diff --git a/tsdb/engine/tsm1/bool.go b/tsdb/engine/tsm1/bool.go
index 3cac8a09ef..3ad1cbd961 100644
--- a/tsdb/engine/tsm1/bool.go
+++ b/tsdb/engine/tsm1/bool.go
@@ -10,14 +10,9 @@ import (
 	"fmt"
 )
 
-const (
-	// booleanUncompressed is an uncompressed boolean format.
-	// Not yet implemented.
-	booleanUncompressed = 0
-
-	// booleanCompressedBitPacked is an bit packed format using 1 bit per boolean
-	booleanCompressedBitPacked = 1
-)
+// Note: an uncompressed boolean format is not yet implemented.
+// booleanCompressedBitPacked is a bit packed format using 1 bit per boolean
+const booleanCompressedBitPacked = 1
 
 // BooleanEncoder encodes a series of booleans to an in-memory buffer.
 type BooleanEncoder struct {
diff --git a/tsdb/engine/tsm1/cache.go b/tsdb/engine/tsm1/cache.go
index 6506796afa..c49406eca4 100644
--- a/tsdb/engine/tsm1/cache.go
+++ b/tsdb/engine/tsm1/cache.go
@@ -514,15 +514,6 @@ func (c *Cache) Split(n int) []*Cache {
 	return caches
 }
 
-// unsortedKeys returns a slice of all keys under management by the cache. The
-// keys are not sorted.
-func (c *Cache) unsortedKeys() [][]byte {
-	c.mu.RLock()
-	store := c.store
-	c.mu.RUnlock()
-	return store.keys(false)
-}
-
 // Values returns a copy of all values, deduped and sorted, for the given key.
 func (c *Cache) Values(key []byte) Values {
 	var snapshotEntries *entry
diff --git a/tsdb/engine/tsm1/cache_test.go b/tsdb/engine/tsm1/cache_test.go
index 309b428972..33bf87249a 100644
--- a/tsdb/engine/tsm1/cache_test.go
+++ b/tsdb/engine/tsm1/cache_test.go
@@ -443,7 +443,7 @@ func TestCache_CacheSnapshot(t *testing.T) {
 	}
 
 	// Create another snapshot
-	snapshot, err = c.Snapshot()
+	_, err = c.Snapshot()
 	if err != nil {
 		t.Fatalf("failed to snapshot cache: %v", err)
 	}
@@ -454,7 +454,7 @@ func TestCache_CacheSnapshot(t *testing.T) {
 
 	c.ClearSnapshot(true)
 
-	snapshot, err = c.Snapshot()
+	_, err = c.Snapshot()
 	if err != nil {
 		t.Fatalf("failed to snapshot cache: %v", err)
 	}
diff --git a/tsdb/engine/tsm1/digest.go b/tsdb/engine/tsm1/digest.go
index 7b3d9142a7..3c98e8e023 100644
--- a/tsdb/engine/tsm1/digest.go
+++ b/tsdb/engine/tsm1/digest.go
@@ -122,15 +122,3 @@ func Digest(dir string, w io.WriteCloser) error {
 		MaxTime: math.MaxInt64,
 	}, w)
 }
-
-type rwPair struct {
-	r    *TSMReader
-	w    TSMWriter
-	outf *os.File
-}
-
-func (rw *rwPair) close() {
-	rw.r.Close()
-	rw.w.Close()
-	rw.outf.Close()
-}
diff --git a/tsdb/engine/tsm1/engine.go b/tsdb/engine/tsm1/engine.go
index 020dca3523..86835ee200 100644
--- a/tsdb/engine/tsm1/engine.go
+++ b/tsdb/engine/tsm1/engine.go
@@ -1233,7 +1233,6 @@ func (e *Engine) DeleteSeriesRange(itr tsdb.SeriesIterator, min, max int64) erro
 		if err := e.deleteSeriesRange(batch, min, max); err != nil {
 			return err
 		}
-		batch = batch[:0]
 	}
 
 	e.index.Rebuild()
@@ -2771,40 +2770,6 @@ func SeriesAndFieldFromCompositeKey(key []byte) ([]byte, []byte) {
 	return key[:sep], key[sep+len(keyFieldSeparator):]
 }
 
-// readDir recursively reads all files from a path.
-func readDir(root, rel string) ([]string, error) {
-	// Open root.
-	f, err := os.Open(filepath.Join(root, rel))
-	if err != nil {
-		return nil, err
-	}
-	defer f.Close()
-
-	// Read all files.
-	fis, err := f.Readdir(-1)
-	if err != nil {
-		return nil, err
-	}
-
-	// Read all subdirectories and append to the end.
-	var paths []string
-	for _, fi := range fis {
-		// Simply append if it's a file.
-		if !fi.IsDir() {
-			paths = append(paths, filepath.Join(rel, fi.Name()))
-			continue
-		}
-
-		// Read and append nested file paths.
-		children, err := readDir(root, filepath.Join(rel, fi.Name()))
-		if err != nil {
-			return nil, err
-		}
-		paths = append(paths, children...)
-	}
-	return paths, nil
-}
-
 func varRefSliceContains(a []influxql.VarRef, v string) bool {
 	for _, ref := range a {
 		if ref.Val == v {
diff --git a/tsdb/engine/tsm1/file_store.go b/tsdb/engine/tsm1/file_store.go
index 4db738c295..52795fcd4d 100644
--- a/tsdb/engine/tsm1/file_store.go
+++ b/tsdb/engine/tsm1/file_store.go
@@ -815,37 +815,6 @@ func (f *FileStore) BlockCount(path string, idx int) int {
 	return 0
 }
 
-// walkFiles calls fn for each file in filestore in parallel.
-func (f *FileStore) walkFiles(fn func(f TSMFile) error) error {
-	// Copy the current TSM files to prevent a slow walker from
-	// blocking other operations.
-	f.mu.RLock()
-	files := make([]TSMFile, len(f.files))
-	copy(files, f.files)
-	f.mu.RUnlock()
-
-	// struct to hold the result of opening each reader in a goroutine
-	errC := make(chan error, len(files))
-	for _, f := range files {
-		go func(tsm TSMFile) {
-			if err := fn(tsm); err != nil {
-				errC <- fmt.Errorf("file %s: %s", tsm.Path(), err)
-				return
-			}
-
-			errC <- nil
-		}(f)
-	}
-
-	for i := 0; i < cap(errC); i++ {
-		res := <-errC
-		if res != nil {
-			return res
-		}
-	}
-	return nil
-}
-
 // We need to determine the possible files that may be accessed by this query given
 // the time range.
 func (f *FileStore) cost(key []byte, min, max int64) query.IteratorCost {
@@ -1125,23 +1094,6 @@ func (c *KeyCursor) Close() {
 	c.current = nil
 }
 
-// hasOverlappingBlocks returns true if blocks have overlapping time ranges.
-// This result is computed once and stored as the "duplicates" field.
-func (c *KeyCursor) hasOverlappingBlocks() bool {
-	if len(c.seeks) == 0 {
-		return false
-	}
-
-	for i := 1; i < len(c.seeks); i++ {
-		prev := c.seeks[i-1]
-		cur := c.seeks[i]
-		if prev.entry.MaxTime >= cur.entry.MinTime {
-			return true
-		}
-	}
-	return false
-}
-
 // seek positions the cursor at the given time.
 func (c *KeyCursor) seek(t int64) {
 	if len(c.seeks) == 0 {
@@ -1353,11 +1305,6 @@ func (a tsmReaders) Len() int           { return len(a) }
 func (a tsmReaders) Less(i, j int) bool { return a[i].Path() < a[j].Path() }
 func (a tsmReaders) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
 
-type stream struct {
-	c chan seriesKey
-	v seriesKey
-}
-
 type seriesKey struct {
 	key []byte
 	typ byte
diff --git a/tsdb/engine/tsm1/float.go b/tsdb/engine/tsm1/float.go
index b088e1653a..0abf24e7dc 100644
--- a/tsdb/engine/tsm1/float.go
+++ b/tsdb/engine/tsm1/float.go
@@ -18,14 +18,9 @@ import (
 	"github.com/influxdata/influxdb/pkg/bits"
 )
 
-const (
-	// floatUncompressed is an uncompressed format using 8 bytes per value.
-	// Not yet implemented.
-	floatUncompressed = 0
-
-	// floatCompressedGorilla is a compressed format using the gorilla paper encoding
-	floatCompressedGorilla = 1
-)
+// Note: an uncompressed format is not yet implemented.
+// floatCompressedGorilla is a compressed format using the gorilla paper encoding
+const floatCompressedGorilla = 1
 
 // uvnan is the constant returned from math.NaN().
 const uvnan = 0x7FF8000000000001
diff --git a/tsdb/engine/tsm1/string.go b/tsdb/engine/tsm1/string.go
index ccc4f407cb..fe6b5e9b20 100644
--- a/tsdb/engine/tsm1/string.go
+++ b/tsdb/engine/tsm1/string.go
@@ -12,14 +12,10 @@ import (
 	"github.com/golang/snappy"
 )
 
-const (
-	// stringUncompressed is a an uncompressed format encoding strings as raw bytes.
-	// Not yet implemented.
-	stringUncompressed = 0
+// Note: an uncompressed format is not yet implemented.
 
-	// stringCompressedSnappy is a compressed encoding using Snappy compression
-	stringCompressedSnappy = 1
-)
+// stringCompressedSnappy is a compressed encoding using Snappy compression
+const stringCompressedSnappy = 1
 
 // StringEncoder encodes multiple strings into a byte slice.
 type StringEncoder struct {
diff --git a/tsdb/engine/tsm1/tombstone.go b/tsdb/engine/tsm1/tombstone.go
index 3fee1709f4..a8b99444a6 100644
--- a/tsdb/engine/tsm1/tombstone.go
+++ b/tsdb/engine/tsm1/tombstone.go
@@ -341,24 +341,6 @@ func (t *Tombstoner) prepareV4() error {
 	return nil
 }
 
-// writeTombstoneV4 writes v3 files that are concatenated together.  A v4 header is
-// written to indicated this is a v4 file.
-func (t *Tombstoner) writeTombstoneV4(tombstones []Tombstone) error {
-	if err := t.prepareV4(); err == errIncompatibleVersion {
-		return t.writeTombstoneV3(tombstones)
-	} else if err != nil {
-		return err
-	}
-
-	for _, ts := range tombstones {
-		if err := t.writeTombstone(t.gz, ts); err != nil {
-			return err
-		}
-	}
-
-	return t.commit()
-}
-
 func (t *Tombstoner) commit() error {
 	// No pending writes
 	if t.pendingFile == nil {
diff --git a/tsdb/engine/tsm1/writer.go b/tsdb/engine/tsm1/writer.go
index a82f22079e..00c4d8c249 100644
--- a/tsdb/engine/tsm1/writer.go
+++ b/tsdb/engine/tsm1/writer.go
@@ -246,12 +246,6 @@ func NewDiskIndexWriter(f *os.File) IndexWriter {
 	return &directIndex{fd: f, w: bufio.NewWriterSize(f, 1024*1024)}
 }
 
-// indexBlock represent an index information for a series within a TSM file.
-type indexBlock struct {
-	key     []byte
-	entries *indexEntries
-}
-
 type syncer interface {
 	Name() string
 	Sync() error