diff --git a/tsdb/block_test.go b/tsdb/block_test.go
index 0f83ac5c0..ef19468a3 100644
--- a/tsdb/block_test.go
+++ b/tsdb/block_test.go
@@ -267,16 +267,20 @@ func TestBlockSize(t *testing.T) {
 }
 
 func TestReadIndexFormatV1(t *testing.T) {
-	/* The block here was produced at commit
-	   07ef80820ef1250db82f9544f3fcf7f0f63ccee0 with:
-	db, _ := Open("v1db", nil, nil, nil)
-	app := db.Appender()
-	app.Add(labels.FromStrings("foo", "bar"), 1, 2)
-	app.Add(labels.FromStrings("foo", "baz"), 3, 4)
-	app.Add(labels.FromStrings("foo", "meh"), 1000*3600*4, 4) // Not in the block.
-	app.Commit()
-	db.compact()
-	db.Close()
+	/* The block here was produced at the commit
+	    706602daed1487f7849990678b4ece4599745905 used in 2.0.0 with:
+	   db, _ := Open("v1db", nil, nil, nil)
+	   app := db.Appender()
+	   app.Add(labels.FromStrings("foo", "bar"), 1, 2)
+	   app.Add(labels.FromStrings("foo", "baz"), 3, 4)
+	   app.Add(labels.FromStrings("foo", "meh"), 1000*3600*4, 4) // Not in the block.
+	   // Make sure we've enough values for the lack of sorting of postings offsets to show up.
+	   for i := 0; i < 100; i++ {
+	     app.Add(labels.FromStrings("bar", strconv.FormatInt(int64(i), 10)), 0, 0)
+	   }
+	   app.Commit()
+	   db.compact()
+	   db.Close()
 	*/
 
 	blockDir := filepath.Join("testdata", "index_format_v1")
@@ -290,7 +294,7 @@ func TestReadIndexFormatV1(t *testing.T) {
 
 	q, err = NewBlockQuerier(block, 0, 1000)
 	testutil.Ok(t, err)
-	testutil.Equals(t, query(t, q, labels.MustNewMatcher(labels.MatchNotRegexp, "foo", "^.$")),
+	testutil.Equals(t, query(t, q, labels.MustNewMatcher(labels.MatchNotRegexp, "foo", "^.?$")),
 		map[string][]tsdbutil.Sample{
 			`{foo="bar"}`: []tsdbutil.Sample{sample{t: 1, v: 2}},
 			`{foo="baz"}`: []tsdbutil.Sample{sample{t: 3, v: 4}},
diff --git a/tsdb/index/index.go b/tsdb/index/index.go
index 18fa0360e..dd1a0dd37 100644
--- a/tsdb/index/index.go
+++ b/tsdb/index/index.go
@@ -1024,6 +1024,8 @@ type Reader struct {
 	// Map of LabelName to a list of some LabelValues's position in the offset table.
 	// The first and last values for each name are always present.
 	postings map[string][]postingOffset
+	// For the v1 format, labelname -> labelvalue -> offset.
+	postingsV1 map[string]map[string]uint64
 
 	symbols     *Symbols
 	nameSymbols map[uint32]string // Cache of the label name symbol lookups,
@@ -1113,45 +1115,64 @@ func newReader(b ByteSlice, c io.Closer) (*Reader, error) {
 		return nil, errors.Wrap(err, "read symbols")
 	}
 
-	var lastKey []string
-	lastOff := 0
-	valueCount := 0
-	// For the postings offset table we keep every label name but only every nth
-	// label value (plus the first and last one), to save memory.
-	if err := ReadOffsetTable(r.b, r.toc.PostingsTable, func(key []string, _ uint64, off int) error {
-		if len(key) != 2 {
-			return errors.Errorf("unexpected key length for posting table %d", len(key))
-		}
-		if _, ok := r.postings[key[0]]; !ok {
-			// Next label name.
-			r.postings[key[0]] = []postingOffset{}
-			if lastKey != nil {
-				// Always include last value for each label name.
-				r.postings[lastKey[0]] = append(r.postings[lastKey[0]], postingOffset{value: lastKey[1], off: lastOff})
+	if r.version == FormatV1 {
+		// Earlier V1 formats don't have a sorted postings offset table, so
+		// load the whole offset table into memory.
+		r.postingsV1 = map[string]map[string]uint64{}
+		if err := ReadOffsetTable(r.b, r.toc.PostingsTable, func(key []string, off uint64, _ int) error {
+			if len(key) != 2 {
+				return errors.Errorf("unexpected key length for posting table %d", len(key))
 			}
-			lastKey = nil
-			valueCount = 0
+			if _, ok := r.postingsV1[key[0]]; !ok {
+				r.postingsV1[key[0]] = map[string]uint64{}
+				r.postings[key[0]] = nil // Used to get a list of labelnames in places.
+			}
+			r.postingsV1[key[0]][key[1]] = off
+			return nil
+		}); err != nil {
+			return nil, errors.Wrap(err, "read postings table")
 		}
-		if valueCount%32 == 0 {
-			r.postings[key[0]] = append(r.postings[key[0]], postingOffset{value: key[1], off: off})
-			lastKey = nil
-		} else {
-			lastKey = key
-			lastOff = off
+	} else {
+		var lastKey []string
+		lastOff := 0
+		valueCount := 0
+		// For the postings offset table we keep every label name but only every nth
+		// label value (plus the first and last one), to save memory.
+		if err := ReadOffsetTable(r.b, r.toc.PostingsTable, func(key []string, _ uint64, off int) error {
+			if len(key) != 2 {
+				return errors.Errorf("unexpected key length for posting table %d", len(key))
+			}
+			if _, ok := r.postings[key[0]]; !ok {
+				// Next label name.
+				r.postings[key[0]] = []postingOffset{}
+				if lastKey != nil {
+					// Always include last value for each label name.
+					r.postings[lastKey[0]] = append(r.postings[lastKey[0]], postingOffset{value: lastKey[1], off: lastOff})
+				}
+				lastKey = nil
+				valueCount = 0
+			}
+			if valueCount%32 == 0 {
+				r.postings[key[0]] = append(r.postings[key[0]], postingOffset{value: key[1], off: off})
+				lastKey = nil
+			} else {
+				lastKey = key
+				lastOff = off
+			}
+			valueCount++
+			return nil
+		}); err != nil {
+			return nil, errors.Wrap(err, "read postings table")
+		}
+		if lastKey != nil {
+			r.postings[lastKey[0]] = append(r.postings[lastKey[0]], postingOffset{value: lastKey[1], off: lastOff})
+		}
+		// Trim any extra space in the slices.
+		for k, v := range r.postings {
+			l := make([]postingOffset, len(v))
+			copy(l, v)
+			r.postings[k] = l
 		}
-		valueCount++
-		return nil
-	}); err != nil {
-		return nil, errors.Wrap(err, "read postings table")
-	}
-	if lastKey != nil {
-		r.postings[lastKey[0]] = append(r.postings[lastKey[0]], postingOffset{value: lastKey[1], off: lastOff})
-	}
-	// Trim any extra space in the slices.
-	for k, v := range r.postings {
-		l := make([]postingOffset, len(v))
-		copy(l, v)
-		r.postings[k] = l
 	}
 
 	r.nameSymbols = make(map[uint32]string, len(r.postings))
@@ -1408,6 +1429,19 @@ func (r *Reader) LabelValues(names ...string) (StringTuples, error) {
 	if len(names) != 1 {
 		return nil, errors.Errorf("only one label name supported")
 	}
+	if r.version == FormatV1 {
+		e, ok := r.postingsV1[names[0]]
+		if !ok {
+			return emptyStringTuples{}, nil
+		}
+		values := make([]string, 0, len(e))
+		for k := range e {
+			values = append(values, k)
+		}
+		sort.Strings(values)
+		return NewStringTuples(values, 1)
+
+	}
 	e, ok := r.postings[names[0]]
 	if !ok {
 		return emptyStringTuples{}, nil
@@ -1467,6 +1501,28 @@ func (r *Reader) Series(id uint64, lbls *labels.Labels, chks *[]chunks.Meta) err
 }
 
 func (r *Reader) Postings(name string, values ...string) (Postings, error) {
+	if r.version == FormatV1 {
+		e, ok := r.postingsV1[name]
+		if !ok {
+			return EmptyPostings(), nil
+		}
+		res := make([]Postings, 0, len(values))
+		for _, v := range values {
+			postingsOff, ok := e[v]
+			if !ok {
+				continue
+			}
+			// Read from the postings table.
+			d := encoding.NewDecbufAt(r.b, int(postingsOff), castagnoliTable)
+			_, p, err := r.dec.Postings(d.Get())
+			if err != nil {
+				return nil, errors.Wrap(err, "decode postings")
+			}
+			res = append(res, p)
+		}
+		return Merge(res...), nil
+	}
+
 	e, ok := r.postings[name]
 	if !ok {
 		return EmptyPostings(), nil
diff --git a/tsdb/testdata/index_format_v1/chunks/000001 b/tsdb/testdata/index_format_v1/chunks/000001
index 1f2250b86..ac544dbbe 100644
Binary files a/tsdb/testdata/index_format_v1/chunks/000001 and b/tsdb/testdata/index_format_v1/chunks/000001 differ
diff --git a/tsdb/testdata/index_format_v1/index b/tsdb/testdata/index_format_v1/index
index 8804430fb..76b0a3092 100644
Binary files a/tsdb/testdata/index_format_v1/index and b/tsdb/testdata/index_format_v1/index differ
diff --git a/tsdb/testdata/index_format_v1/meta.json b/tsdb/testdata/index_format_v1/meta.json
index 62347db26..d99ae6b49 100644
--- a/tsdb/testdata/index_format_v1/meta.json
+++ b/tsdb/testdata/index_format_v1/meta.json
@@ -1,17 +1,17 @@
 {
 	"version": 1,
-	"ulid": "01DVZX4CHY2EGZ6JQVS80AB9CF",
+	"ulid": "01DXXFZDYD1MQW6079WK0K6EDQ",
 	"minTime": 0,
 	"maxTime": 7200000,
 	"stats": {
-		"numSamples": 2,
-		"numSeries": 2,
-		"numChunks": 2
+		"numSamples": 102,
+		"numSeries": 102,
+		"numChunks": 102
 	},
 	"compaction": {
 		"level": 1,
 		"sources": [
-			"01DVZX4CHY2EGZ6JQVS80AB9CF"
+			"01DXXFZDYD1MQW6079WK0K6EDQ"
 		]
 	}
 }