diff --git a/ledis/scan.go b/ledis/scan.go
new file mode 100644
index 0000000..a1f5fe2
--- /dev/null
+++ b/ledis/scan.go
@@ -0,0 +1,86 @@
+package ledis
+
+import (
+	"errors"
+	"github.com/siddontang/ledisdb/store"
+)
+
+var errDataType = errors.New("error data type")
+var errMetaKey = errors.New("error meta key")
+
+func (db *DB) scan(dataType byte, key []byte, count int, inclusive bool) ([][]byte, error) {
+	var minKey, maxKey []byte
+	var err error
+	if key != nil {
+		if err = db.checkKeySize(key); err != nil {
+			return nil, err
+		}
+		if minKey, err = db.encodeOffsetKey(dataType, key); err != nil {
+			return nil, err
+		}
+
+	} else {
+		if minKey, err = db.encodeMinKey(dataType); err != nil {
+			return nil, err
+		}
+	}
+
+	if maxKey, err = db.encodeMaxKey(dataType); err != nil {
+		return nil, err
+	}
+
+	if count <= 0 {
+		count = defaultScanCount
+	}
+
+	v := make([][]byte, 0, count)
+
+	rangeType := store.RangeROpen
+	if !inclusive {
+		rangeType = store.RangeOpen
+	}
+
+	it := db.db.RangeLimitIterator(minKey, maxKey, rangeType, 0, count)
+	for ; it.Valid(); it.Next() {
+		if k, err := db.decodeMetaKey(dataType, it.Key()); err != nil {
+			continue
+		} else {
+			v = append(v, k)
+		}
+	}
+	it.Close()
+	return v, nil
+}
+
+func (db *DB) encodeMinKey(dataType byte) ([]byte, error) {
+	return db.encodeOffsetKey(dataType, nil)
+}
+
+func (db *DB) encodeMaxKey(dataType byte) ([]byte, error) {
+	k := db.encodeOffsetKey(dataType, nil)
+	k[len(k)-1] = dataType + 1
+	return k, nil
+}
+
+func (db *DB) encodeMetaKey(dataType byte, key []byte) ([]byte, error) {
+	switch dataType {
+	case KVType:
+		return db.encodeKVKey(key), nil
+	case LMetaType:
+		return db.lEncodeMetaKey(key), nil
+	case HSizeType:
+		return db.hEncodeSizeKey(key), nil
+	case ZSizeType:
+		return db.zEncodeSizeKey(key), nil
+	case BitMetaType:
+		return db.bEncodeMetaKey(key), nil
+	default:
+		return nil, errInvalidDataType
+	}
+}
+func (db *DB) decodeMetaKey(dataType, byte, ek []byte) ([]byte, error) {
+	if len(ek) < 2 || ek[0] != db.index || ek[1] != dataType {
+		return nil, errMetaKey
+	}
+	return ek[2:], nil
+}
diff --git a/ledis/scan_test.go b/ledis/scan_test.go
new file mode 100644
index 0000000..86ac846
--- /dev/null
+++ b/ledis/scan_test.go
@@ -0,0 +1,83 @@
+package ledis
+
+import (
+	"testing"
+)
+
+func TestDBScan(t *testing.T) {
+	db := getTestDB()
+
+	db.FlushAll()
+
+	if v, err := db.Scan(nil, 10, true); err != nil {
+		t.Fatal(err)
+	} else if len(v) != 0 {
+		t.Fatal(len(v))
+	}
+
+	db.Set([]byte("a"), []byte{})
+	db.Set([]byte("b"), []byte{})
+	db.Set([]byte("c"), []byte{})
+
+	if v, err := db.Scan(nil, 1, true); err != nil {
+		t.Fatal(err)
+	} else if len(v) != 1 {
+		t.Fatal(len(v))
+	}
+
+	if v, err := db.Scan([]byte("a"), 2, false); err != nil {
+		t.Fatal(err)
+	} else if len(v) != 2 {
+		t.Fatal(len(v))
+	}
+
+	if v, err := db.Scan(nil, 3, true); err != nil {
+		t.Fatal(err)
+	} else if len(v) != 3 {
+		t.Fatal(len(v))
+	}
+}
+
+func TestDBHScan(t *testing.T) {
+	db := getTestDB()
+
+	db.hFlush()
+
+	k1 := []byte("k1")
+	db.HSet(k1, []byte("1"), []byte{})
+
+	k2 := []byte("k2")
+	db.HSet(k2, []byte("2"), []byte{})
+
+	k3 := []byte("k3")
+	db.HSet(k3, []byte("3"), []byte{})
+
+	if v, err := db.HScan(nil, 1, true); err != nil {
+		t.Fatal(err)
+	} else if len(v) != 1 {
+		t.Fatal("invalid length ", len(v))
+	} else if string(v[0]) != "k1" {
+		t.Fatal("invalid value ", string(v[0]))
+	}
+
+	if v, err := db.HScan(k1, 2, true); err != nil {
+		t.Fatal(err)
+	} else if len(v) != 2 {
+		t.Fatal("invalid length ", len(v))
+	} else if string(v[0]) != "k1" {
+		t.Fatal("invalid value ", string(v[0]))
+	} else if string(v[1]) != "k2" {
+		t.Fatal("invalid value ", string(v[1]))
+	}
+
+	if v, err := db.HScan(k1, 2, false); err != nil {
+		t.Fatal(err)
+	} else if len(v) != 2 {
+		t.Fatal("invalid length ", len(v))
+	} else if string(v[0]) != "k2" {
+		t.Fatal("invalid value ", string(v[0]))
+	} else if string(v[1]) != "k3" {
+		t.Fatal("invalid value ", string(v[1]))
+	}
+
+}
diff --git a/ledis/t_hash.go b/ledis/t_hash.go
index 41c8ccb..eb6bbb1 100644
--- a/ledis/t_hash.go
+++ b/ledis/t_hash.go
@@ -472,48 +472,8 @@ func (db *DB) hFlush() (drop int64, err error) {
 	return
 }
 
-func (db *DB) hEncodeMinKey() []byte {
-	return db.hEncodeSizeKey(nil)
-}
-
-func (db *DB) hEncodeMaxKey() []byte {
-	ek := db.hEncodeSizeKey(nil)
-	ek[len(ek)-1] = HSizeType + 1
-	return ek
-}
-
 func (db *DB) HScan(key []byte, count int, inclusive bool) ([][]byte, error) {
-	var minKey []byte
-	if key != nil {
-		minKey = db.hEncodeSizeKey(key)
-
-	} else {
-		minKey = db.hEncodeMinKey()
-	}
-
-	maxKey := db.hEncodeMaxKey()
-
-	if count <= 0 {
-		count = defaultScanCount
-	}
-
-	v := make([][]byte, 0, count)
-
-	rangeType := store.RangeROpen
-	if !inclusive {
-		rangeType = store.RangeOpen
-	}
-
-	it := db.db.RangeLimitIterator(minKey, maxKey, rangeType, 0, count)
-	for ; it.Valid(); it.Next() {
-		if k, err := db.hDecodeSizeKey(it.Key()); err != nil {
-			continue
-		} else {
-			v = append(v, k)
-		}
-	}
-	it.Close()
-	return v, nil
+	return db.scan(HSizeType, key, count, inclusive)
 }
 
 func (db *DB) HExpire(key []byte, duration int64) (int64, error) {
diff --git a/ledis/t_hash_test.go b/ledis/t_hash_test.go
index ff8e6a0..bf7cc7c 100644
--- a/ledis/t_hash_test.go
+++ b/ledis/t_hash_test.go
@@ -56,50 +56,6 @@ func TestDBHash(t *testing.T) {
 
 }
 
-func TestDBHScan(t *testing.T) {
-	db := getTestDB()
-
-	db.hFlush()
-
-	k1 := []byte("k1")
-	db.HSet(k1, []byte("1"), []byte{})
-
-	k2 := []byte("k2")
-	db.HSet(k2, []byte("2"), []byte{})
-
-	k3 := []byte("k3")
-	db.HSet(k3, []byte("3"), []byte{})
-
-	if v, err := db.HScan(nil, 1, true); err != nil {
-		t.Fatal(err)
-	} else if len(v) != 1 {
-		t.Fatal("invalid length ", len(v))
-	} else if string(v[0]) != "k1" {
-		t.Fatal("invalid value ", string(v[0]))
-	}
-
-	if v, err := db.HScan(k1, 2, true); err != nil {
-		t.Fatal(err)
-	} else if len(v) != 2 {
-		t.Fatal("invalid length ", len(v))
-	} else if string(v[0]) != "k1" {
-		t.Fatal("invalid value ", string(v[0]))
-	} else if string(v[1]) != "k2" {
-		t.Fatal("invalid value ", string(v[1]))
-	}
-
-	if v, err := db.HScan(k1, 2, false); err != nil {
-		t.Fatal(err)
-	} else if len(v) != 2 {
-		t.Fatal("invalid length ", len(v))
-	} else if string(v[0]) != "k2" {
-		t.Fatal("invalid value ", string(v[0]))
-	} else if string(v[1]) != "k3" {
-		t.Fatal("invalid value ", string(v[1]))
-	}
-
-}
-
 func TestHashPersist(t *testing.T) {
 	db := getTestDB()
 
diff --git a/ledis/t_kv.go b/ledis/t_kv.go
index f11f525..b58a678 100644
--- a/ledis/t_kv.go
+++ b/ledis/t_kv.go
@@ -324,41 +324,8 @@ func (db *DB) flush() (drop int64, err error) {
 }
 
 //if inclusive is true, scan range [key, inf) else (key, inf)
-func (db *DB) Scan(key []byte, count int, inclusive bool) ([]KVPair, error) {
-	var minKey []byte
-	if key != nil {
-		if err := checkKeySize(key); err != nil {
-			return nil, err
-		}
-		minKey = db.encodeKVKey(key)
-	} else {
-		minKey = db.encodeKVMinKey()
-	}
-
-	maxKey := db.encodeKVMaxKey()
-
-	if count <= 0 {
-		count = defaultScanCount
-	}
-
-	v := make([]KVPair, 0, 2*count)
-
-	rangeType := store.RangeROpen
-	if !inclusive {
-		rangeType = store.RangeOpen
-	}
-
-	it := db.db.RangeLimitIterator(minKey, maxKey, rangeType, 0, count)
-	for ; it.Valid(); it.Next() {
-		if key, err := db.decodeKVKey(it.Key()); err != nil {
-			continue
-		} else {
-			v = append(v, KVPair{Key: key, Value: it.Value()})
-		}
-	}
-	it.Close()
-
-	return v, nil
+func (db *DB) Scan(key []byte, count int, inclusive bool) ([][]byte, error) {
+	return db.scan(KVType, key, count, inclusive)
 }
 
 func (db *DB) Expire(key []byte, duration int64) (int64, error) {
diff --git a/ledis/t_kv_test.go b/ledis/t_kv_test.go
index 680aa5b..714e104 100644
--- a/ledis/t_kv_test.go
+++ b/ledis/t_kv_test.go
@@ -43,40 +43,6 @@ func TestDBKV(t *testing.T) {
 
 }
 
-func TestDBScan(t *testing.T) {
-	db := getTestDB()
-
-	db.FlushAll()
-
-	if v, err := db.Scan(nil, 10, true); err != nil {
-		t.Fatal(err)
-	} else if len(v) != 0 {
-		t.Fatal(len(v))
-	}
-
-	db.Set([]byte("a"), []byte{})
-	db.Set([]byte("b"), []byte{})
-	db.Set([]byte("c"), []byte{})
-
-	if v, err := db.Scan(nil, 1, true); err != nil {
-		t.Fatal(err)
-	} else if len(v) != 1 {
-		t.Fatal(len(v))
-	}
-
-	if v, err := db.Scan([]byte("a"), 2, false); err != nil {
-		t.Fatal(err)
-	} else if len(v) != 2 {
-		t.Fatal(len(v))
-	}
-
-	if v, err := db.Scan(nil, 3, true); err != nil {
-		t.Fatal(err)
-	} else if len(v) != 3 {
-		t.Fatal(len(v))
-	}
-}
-
 func TestKVPersist(t *testing.T) {
 	db := getTestDB()
 
diff --git a/ledis/t_list.go b/ledis/t_list.go
index 079498e..f851013 100644
--- a/ledis/t_list.go
+++ b/ledis/t_list.go
@@ -484,3 +484,17 @@ func (db *DB) LPersist(key []byte) (int64, error) {
 	err = t.Commit()
 	return n, err
 }
+
+func (db *DB) LScan(key []byte, count int, inclusive bool) ([][]byte, error) {
+	return db.scan(LMetaType, key, count, inclusive)
+}
+
+func (db *DB) lEncodeMinKey() []byte {
+	return db.lEncodeMetaKey(nil)
+}
+
+func (db *DB) lEncodeMaxKey() []byte {
+	ek := db.lEncodeMetaKey(nil)
+	ek[len(ek)-1] = LMetaType + 1
+	return ek
+}
diff --git a/ledis/t_zset.go b/ledis/t_zset.go
index 964361e..f039487 100644
--- a/ledis/t_zset.go
+++ b/ledis/t_zset.go
@@ -1004,3 +1004,7 @@ func (db *DB) ZInterStore(destKey []byte, srcKeys [][]byte, weights []int64, agg
 	}
 	return int64(len(keptMembers)), nil
 }
+
+func (db *DB) ZScan(key []byte, count int, inclusive bool) ([][]byte, error) {
+	return db.scan(ZSizeType, key, count, inclusive)
+}
diff --git a/server/client_http.go b/server/client_http.go
index 16f3b9a..01272d5 100644
--- a/server/client_http.go
+++ b/server/client_http.go
@@ -1,17 +1,16 @@
 package server
 
 import (
+	"encoding/json"
 	"fmt"
+	"github.com/siddontang/go-bson/bson"
 	"github.com/siddontang/go-log/log"
 	"github.com/siddontang/ledisdb/ledis"
+	"github.com/ugorji/go/codec"
 	"io"
 	"net/http"
 	"strconv"
 	"strings"
-
-	"encoding/json"
-	"github.com/siddontang/go-bson/bson"
-	"github.com/ugorji/go/codec"
 )
 
 var allowedContentTypes = map[string]struct{}{