diff --git a/kv/kv.go b/kv/kv.go
index 0e3f52c08b..481d9653bb 100644
--- a/kv/kv.go
+++ b/kv/kv.go
@@ -61,20 +61,20 @@ type Version struct {
 }
 
 var (
-	// MaxVersion is the maximum version, notice that it's not a valid version
+	// MaxVersion is the maximum version, notice that it's not a valid version.
 	MaxVersion = Version{Ver: math.MaxUint64}
 	// MinVersion is the minimum version, it's not a valid version, too.
 	MinVersion = Version{Ver: 0}
 )
 
-// NewVersion is a simple wrapper.
+// NewVersion creates a new Version struct.
 func NewVersion(v uint64) Version {
 	return Version{
 		Ver: v,
 	}
 }
 
-// Cmp returns the comparison result of two version.
+// Cmp returns the comparison result of two versions.
 // The result will be 0 if a==b, -1 if a < b, and +1 if a > b.
 func (v Version) Cmp(another Version) int {
 	if v.Ver > another.Ver {
@@ -110,9 +110,9 @@ type Transaction interface {
 	Delete(k Key) error
 	// Commit commites the transaction operations to KV store.
 	Commit() error
-	// CommitVersion returns the verion of this committed transaction. If this
+	// CommittedVersion returns the verion of this committed transaction. If this
 	// transaction has not been committed, returns ErrNotCommitted error.
-	CommitVersion() (Version, error)
+	CommittedVersion() (Version, error)
 	// Rollback undoes the transaction operations to KV store.
 	Rollback() error
 	// String implements Stringer.String() interface.
@@ -124,11 +124,13 @@ type Transaction interface {
 // MvccSnapshot is used to get/seek a specific verion in a snaphot.
 type MvccSnapshot interface {
 	// MvccGet returns the specific version of given key, if the version doesn't
-	// exists, returns the nearest(lower) version's data.
+	// exist, returns the nearest(lower) version's data.
 	MvccGet(k Key, ver Version) ([]byte, error)
 	// MvccIterator seeks to the key in the specific version's snapshot, if the
-	// version doesn't exists, return the nearest(lower) version's snaphot.
+	// version doesn't exist, returns the nearest(lower) version's snaphot.
 	NewMvccIterator(k Key, ver Version) Iterator
+	// Release releases this snapshot.
+	MvccRelease()
 }
 
 // Snapshot defines the interface for the snapshot fetched from KV store.
@@ -153,7 +155,7 @@ type Driver interface {
 type Storage interface {
 	// Begin transaction
 	Begin() (Transaction, error)
-	// MvccSnapshot get a snaphot that cloud read any version of data.
+	// MvccSnapshot get a snaphot that is able to read any version of data.
 	GetMvccSnapshot() (MvccSnapshot, error)
 	// Close store
 	Close() error
diff --git a/store/localstore/mvcc_test.go b/store/localstore/mvcc_test.go
index 1f51db67a1..933d192ddf 100644
--- a/store/localstore/mvcc_test.go
+++ b/store/localstore/mvcc_test.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"time"
 
-	"github.com/ngaut/log"
 	. "github.com/pingcap/check"
 	"github.com/pingcap/tidb/kv"
 	"github.com/pingcap/tidb/store/localstore/goleveldb"
@@ -150,10 +149,11 @@ func (t *testMvccSuite) TestMvccSnapshotGet(c *C) {
 	c.Assert(err, IsNil)
 	err = tx.Commit()
 	c.Assert(err, IsNil)
-	v, err := tx.CommitVersion()
+	v, err := tx.CommittedVersion()
 	c.Assert(err, IsNil)
 
 	mvccSnapshot, err := t.s.GetMvccSnapshot()
+	defer mvccSnapshot.MvccRelease()
 	b, err = mvccSnapshot.MvccGet(kv.EncodeKey(encodeInt(1)), kv.MaxVersion)
 	c.Assert(err, IsNil)
 	c.Assert(string(b), Equals, "new")
@@ -174,17 +174,17 @@ func (t *testMvccSuite) TestMvccSnapshotScan(c *C) {
 	c.Assert(err, IsNil)
 	err = tx.Commit()
 	c.Assert(err, IsNil)
-	v, err := tx.CommitVersion()
+	v, err := tx.CommittedVersion()
 	c.Assert(err, IsNil)
 
 	mvccSnapshot, err := t.s.GetMvccSnapshot()
+	defer mvccSnapshot.MvccRelease()
 	c.Assert(err, IsNil)
 
 	// iter helper function
 	iterFunc := func(it kv.Iterator) bool {
 		found := false
 		for it.Valid() {
-			log.Info(it.Key(), it.Value())
 			if string(it.Value()) == "new" {
 				found = true
 			}
diff --git a/store/localstore/snapshot.go b/store/localstore/snapshot.go
index 3f835a1f5b..37a882db5d 100644
--- a/store/localstore/snapshot.go
+++ b/store/localstore/snapshot.go
@@ -95,6 +95,10 @@ func (s *dbSnapshot) NewIterator(param interface{}) kv.Iterator {
 	return newDBIter(s, k, kv.MaxVersion)
 }
 
+func (s *dbSnapshot) MvccRelease() {
+	s.Release()
+}
+
 func (s *dbSnapshot) Release() {
 	if s.Snapshot != nil {
 		s.Snapshot.Release()
diff --git a/store/localstore/txn.go b/store/localstore/txn.go
index 59862ed7bb..9a0e569c3d 100644
--- a/store/localstore/txn.go
+++ b/store/localstore/txn.go
@@ -227,7 +227,7 @@ func (txn *dbTxn) Commit() error {
 	return txn.doCommit()
 }
 
-func (txn *dbTxn) CommitVersion() (kv.Version, error) {
+func (txn *dbTxn) CommittedVersion() (kv.Version, error) {
 	// Check if this trx is not committed.
 	if txn.version.Cmp(kv.MinVersion) == 0 {
 		return kv.MinVersion, kv.ErrNotCommitted