diff --git a/command.go b/command.go
index ff722c7..0dc7481 100644
--- a/command.go
+++ b/command.go
@@ -60,8 +60,8 @@ func equalCommand(str, lowerText string) bool {
 		return false
 	}
 	const s = 'a' - 'A'
-	for i, lo := range lowerText {
-		delta := lo - rune(str[i])
+	for i, lt := range lowerText {
+		delta := lt - rune(str[i])
 		if delta != 0 && delta != s {
 			return false
 		}
diff --git a/command_test.go b/command_test.go
index 9c84c96..1db5cc3 100644
--- a/command_test.go
+++ b/command_test.go
@@ -97,10 +97,8 @@ func TestCommand(t *testing.T) {
 		assert.Equal(resm, map[string]string{"k1": "v1", "k2": "v2", "k3": "v3", "k4": "v4", "k5": "v5"})
 
 		// hdel
-		{
-			res, _ := rdb.HDel(ctx, "map", "k1", "k2", "k3", "k99").Result()
-			assert.Equal(res, int64(3))
-		}
+		res, _ = rdb.HDel(ctx, "map", "k1", "k2", "k3", "k99").Result()
+		assert.Equal(res, int64(3))
 
 		// error
 		_, err := rdb.HSet(ctx, "map").Result()
@@ -123,6 +121,9 @@ func TestCommand(t *testing.T) {
 		res, _ := rdb.LRange(ctx, "list", 0, -1).Result()
 		assert.Equal(res, []string{"c", "b", "a", "d", "e", "f"})
 
+		res, _ = rdb.LRange(ctx, "list", 1, 3).Result()
+		assert.Equal(res, []string{"b", "a"})
+
 		// lpop
 		val, _ := rdb.LPop(ctx, "list").Result()
 		assert.Equal(val, "c")
diff --git a/internal/list/bench_test.go b/internal/list/bench_test.go
index 68e388c..03f10fc 100644
--- a/internal/list/bench_test.go
+++ b/internal/list/bench_test.go
@@ -31,20 +31,34 @@ func BenchmarkList(b *testing.B) {
 			ls.RPop()
 		}
 	})
-	b.Run("range", func(b *testing.B) {
+	b.Run("range_all", func(b *testing.B) {
 		ls := genList(0, 1000)
 		b.ResetTimer()
 		for i := 0; i < b.N; i++ {
 			ls.Range(0, -1, func([]byte) {})
 		}
 	})
-	b.Run("revrange", func(b *testing.B) {
+	b.Run("range_100", func(b *testing.B) {
+		ls := genList(0, 1000)
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			ls.Range(0, 100, func([]byte) {})
+		}
+	})
+	b.Run("revrange_all", func(b *testing.B) {
 		ls := genList(0, 1000)
 		b.ResetTimer()
 		for i := 0; i < b.N; i++ {
 			ls.RevRange(0, -1, func([]byte) {})
 		}
 	})
+	b.Run("revrange_100", func(b *testing.B) {
+		ls := genList(0, 1000)
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			ls.RevRange(0, 100, func([]byte) {})
+		}
+	})
 }
 
 func BenchmarkListPack(b *testing.B) {
diff --git a/internal/list/list.go b/internal/list/list.go
index 2891d7a..7dbead5 100644
--- a/internal/list/list.go
+++ b/internal/list/list.go
@@ -18,10 +18,6 @@ type Node struct {
 	prev, next *Node
 }
 
-func SetMaxListPackSize(s int) {
-	maxListPackSize = s
-}
-
 // New create a quicklist instance.
 func New() *QuickList {
 	n := newNode()
@@ -97,11 +93,28 @@ func (ls *QuickList) Range(start, end int, f func(data []byte)) {
 	if end == -1 {
 		end = math.MaxInt
 	}
-	for lp := ls.head; lp != nil; lp = lp.next {
-		it := lp.Iterator().SeekBegin()
-		for !it.IsEnd() {
-			f(it.Next())
+	count := end - start
+
+	lp := ls.head
+	for lp != nil && start > lp.Size() {
+		start -= lp.Size()
+		lp = lp.next
+	}
+
+	it := lp.Iterator().SeekBegin()
+	for range start {
+		it.Next()
+	}
+
+	for range count {
+		if it.IsEnd() {
+			if lp.next == nil {
+				return
+			}
+			lp = lp.next
+			it = lp.Iterator().SeekBegin()
 		}
+		f(it.Next())
 	}
 }
 
@@ -109,10 +122,27 @@ func (ls *QuickList) RevRange(start, end int, f func(data []byte)) {
 	if end == -1 {
 		end = math.MaxInt
 	}
-	for lp := ls.tail; lp != nil; lp = lp.prev {
-		it := lp.Iterator().SeekEnd()
-		for !it.IsBegin() {
-			f(it.Prev())
+	count := end - start
+
+	lp := ls.tail
+	for lp != nil && start > lp.Size() {
+		start -= lp.Size()
+		lp = lp.prev
+	}
+
+	it := lp.Iterator().SeekEnd()
+	for range start {
+		it.Prev()
+	}
+
+	for range count {
+		if it.IsBegin() {
+			if lp.prev == nil {
+				return
+			}
+			lp = lp.prev
+			it = lp.Iterator().SeekEnd()
 		}
+		f(it.Prev())
 	}
 }
diff --git a/internal/list/list_test.go b/internal/list/list_test.go
index 17e1d56..34ffebd 100644
--- a/internal/list/list_test.go
+++ b/internal/list/list_test.go
@@ -23,9 +23,8 @@ func list2slice(ls *QuickList) (res []string) {
 }
 
 func TestList(t *testing.T) {
-	const N = 1000
+	const N = 10000
 	assert := assert.New(t)
-	SetMaxListPackSize(128)
 
 	t.Run("lpush", func(t *testing.T) {
 		ls := New()
@@ -87,6 +86,15 @@ func TestList(t *testing.T) {
 			i++
 		})
 		assert.Equal(i, N)
+
+		for _, start := range []int{100, 1000, 5000} {
+			i = 0
+			ls.Range(start, start+100, func(data []byte) {
+				assert.Equal(string(data), genKey(start+i))
+				i++
+			})
+			assert.Equal(i, 100)
+		}
 	})
 
 	t.Run("revrange", func(t *testing.T) {
@@ -97,5 +105,14 @@ func TestList(t *testing.T) {
 			i++
 		})
 		assert.Equal(i, N)
+
+		for _, start := range []int{100, 1000, 5000} {
+			i = 0
+			ls.RevRange(start, start+100, func(data []byte) {
+				assert.Equal(string(data), genKey(N-start-i-1))
+				i++
+			})
+			assert.Equal(i, 100)
+		}
 	})
 }
diff --git a/internal/list/listpack.go b/internal/list/listpack.go
index 440fd24..674f70a 100644
--- a/internal/list/listpack.go
+++ b/internal/list/listpack.go
@@ -8,11 +8,12 @@ import (
 	"github.com/xgzlucario/rotom/internal/pkg"
 )
 
-var (
+const (
 	maxListPackSize = 8 * 1024
+)
 
-	bpool = pkg.NewBufferPool()
-
+var (
+	bpool      = pkg.NewBufferPool()
 	encoder, _ = zstd.NewWriter(nil)
 	decoder, _ = zstd.NewReader(nil)
 )
diff --git a/internal/sstring/sstring.go b/internal/sstring/sstring.go
deleted file mode 100644
index ccc0b31..0000000
--- a/internal/sstring/sstring.go
+++ /dev/null
@@ -1,38 +0,0 @@
-// package sstring is shared strings.
-
-package sstring
-
-import (
-	"strings"
-
-	"github.com/cockroachdb/swiss"
-)
-
-var nums = swiss.New[string, int](8)
-var strs []string
-
-// Load a shared string from its number.
-func Load(num int) (str string) {
-	if num >= 0 && num < len(strs) {
-		str = strs[num]
-		return str
-	}
-	panic("string not found")
-}
-
-// Store a shared string.
-func Store(str string) int {
-	num, ok := nums.Get(str)
-	if !ok {
-		str = strings.Clone(str)
-		num = len(strs)
-		strs = append(strs, str)
-		nums.Put(str, num)
-	}
-	return num
-}
-
-// Len returns the number of shared strings.
-func Len() int {
-	return len(strs)
-}
diff --git a/internal/sstring/sstring_test.go b/internal/sstring/sstring_test.go
deleted file mode 100644
index aa742b1..0000000
--- a/internal/sstring/sstring_test.go
+++ /dev/null
@@ -1,77 +0,0 @@
-package sstring
-
-import (
-	"crypto/rand"
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-)
-
-func TestShared(t *testing.T) {
-	assert := assert.New(t)
-
-	for i := -1; i < 10; i++ {
-		var str string
-		func() {
-			defer func() {
-				assert.True(recover().(string) == "string not found")
-			}()
-			str = Load(i)
-		}()
-		assert.Equal(str, "")
-	}
-	assert.Equal(Store("hello"), 0)
-	assert.Equal(Store(""), 1)
-	assert.Equal(Store("jello"), 2)
-	assert.Equal(Store("hello"), 0)
-	assert.Equal(Store(""), 1)
-	assert.Equal(Store("jello"), 2)
-	assert.Equal(Load(0), "hello")
-	assert.Equal(Load(1), "")
-	assert.Equal(Load(2), "jello")
-	assert.Equal(Len(), 3)
-
-}
-
-func randStr(n int) string {
-	b := make([]byte, n)
-	rand.Read(b)
-	for i := 0; i < n; i++ {
-		b[i] = 'a' + b[i]%26
-	}
-	return string(b)
-}
-
-func BenchmarkStore(b *testing.B) {
-	wmap := make(map[string]bool, b.N)
-	for len(wmap) < b.N {
-		wmap[randStr(10)] = true
-	}
-	words := make([]string, 0, b.N)
-	for word := range wmap {
-		words = append(words, word)
-	}
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		Store(words[i])
-	}
-}
-
-func BenchmarkLoad(b *testing.B) {
-	wmap := make(map[string]bool, b.N)
-	for len(wmap) < b.N {
-		wmap[randStr(10)] = true
-	}
-	words := make([]string, 0, b.N)
-	for word := range wmap {
-		words = append(words, word)
-	}
-	var nums []int
-	for i := 0; i < b.N; i++ {
-		nums = append(nums, Store(words[i]))
-	}
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		Load(nums[i])
-	}
-}
diff --git a/rotom.go b/rotom.go
index 3c51018..2fa7b80 100644
--- a/rotom.go
+++ b/rotom.go
@@ -155,7 +155,7 @@ func ProcessQueryBuf(client *Client) {
 		} else {
 			err := ErrUnknownCommand(command)
 			client.replyWriter.WriteError(err)
-			log.Warn().Msgf("ERR %v", err)
+			log.Error().Msg(err.Error())
 		}
 	}
 
@@ -197,12 +197,8 @@ func initServer(config *Config) (err error) {
 }
 
 func SyncAOF(loop *AeLoop, id int, extra interface{}) {
-	if db.aof == nil {
-		return
-	}
-	err := db.aof.Flush()
-	if err != nil {
-		log.Error().Msgf("flush aof buffer error: %v", err)
+	if err := db.aof.Flush(); err != nil {
+		log.Error().Msgf("sync aof error: %v", err)
 	}
 }