})
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -858,7 +858,7 @@ func verifyIndexedState(i int, t *testing.T, b incrementalBatch, indexedFpsToMet
 	p.waitForIndexing()
 	for fp, m := range indexedFpsToMetrics {
 		// Compare archived metrics with input metrics.
-		mOut, err := p.getArchivedMetric(fp)
+		mOut, err := p.archivedMetric(fp)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -884,7 +884,7 @@ func verifyIndexedState(i int, t *testing.T, b incrementalBatch, indexedFpsToMet
 
 	// Compare label name -> label values mappings.
 	for ln, lvs := range b.expectedLnToLvs {
-		outLvs, err := p.getLabelValuesForLabelName(ln)
+		outLvs, err := p.labelValuesForLabelName(ln)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -901,7 +901,7 @@ func verifyIndexedState(i int, t *testing.T, b incrementalBatch, indexedFpsToMet
 
 	// Compare label pair -> fingerprints mappings.
 	for lp, fps := range b.expectedLpToFps {
-		outFPs, err := p.getFingerprintsForLabelPair(lp)
+		outFPs, err := p.fingerprintsForLabelPair(lp)
 		if err != nil {
 			t.Fatal(err)
 		}
diff --git a/storage/local/preload.go b/storage/local/preload.go
index 077cccca0..4bccc0c42 100644
--- a/storage/local/preload.go
+++ b/storage/local/preload.go
@@ -40,8 +40,8 @@ func (p *memorySeriesPreloader) PreloadRange(
 }
 
 /*
-// GetMetricAtTime implements Preloader.
-func (p *memorySeriesPreloader) GetMetricAtTime(fp clientmodel.Fingerprint, t clientmodel.Timestamp) error {
+// MetricAtTime implements Preloader.
+func (p *memorySeriesPreloader) MetricAtTime(fp clientmodel.Fingerprint, t clientmodel.Timestamp) error {
 	cds, err := p.storage.preloadChunks(fp, &timeSelector{
 		from:    t,
 		through: t,
@@ -53,8 +53,8 @@ func (p *memorySeriesPreloader) GetMetricAtTime(fp clientmodel.Fingerprint, t cl
 	return nil
 }
 
-// GetMetricAtInterval implements Preloader.
-func (p *memorySeriesPreloader) GetMetricAtInterval(fp clientmodel.Fingerprint, from, through clientmodel.Timestamp, interval time.Duration) error {
+// MetricAtInterval implements Preloader.
+func (p *memorySeriesPreloader) MetricAtInterval(fp clientmodel.Fingerprint, from, through clientmodel.Timestamp, interval time.Duration) error {
 	cds, err := p.storage.preloadChunks(fp, &timeSelector{
 		from:     from,
 		through:  through,
@@ -67,8 +67,8 @@ func (p *memorySeriesPreloader) GetMetricAtInterval(fp clientmodel.Fingerprint,
 	return
 }
 
-// GetMetricRange implements Preloader.
-func (p *memorySeriesPreloader) GetMetricRange(fp clientmodel.Fingerprint, t clientmodel.Timestamp, rangeDuration time.Duration) error {
+// MetricRange implements Preloader.
+func (p *memorySeriesPreloader) MetricRange(fp clientmodel.Fingerprint, t clientmodel.Timestamp, rangeDuration time.Duration) error {
 	cds, err := p.storage.preloadChunks(fp, &timeSelector{
 		from:          t,
 		through:       t,
@@ -81,8 +81,8 @@ func (p *memorySeriesPreloader) GetMetricRange(fp clientmodel.Fingerprint, t cli
 	return
 }
 
-// GetMetricRangeAtInterval implements Preloader.
-func (p *memorySeriesPreloader) GetMetricRangeAtInterval(fp clientmodel.Fingerprint, from, through clientmodel.Timestamp, interval, rangeDuration time.Duration) error {
+// MetricRangeAtInterval implements Preloader.
+func (p *memorySeriesPreloader) MetricRangeAtInterval(fp clientmodel.Fingerprint, from, through clientmodel.Timestamp, interval, rangeDuration time.Duration) error {
 	cds, err := p.storage.preloadChunks(fp, &timeSelector{
 		from:          from,
 		through:       through,
diff --git a/storage/local/series.go b/storage/local/series.go
index 419ae78bc..60c428441 100644
--- a/storage/local/series.go
+++ b/storage/local/series.go
@@ -208,7 +208,7 @@ func (s *memorySeries) add(v *metric.SamplePair) int {
 		newHead := newChunkDesc(newChunk())
 		s.chunkDescs = append(s.chunkDescs, newHead)
 		s.headChunkClosed = false
-	} else if s.headChunkUsedByIterator && s.head().getRefCount() > 1 {
+	} else if s.headChunkUsedByIterator && s.head().refCount() > 1 {
 		// We only need to clone the head chunk if the current head
 		// chunk was used in an iterator at all and if the refCount is
 		// still greater than the 1 we always have because the head
@@ -221,12 +221,12 @@ func (s *memorySeries) add(v *metric.SamplePair) int {
 		chunkOps.WithLabelValues(clone).Inc()
 		// No locking needed here because a non-persisted head chunk can
 		// not get evicted concurrently.
-		s.head().chunk = s.head().chunk.clone()
+		s.head().c = s.head().c.clone()
 		s.headChunkUsedByIterator = false
 	}
 
 	chunks := s.head().add(v)
-	s.head().chunk = chunks[0]
+	s.head().c = chunks[0]
 
 	for _, c := range chunks[1:] {
 		s.chunkDescs = append(s.chunkDescs, newChunkDesc(c))
@@ -415,10 +415,10 @@ func (s *memorySeries) preloadChunksForRange(
 
 // newIterator returns a new SeriesIterator. The caller must have locked the
 // fingerprint of the memorySeries.
-func (s *memorySeries) newIterator(lockFunc, unlockFunc func()) SeriesIterator {
+func (s *memorySeries) newIterator() SeriesIterator {
 	chunks := make([]chunk, 0, len(s.chunkDescs))
 	for i, cd := range s.chunkDescs {
-		if chunk := cd.getChunk(); chunk != nil {
+		if chunk := cd.chunk(); chunk != nil {
 			if i == len(s.chunkDescs)-1 && !s.headChunkClosed {
 				s.headChunkUsedByIterator = true
 			}
@@ -427,9 +427,8 @@ func (s *memorySeries) newIterator(lockFunc, unlockFunc func()) SeriesIterator {
 	}
 
 	return &memorySeriesIterator{
-		lock:   lockFunc,
-		unlock: unlockFunc,
-		chunks: chunks,
+		chunks:   chunks,
+		chunkIts: make([]chunkIterator, len(chunks)),
 	}
 }
 
@@ -449,13 +448,13 @@ func (s *memorySeries) firstTime() clientmodel.Timestamp {
 	return s.savedFirstTime
 }
 
-// getChunksToPersist returns a slice of chunkDescs eligible for
-// persistence. It's the caller's responsibility to actually persist the
-// returned chunks afterwards. The method sets the persistWatermark and the
-// dirty flag accordingly.
+// chunksToPersist returns a slice of chunkDescs eligible for persistence. It's
+// the caller's responsibility to actually persist the returned chunks
+// afterwards. The method sets the persistWatermark and the dirty flag
+// accordingly.
 //
 // The caller must have locked the fingerprint of the series.
-func (s *memorySeries) getChunksToPersist() []*chunkDesc {
+func (s *memorySeries) chunksToPersist() []*chunkDesc {
 	newWatermark := len(s.chunkDescs)
 	if !s.headChunkClosed {
 		newWatermark--
@@ -471,108 +470,124 @@ func (s *memorySeries) getChunksToPersist() []*chunkDesc {
 
 // memorySeriesIterator implements SeriesIterator.
 type memorySeriesIterator struct {
-	lock, unlock func()
-	chunkIt      chunkIterator
-	chunks       []chunk
+	chunkIt  chunkIterator   // Last chunkIterator used by ValueAtTime.
+	chunkIts []chunkIterator // Caches chunkIterators.
+	chunks   []chunk
 }
 
-// GetValueAtTime implements SeriesIterator.
-func (it *memorySeriesIterator) GetValueAtTime(t clientmodel.Timestamp) metric.Values {
-	it.lock()
-	defer it.unlock()
-
+// ValueAtTime implements SeriesIterator.
+func (it *memorySeriesIterator) ValueAtTime(t clientmodel.Timestamp) metric.Values {
 	// The most common case. We are iterating through a chunk.
 	if it.chunkIt != nil && it.chunkIt.contains(t) {
-		return it.chunkIt.getValueAtTime(t)
+		return it.chunkIt.valueAtTime(t)
 	}
 
-	it.chunkIt = nil
-
 	if len(it.chunks) == 0 {
 		return nil
 	}
 
 	// Before or exactly on the first sample of the series.
-	if !t.After(it.chunks[0].firstTime()) {
+	it.chunkIt = it.chunkIterator(0)
+	ts := it.chunkIt.timestampAtIndex(0)
+	if !t.After(ts) {
 		// return first value of first chunk
-		return it.chunks[0].newIterator().getValueAtTime(t)
-	}
-	// After or exactly on the last sample of the series.
-	if !t.Before(it.chunks[len(it.chunks)-1].lastTime()) {
-		// return last value of last chunk
-		return it.chunks[len(it.chunks)-1].newIterator().getValueAtTime(t)
+		return metric.Values{metric.SamplePair{
+			Timestamp: ts,
+			Value:     it.chunkIt.sampleValueAtIndex(0),
+		}}
 	}
 
-	// Find first chunk where lastTime() is after or equal to t.
+	// After or exactly on the last sample of the series.
+	it.chunkIt = it.chunkIterator(len(it.chunks) - 1)
+	ts = it.chunkIt.lastTimestamp()
+	if !t.Before(ts) {
+		// return last value of last chunk
+		return metric.Values{metric.SamplePair{
+			Timestamp: ts,
+			Value:     it.chunkIt.sampleValueAtIndex(it.chunkIt.length() - 1),
+		}}
+	}
+
+	// Find last chunk where firstTime() is before or equal to t.
+	l := len(it.chunks) - 1
 	i := sort.Search(len(it.chunks), func(i int) bool {
-		return !it.chunks[i].lastTime().Before(t)
+		return !it.chunks[l-i].firstTime().After(t)
 	})
 	if i == len(it.chunks) {
 		panic("out of bounds")
 	}
-
-	if t.Before(it.chunks[i].firstTime()) {
+	it.chunkIt = it.chunkIterator(l - i)
+	ts = it.chunkIt.lastTimestamp()
+	if t.After(ts) {
 		// We ended up between two chunks.
+		sp1 := metric.SamplePair{
+			Timestamp: ts,
+			Value:     it.chunkIt.sampleValueAtIndex(it.chunkIt.length() - 1),
+		}
+		it.chunkIt = it.chunkIterator(l - i + 1)
 		return metric.Values{
-			it.chunks[i-1].newIterator().getValueAtTime(t)[0],
-			it.chunks[i].newIterator().getValueAtTime(t)[0],
+			sp1,
+			metric.SamplePair{
+				Timestamp: it.chunkIt.timestampAtIndex(0),
+				Value:     it.chunkIt.sampleValueAtIndex(0),
+			},
 		}
 	}
-	// We ended up in the middle of a chunk. We might stay there for a while,
-	// so save it as the current chunk iterator.
-	it.chunkIt = it.chunks[i].newIterator()
-	return it.chunkIt.getValueAtTime(t)
+	return it.chunkIt.valueAtTime(t)
 }
 
-// GetBoundaryValues implements SeriesIterator.
-func (it *memorySeriesIterator) GetBoundaryValues(in metric.Interval) metric.Values {
-	it.lock()
-	defer it.unlock()
-
-	// Find the first relevant chunk.
+// BoundaryValues implements SeriesIterator.
+func (it *memorySeriesIterator) BoundaryValues(in metric.Interval) metric.Values {
+	// Find the first chunk for which the first sample is within the interval.
 	i := sort.Search(len(it.chunks), func(i int) bool {
-		return !it.chunks[i].lastTime().Before(in.OldestInclusive)
+		return !it.chunks[i].firstTime().Before(in.OldestInclusive)
 	})
+	// Only now check the last timestamp of the previous chunk (which is
+	// fairly expensive).
+	if i > 0 && !it.chunkIterator(i-1).lastTimestamp().Before(in.OldestInclusive) {
+		i--
+	}
+
 	values := make(metric.Values, 0, 2)
-	for i, c := range it.chunks[i:] {
-		var chunkIt chunkIterator
+	for j, c := range it.chunks[i:] {
 		if c.firstTime().After(in.NewestInclusive) {
 			if len(values) == 1 {
-				// We found the first value before, but are now
+				// We found the first value before but are now
 				// already past the last value. The value we
 				// want must be the last value of the previous
 				// chunk. So backtrack...
-				chunkIt = it.chunks[i-1].newIterator()
-				values = append(values, chunkIt.getValueAtTime(in.NewestInclusive)[0])
+				chunkIt := it.chunkIterator(i + j - 1)
+				values = append(values, metric.SamplePair{
+					Timestamp: chunkIt.lastTimestamp(),
+					Value:     chunkIt.lastSampleValue(),
+				})
 			}
 			break
 		}
+		chunkIt := it.chunkIterator(i + j)
 		if len(values) == 0 {
-			chunkIt = c.newIterator()
-			firstValues := chunkIt.getValueAtTime(in.OldestInclusive)
+			firstValues := chunkIt.valueAtTime(in.OldestInclusive)
 			switch len(firstValues) {
 			case 2:
 				values = append(values, firstValues[1])
 			case 1:
 				values = firstValues
 			default:
-				panic("unexpected return from getValueAtTime")
+				panic("unexpected return from valueAtTime")
 			}
 		}
-		if c.lastTime().After(in.NewestInclusive) {
-			if chunkIt == nil {
-				chunkIt = c.newIterator()
-			}
-			values = append(values, chunkIt.getValueAtTime(in.NewestInclusive)[0])
+		if chunkIt.lastTimestamp().After(in.NewestInclusive) {
+			values = append(values, chunkIt.valueAtTime(in.NewestInclusive)[0])
 			break
 		}
 	}
 	if len(values) == 1 {
 		// We found exactly one value. In that case, add the most recent we know.
-		values = append(
-			values,
-			it.chunks[len(it.chunks)-1].newIterator().getValueAtTime(in.NewestInclusive)[0],
-		)
+		chunkIt := it.chunkIterator(len(it.chunks) - 1)
+		values = append(values, metric.SamplePair{
+			Timestamp: chunkIt.lastTimestamp(),
+			Value:     chunkIt.lastSampleValue(),
+		})
 	}
 	if len(values) == 2 && values[0].Equal(&values[1]) {
 		return values[:1]
@@ -580,41 +595,53 @@ func (it *memorySeriesIterator) GetBoundaryValues(in metric.Interval) metric.Val
 	return values
 }
 
-// GetRangeValues implements SeriesIterator.
-func (it *memorySeriesIterator) GetRangeValues(in metric.Interval) metric.Values {
-	it.lock()
-	defer it.unlock()
-
-	// Find the first relevant chunk.
+// RangeValues implements SeriesIterator.
+func (it *memorySeriesIterator) RangeValues(in metric.Interval) metric.Values {
+	// Find the first chunk for which the first sample is within the interval.
 	i := sort.Search(len(it.chunks), func(i int) bool {
-		return !it.chunks[i].lastTime().Before(in.OldestInclusive)
+		return !it.chunks[i].firstTime().Before(in.OldestInclusive)
 	})
+	// Only now check the last timestamp of the previous chunk (which is
+	// fairly expensive).
+	if i > 0 && !it.chunkIterator(i-1).lastTimestamp().Before(in.OldestInclusive) {
+		i--
+	}
+
 	values := metric.Values{}
-	for _, c := range it.chunks[i:] {
+	for j, c := range it.chunks[i:] {
 		if c.firstTime().After(in.NewestInclusive) {
 			break
 		}
-		// TODO: actually reuse an iterator between calls if we get multiple ranges
-		// from the same chunk.
-		values = append(values, c.newIterator().getRangeValues(in)...)
+		values = append(values, it.chunkIterator(i+j).rangeValues(in)...)
 	}
 	return values
 }
 
+// chunkIterator returns the chunkIterator for the chunk at position i (and
+// creates it if needed).
+func (it *memorySeriesIterator) chunkIterator(i int) chunkIterator {
+	chunkIt := it.chunkIts[i]
+	if chunkIt == nil {
+		chunkIt = it.chunks[i].newIterator()
+		it.chunkIts[i] = chunkIt
+	}
+	return chunkIt
+}
+
 // nopSeriesIterator implements Series Iterator. It never returns any values.
 type nopSeriesIterator struct{}
 
-// GetValueAtTime implements SeriesIterator.
-func (_ nopSeriesIterator) GetValueAtTime(t clientmodel.Timestamp) metric.Values {
+// ValueAtTime implements SeriesIterator.
+func (_ nopSeriesIterator) ValueAtTime(t clientmodel.Timestamp) metric.Values {
 	return metric.Values{}
 }
 
-// GetBoundaryValues implements SeriesIterator.
-func (_ nopSeriesIterator) GetBoundaryValues(in metric.Interval) metric.Values {
+// BoundaryValues implements SeriesIterator.
+func (_ nopSeriesIterator) BoundaryValues(in metric.Interval) metric.Values {
 	return metric.Values{}
 }
 
-// GetRangeValues implements SeriesIterator.
-func (_ nopSeriesIterator) GetRangeValues(in metric.Interval) metric.Values {
+// RangeValues implements SeriesIterator.
+func (_ nopSeriesIterator) RangeValues(in metric.Interval) metric.Values {
 	return metric.Values{}
 }
diff --git a/storage/local/storage.go b/storage/local/storage.go
index a57f2e84e..e4fda7789 100644
--- a/storage/local/storage.go
+++ b/storage/local/storage.go
@@ -278,10 +278,7 @@ func (s *memorySeriesStorage) NewIterator(fp clientmodel.Fingerprint) SeriesIter
 		// return any values.
 		return nopSeriesIterator{}
 	}
-	return series.newIterator(
-		func() { s.fpLocker.Lock(fp) },
-		func() { s.fpLocker.Unlock(fp) },
-	)
+	return series.newIterator()
 }
 
 // NewPreloader implements Storage.
@@ -291,14 +288,14 @@ func (s *memorySeriesStorage) NewPreloader() Preloader {
 	}
 }
 
-// GetFingerprintsForLabelMatchers implements Storage.
-func (s *memorySeriesStorage) GetFingerprintsForLabelMatchers(labelMatchers metric.LabelMatchers) clientmodel.Fingerprints {
+// FingerprintsForLabelMatchers implements Storage.
+func (s *memorySeriesStorage) FingerprintsForLabelMatchers(labelMatchers metric.LabelMatchers) clientmodel.Fingerprints {
 	var result map[clientmodel.Fingerprint]struct{}
 	for _, matcher := range labelMatchers {
 		intersection := map[clientmodel.Fingerprint]struct{}{}
 		switch matcher.Type {
 		case metric.Equal:
-			fps, err := s.persistence.getFingerprintsForLabelPair(
+			fps, err := s.persistence.fingerprintsForLabelPair(
 				metric.LabelPair{
 					Name:  matcher.Name,
 					Value: matcher.Value,
@@ -316,7 +313,7 @@ func (s *memorySeriesStorage) GetFingerprintsForLabelMatchers(labelMatchers metr
 				}
 			}
 		default:
-			values, err := s.persistence.getLabelValuesForLabelName(matcher.Name)
+			values, err := s.persistence.labelValuesForLabelName(matcher.Name)
 			if err != nil {
 				log.Errorf("Error getting label values for label name %q: %v", matcher.Name, err)
 			}
@@ -325,7 +322,7 @@ func (s *memorySeriesStorage) GetFingerprintsForLabelMatchers(labelMatchers metr
 				return nil
 			}
 			for _, v := range matches {
-				fps, err := s.persistence.getFingerprintsForLabelPair(
+				fps, err := s.persistence.fingerprintsForLabelPair(
 					metric.LabelPair{
 						Name:  matcher.Name,
 						Value: v,
@@ -354,17 +351,17 @@ func (s *memorySeriesStorage) GetFingerprintsForLabelMatchers(labelMatchers metr
 	return fps
 }
 
-// GetLabelValuesForLabelName implements Storage.
-func (s *memorySeriesStorage) GetLabelValuesForLabelName(labelName clientmodel.LabelName) clientmodel.LabelValues {
-	lvs, err := s.persistence.getLabelValuesForLabelName(labelName)
+// LabelValuesForLabelName implements Storage.
+func (s *memorySeriesStorage) LabelValuesForLabelName(labelName clientmodel.LabelName) clientmodel.LabelValues {
+	lvs, err := s.persistence.labelValuesForLabelName(labelName)
 	if err != nil {
 		log.Errorf("Error getting label values for label name %q: %v", labelName, err)
 	}
 	return lvs
 }
 
-// GetMetricForFingerprint implements Storage.
-func (s *memorySeriesStorage) GetMetricForFingerprint(fp clientmodel.Fingerprint) clientmodel.COWMetric {
+// MetricForFingerprint implements Storage.
+func (s *memorySeriesStorage) MetricForFingerprint(fp clientmodel.Fingerprint) clientmodel.COWMetric {
 	s.fpLocker.Lock(fp)
 	defer s.fpLocker.Unlock(fp)
 
@@ -376,7 +373,7 @@ func (s *memorySeriesStorage) GetMetricForFingerprint(fp clientmodel.Fingerprint
 			Metric: series.metric,
 		}
 	}
-	metric, err := s.persistence.getArchivedMetric(fp)
+	metric, err := s.persistence.archivedMetric(fp)
 	if err != nil {
 		log.Errorf("Error retrieving archived metric for fingerprint %v: %v", fp, err)
 	}
@@ -459,7 +456,7 @@ func (s *memorySeriesStorage) preloadChunksForRange(
 			return nil, nil
 		}
 		if from.Add(-stalenessDelta).Before(last) && through.Add(stalenessDelta).After(first) {
-			metric, err := s.persistence.getArchivedMetric(fp)
+			metric, err := s.persistence.archivedMetric(fp)
 			if err != nil {
 				return nil, err
 			}
@@ -648,7 +645,7 @@ func (s *memorySeriesStorage) cycleThroughArchivedFingerprints() chan clientmode
 		defer close(archivedFingerprints)
 
 		for {
-			archivedFPs, err := s.persistence.getFingerprintsModifiedBefore(
+			archivedFPs, err := s.persistence.fingerprintsModifiedBefore(
 				clientmodel.TimestampFromTime(time.Now()).Add(-s.dropAfter),
 			)
 			if err != nil {
@@ -844,20 +841,21 @@ func (s *memorySeriesStorage) maintainMemorySeries(
 func (s *memorySeriesStorage) writeMemorySeries(
 	fp clientmodel.Fingerprint, series *memorySeries, beforeTime clientmodel.Timestamp,
 ) bool {
-	cds := series.getChunksToPersist()
+	cds := series.chunksToPersist()
 	defer func() {
 		for _, cd := range cds {
 			cd.unpin(s.evictRequests)
 		}
 		s.incNumChunksToPersist(-len(cds))
 		chunkOps.WithLabelValues(persistAndUnpin).Add(float64(len(cds)))
-		series.modTime = s.persistence.getSeriesFileModTime(fp)
+		series.modTime = s.persistence.seriesFileModTime(fp)
 	}()
 
 	// Get the actual chunks from underneath the chunkDescs.
+	// No lock required as chunks still to persist cannot be evicted.
 	chunks := make([]chunk, len(cds))
 	for i, cd := range cds {
-		chunks[i] = cd.chunk
+		chunks[i] = cd.c
 	}
 
 	if !series.firstTime().Before(beforeTime) {
diff --git a/storage/local/storage_test.go b/storage/local/storage_test.go
index 479133915..8b43ae2a1 100644
--- a/storage/local/storage_test.go
+++ b/storage/local/storage_test.go
@@ -28,7 +28,7 @@ import (
 	"github.com/prometheus/prometheus/utility/test"
 )
 
-func TestGetFingerprintsForLabelMatchers(t *testing.T) {
+func TestFingerprintsForLabelMatchers(t *testing.T) {
 	storage, closer := NewTestStorage(t, 1)
 	defer closer.Close()
 
@@ -121,7 +121,7 @@ func TestGetFingerprintsForLabelMatchers(t *testing.T) {
 	}
 
 	for _, mt := range matcherTests {
-		resfps := storage.GetFingerprintsForLabelMatchers(mt.matchers)
+		resfps := storage.FingerprintsForLabelMatchers(mt.matchers)
 		if len(mt.expected) != len(resfps) {
 			t.Fatalf("expected %d matches for %q, found %d", len(mt.expected), mt.matchers, len(resfps))
 		}
@@ -208,7 +208,7 @@ func testChunk(t *testing.T, encoding chunkEncoding) {
 			if cd.isEvicted() {
 				continue
 			}
-			for sample := range cd.chunk.values() {
+			for sample := range cd.c.newIterator().values() {
 				values = append(values, *sample)
 			}
 		}
@@ -234,8 +234,8 @@ func TestChunkType1(t *testing.T) {
 	testChunk(t, 1)
 }
 
-func testGetValueAtTime(t *testing.T, encoding chunkEncoding) {
-	samples := make(clientmodel.Samples, 1000)
+func testValueAtTime(t *testing.T, encoding chunkEncoding) {
+	samples := make(clientmodel.Samples, 10000)
 	for i := range samples {
 		samples[i] = &clientmodel.Sample{
 			Timestamp: clientmodel.Timestamp(2 * i),
@@ -256,7 +256,7 @@ func testGetValueAtTime(t *testing.T, encoding chunkEncoding) {
 
 	// #1 Exactly on a sample.
 	for i, expected := range samples {
-		actual := it.GetValueAtTime(expected.Timestamp)
+		actual := it.ValueAtTime(expected.Timestamp)
 
 		if len(actual) != 1 {
 			t.Fatalf("1.%d. Expected exactly one result, got %d.", i, len(actual))
@@ -275,7 +275,7 @@ func testGetValueAtTime(t *testing.T, encoding chunkEncoding) {
 			continue
 		}
 		expected2 := samples[i+1]
-		actual := it.GetValueAtTime(expected1.Timestamp + 1)
+		actual := it.ValueAtTime(expected1.Timestamp + 1)
 
 		if len(actual) != 2 {
 			t.Fatalf("2.%d. Expected exactly 2 results, got %d.", i, len(actual))
@@ -296,7 +296,7 @@ func testGetValueAtTime(t *testing.T, encoding chunkEncoding) {
 
 	// #3 Corner cases: Just before the first sample, just after the last.
 	expected := samples[0]
-	actual := it.GetValueAtTime(expected.Timestamp - 1)
+	actual := it.ValueAtTime(expected.Timestamp - 1)
 	if len(actual) != 1 {
 		t.Fatalf("3.1. Expected exactly one result, got %d.", len(actual))
 	}
@@ -307,7 +307,7 @@ func testGetValueAtTime(t *testing.T, encoding chunkEncoding) {
 		t.Errorf("3.1. Got %v; want %v", actual[0].Value, expected.Value)
 	}
 	expected = samples[len(samples)-1]
-	actual = it.GetValueAtTime(expected.Timestamp + 1)
+	actual = it.ValueAtTime(expected.Timestamp + 1)
 	if len(actual) != 1 {
 		t.Fatalf("3.2. Expected exactly one result, got %d.", len(actual))
 	}
@@ -319,16 +319,89 @@ func testGetValueAtTime(t *testing.T, encoding chunkEncoding) {
 	}
 }
 
-func TestGetValueAtTimeChunkType0(t *testing.T) {
-	testGetValueAtTime(t, 0)
+func TestValueAtTimeChunkType0(t *testing.T) {
+	testValueAtTime(t, 0)
 }
 
-func TestGetValueAtTimeChunkType1(t *testing.T) {
-	testGetValueAtTime(t, 1)
+func TestValueAtTimeChunkType1(t *testing.T) {
+	testValueAtTime(t, 1)
 }
 
-func testGetRangeValues(t *testing.T, encoding chunkEncoding) {
-	samples := make(clientmodel.Samples, 1000)
+func benchmarkValueAtTime(b *testing.B, encoding chunkEncoding) {
+	samples := make(clientmodel.Samples, 10000)
+	for i := range samples {
+		samples[i] = &clientmodel.Sample{
+			Timestamp: clientmodel.Timestamp(2 * i),
+			Value:     clientmodel.SampleValue(float64(i) * 0.2),
+		}
+	}
+	s, closer := NewTestStorage(b, encoding)
+	defer closer.Close()
+
+	for _, sample := range samples {
+		s.Append(sample)
+	}
+	s.WaitForIndexing()
+
+	fp := clientmodel.Metric{}.FastFingerprint()
+
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		it := s.NewIterator(fp)
+
+		// #1 Exactly on a sample.
+		for i, expected := range samples {
+			actual := it.ValueAtTime(expected.Timestamp)
+
+			if len(actual) != 1 {
+				b.Fatalf("1.%d. Expected exactly one result, got %d.", i, len(actual))
+			}
+			if expected.Timestamp != actual[0].Timestamp {
+				b.Errorf("1.%d. Got %v; want %v", i, actual[0].Timestamp, expected.Timestamp)
+			}
+			if expected.Value != actual[0].Value {
+				b.Errorf("1.%d. Got %v; want %v", i, actual[0].Value, expected.Value)
+			}
+		}
+
+		// #2 Between samples.
+		for i, expected1 := range samples {
+			if i == len(samples)-1 {
+				continue
+			}
+			expected2 := samples[i+1]
+			actual := it.ValueAtTime(expected1.Timestamp + 1)
+
+			if len(actual) != 2 {
+				b.Fatalf("2.%d. Expected exactly 2 results, got %d.", i, len(actual))
+			}
+			if expected1.Timestamp != actual[0].Timestamp {
+				b.Errorf("2.%d. Got %v; want %v", i, actual[0].Timestamp, expected1.Timestamp)
+			}
+			if expected1.Value != actual[0].Value {
+				b.Errorf("2.%d. Got %v; want %v", i, actual[0].Value, expected1.Value)
+			}
+			if expected2.Timestamp != actual[1].Timestamp {
+				b.Errorf("2.%d. Got %v; want %v", i, actual[1].Timestamp, expected1.Timestamp)
+			}
+			if expected2.Value != actual[1].Value {
+				b.Errorf("2.%d. Got %v; want %v", i, actual[1].Value, expected1.Value)
+			}
+		}
+	}
+}
+
+func BenchmarkValueAtTimeChunkType0(b *testing.B) {
+	benchmarkValueAtTime(b, 0)
+}
+
+func BenchmarkValueAtTimeChunkType1(b *testing.B) {
+	benchmarkValueAtTime(b, 1)
+}
+
+func testRangeValues(t *testing.T, encoding chunkEncoding) {
+	samples := make(clientmodel.Samples, 10000)
 	for i := range samples {
 		samples[i] = &clientmodel.Sample{
 			Timestamp: clientmodel.Timestamp(2 * i),
@@ -349,7 +422,7 @@ func testGetRangeValues(t *testing.T, encoding chunkEncoding) {
 
 	// #1 Zero length interval at sample.
 	for i, expected := range samples {
-		actual := it.GetRangeValues(metric.Interval{
+		actual := it.RangeValues(metric.Interval{
 			OldestInclusive: expected.Timestamp,
 			NewestInclusive: expected.Timestamp,
 		})
@@ -367,7 +440,7 @@ func testGetRangeValues(t *testing.T, encoding chunkEncoding) {
 
 	// #2 Zero length interval off sample.
 	for i, expected := range samples {
-		actual := it.GetRangeValues(metric.Interval{
+		actual := it.RangeValues(metric.Interval{
 			OldestInclusive: expected.Timestamp + 1,
 			NewestInclusive: expected.Timestamp + 1,
 		})
@@ -379,7 +452,7 @@ func testGetRangeValues(t *testing.T, encoding chunkEncoding) {
 
 	// #3 2sec interval around sample.
 	for i, expected := range samples {
-		actual := it.GetRangeValues(metric.Interval{
+		actual := it.RangeValues(metric.Interval{
 			OldestInclusive: expected.Timestamp - 1,
 			NewestInclusive: expected.Timestamp + 1,
 		})
@@ -401,7 +474,7 @@ func testGetRangeValues(t *testing.T, encoding chunkEncoding) {
 			continue
 		}
 		expected2 := samples[i+1]
-		actual := it.GetRangeValues(metric.Interval{
+		actual := it.RangeValues(metric.Interval{
 			OldestInclusive: expected1.Timestamp,
 			NewestInclusive: expected1.Timestamp + 2,
 		})
@@ -426,7 +499,7 @@ func testGetRangeValues(t *testing.T, encoding chunkEncoding) {
 	// #5 corner cases: Interval ends at first sample, interval starts
 	// at last sample, interval entirely before/after samples.
 	expected := samples[0]
-	actual := it.GetRangeValues(metric.Interval{
+	actual := it.RangeValues(metric.Interval{
 		OldestInclusive: expected.Timestamp - 2,
 		NewestInclusive: expected.Timestamp,
 	})
@@ -440,7 +513,7 @@ func testGetRangeValues(t *testing.T, encoding chunkEncoding) {
 		t.Errorf("5.1. Got %v; want %v.", actual[0].Value, expected.Value)
 	}
 	expected = samples[len(samples)-1]
-	actual = it.GetRangeValues(metric.Interval{
+	actual = it.RangeValues(metric.Interval{
 		OldestInclusive: expected.Timestamp,
 		NewestInclusive: expected.Timestamp + 2,
 	})
@@ -454,7 +527,7 @@ func testGetRangeValues(t *testing.T, encoding chunkEncoding) {
 		t.Errorf("5.2. Got %v; want %v.", actual[0].Value, expected.Value)
 	}
 	firstSample := samples[0]
-	actual = it.GetRangeValues(metric.Interval{
+	actual = it.RangeValues(metric.Interval{
 		OldestInclusive: firstSample.Timestamp - 4,
 		NewestInclusive: firstSample.Timestamp - 2,
 	})
@@ -462,7 +535,7 @@ func testGetRangeValues(t *testing.T, encoding chunkEncoding) {
 		t.Fatalf("5.3. Expected no results, got %d.", len(actual))
 	}
 	lastSample := samples[len(samples)-1]
-	actual = it.GetRangeValues(metric.Interval{
+	actual = it.RangeValues(metric.Interval{
 		OldestInclusive: lastSample.Timestamp + 2,
 		NewestInclusive: lastSample.Timestamp + 4,
 	})
@@ -471,16 +544,61 @@ func testGetRangeValues(t *testing.T, encoding chunkEncoding) {
 	}
 }
 
-func TestGetRangeValuesChunkType0(t *testing.T) {
-	testGetRangeValues(t, 0)
+func TestRangeValuesChunkType0(t *testing.T) {
+	testRangeValues(t, 0)
 }
 
-func TestGetRangeValuesChunkType1(t *testing.T) {
-	testGetRangeValues(t, 1)
+func TestRangeValuesChunkType1(t *testing.T) {
+	testRangeValues(t, 1)
+}
+
+func benchmarkRangeValues(b *testing.B, encoding chunkEncoding) {
+	samples := make(clientmodel.Samples, 10000)
+	for i := range samples {
+		samples[i] = &clientmodel.Sample{
+			Timestamp: clientmodel.Timestamp(2 * i),
+			Value:     clientmodel.SampleValue(float64(i) * 0.2),
+		}
+	}
+	s, closer := NewTestStorage(b, encoding)
+	defer closer.Close()
+
+	for _, sample := range samples {
+		s.Append(sample)
+	}
+	s.WaitForIndexing()
+
+	fp := clientmodel.Metric{}.FastFingerprint()
+
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+
+		it := s.NewIterator(fp)
+
+		for _, sample := range samples {
+			actual := it.RangeValues(metric.Interval{
+				OldestInclusive: sample.Timestamp - 20,
+				NewestInclusive: sample.Timestamp + 20,
+			})
+
+			if len(actual) < 10 {
+				b.Fatalf("not enough samples found")
+			}
+		}
+	}
+}
+
+func BenchmarkRangeValuesChunkType0(b *testing.B) {
+	benchmarkRangeValues(b, 0)
+}
+
+func BenchmarkRangeValuesChunkType1(b *testing.B) {
+	benchmarkRangeValues(b, 1)
 }
 
 func testEvictAndPurgeSeries(t *testing.T, encoding chunkEncoding) {
-	samples := make(clientmodel.Samples, 1000)
+	samples := make(clientmodel.Samples, 10000)
 	for i := range samples {
 		samples[i] = &clientmodel.Sample{
 			Timestamp: clientmodel.Timestamp(2 * i),
@@ -498,29 +616,29 @@ func testEvictAndPurgeSeries(t *testing.T, encoding chunkEncoding) {
 	fp := clientmodel.Metric{}.FastFingerprint()
 
 	// Drop ~half of the chunks.
-	s.maintainMemorySeries(fp, 1000)
+	s.maintainMemorySeries(fp, 10000)
 	it := s.NewIterator(fp)
-	actual := it.GetBoundaryValues(metric.Interval{
+	actual := it.BoundaryValues(metric.Interval{
 		OldestInclusive: 0,
-		NewestInclusive: 10000,
+		NewestInclusive: 100000,
 	})
 	if len(actual) != 2 {
 		t.Fatal("expected two results after purging half of series")
 	}
-	if actual[0].Timestamp < 600 || actual[0].Timestamp > 1000 {
+	if actual[0].Timestamp < 6000 || actual[0].Timestamp > 10000 {
 		t.Errorf("1st timestamp out of expected range: %v", actual[0].Timestamp)
 	}
-	want := clientmodel.Timestamp(1998)
+	want := clientmodel.Timestamp(19998)
 	if actual[1].Timestamp != want {
 		t.Errorf("2nd timestamp: want %v, got %v", want, actual[1].Timestamp)
 	}
 
 	// Drop everything.
-	s.maintainMemorySeries(fp, 10000)
+	s.maintainMemorySeries(fp, 100000)
 	it = s.NewIterator(fp)
-	actual = it.GetBoundaryValues(metric.Interval{
+	actual = it.BoundaryValues(metric.Interval{
 		OldestInclusive: 0,
-		NewestInclusive: 10000,
+		NewestInclusive: 100000,
 	})
 	if len(actual) != 0 {
 		t.Fatal("expected zero results after purging the whole series")
@@ -558,7 +676,7 @@ func testEvictAndPurgeSeries(t *testing.T, encoding chunkEncoding) {
 	}
 
 	// Drop ~half of the chunks of an archived series.
-	s.maintainArchivedSeries(fp, 1000)
+	s.maintainArchivedSeries(fp, 10000)
 	archived, _, _, err = s.persistence.hasArchivedMetric(fp)
 	if err != nil {
 		t.Fatal(err)
@@ -568,7 +686,7 @@ func testEvictAndPurgeSeries(t *testing.T, encoding chunkEncoding) {
 	}
 
 	// Drop everything.
-	s.maintainArchivedSeries(fp, 10000)
+	s.maintainArchivedSeries(fp, 100000)
 	archived, _, _, err = s.persistence.hasArchivedMetric(fp)
 	if err != nil {
 		t.Fatal(err)
@@ -625,7 +743,7 @@ func testEvictAndPurgeSeries(t *testing.T, encoding chunkEncoding) {
 
 	// This will archive again, but must not drop it completely, despite the
 	// memorySeries being empty.
-	s.maintainMemorySeries(fp, 1000)
+	s.maintainMemorySeries(fp, 10000)
 	archived, _, _, err = s.persistence.hasArchivedMetric(fp)
 	if err != nil {
 		t.Fatal(err)
@@ -685,7 +803,7 @@ func testFuzz(t *testing.T, encoding chunkEncoding) {
 		s, c := NewTestStorage(t, encoding)
 		defer c.Close()
 
-		samples := createRandomSamples("test_fuzz", 1000)
+		samples := createRandomSamples("test_fuzz", 10000)
 		for _, sample := range samples {
 			s.Append(sample)
 		}
@@ -917,7 +1035,7 @@ func verifyStorage(t testing.TB, s *memorySeriesStorage, samples clientmodel.Sam
 		}
 		p := s.NewPreloader()
 		p.PreloadRange(fp, sample.Timestamp, sample.Timestamp, time.Hour)
-		found := s.NewIterator(fp).GetValueAtTime(sample.Timestamp)
+		found := s.NewIterator(fp).ValueAtTime(sample.Timestamp)
 		if len(found) != 1 {
 			t.Errorf("Sample %#v: Expected exactly one value, found %d.", sample, len(found))
 			result = false
diff --git a/web/api/query.go b/web/api/query.go
index d606898b4..52da47f8b 100644
--- a/web/api/query.go
+++ b/web/api/query.go
@@ -156,7 +156,7 @@ func (serv MetricsService) Metrics(w http.ResponseWriter, r *http.Request) {
 	setAccessControlHeaders(w)
 	w.Header().Set("Content-Type", "application/json")
 
-	metricNames := serv.Storage.GetLabelValuesForLabelName(clientmodel.MetricNameLabel)
+	metricNames := serv.Storage.LabelValuesForLabelName(clientmodel.MetricNameLabel)
 	sort.Sort(metricNames)
 	resultBytes, err := json.Marshal(metricNames)
 	if err != nil {