diff --git a/kv/kv.go b/kv/kv.go
index 874847f0ee..0e3f52c08b 100644
--- a/kv/kv.go
+++ b/kv/kv.go
@@ -15,6 +15,7 @@ package kv
 
 import (
 	"bytes"
+	"errors"
 	"math"
 )
 
@@ -73,12 +74,27 @@ func NewVersion(v uint64) Version {
 	}
 }
 
+// Cmp returns the comparison result of two version.
+// 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 {
+		return 1
+	} else if v.Ver < another.Ver {
+		return -1
+	}
+	return 0
+}
+
 // DecodeFn is a function that decode data after fetch from store.
 type DecodeFn func(raw interface{}) (interface{}, error)
 
 // EncodeFn is a function that encode data before put into store.
 type EncodeFn func(raw interface{}) (interface{}, error)
 
+// ErrNotCommitted is the error returned by CommitVersion when the this
+// transaction is not committed.
+var ErrNotCommitted = errors.New("this transaction is not committed")
+
 // Transaction defines the interface for operations inside a Transaction.
 // This is not thread safe.
 type Transaction interface {
@@ -93,7 +109,10 @@ type Transaction interface {
 	// Deletes removes the entry for key k from KV store.
 	Delete(k Key) error
 	// Commit commites the transaction operations to KV store.
-	Commit() (Version, error)
+	Commit() error
+	// CommitVersion returns the verion of this committed transaction. If this
+	// transaction has not been committed, returns ErrNotCommitted error.
+	CommitVersion() (Version, error)
 	// Rollback undoes the transaction operations to KV store.
 	Rollback() error
 	// String implements Stringer.String() interface.
diff --git a/kv/txn.go b/kv/txn.go
index e722298bc1..2d33c90870 100644
--- a/kv/txn.go
+++ b/kv/txn.go
@@ -51,7 +51,7 @@ func RunInNewTxn(store Storage, retryable bool, f func(txn Transaction) error) e
 			return errors.Trace(err)
 		}
 
-		_, err = txn.Commit()
+		err = txn.Commit()
 		if retryable && IsRetryableError(err) {
 			log.Warnf("Retry txn %v", txn)
 			txn.Rollback()
diff --git a/session.go b/session.go
index 6d89f22285..4fff174146 100644
--- a/session.go
+++ b/session.go
@@ -143,7 +143,7 @@ func (s *session) FinishTxn(rollback bool) error {
 		return s.txn.Rollback()
 	}
 
-	_, err := s.txn.Commit()
+	err := s.txn.Commit()
 	if err != nil {
 		log.Warnf("txn:%s, %v", s.txn, err)
 		return errors.Trace(err)
@@ -346,7 +346,7 @@ func (s *session) GetTxn(forceNew bool) (kv.Transaction, error) {
 		return s.txn, nil
 	}
 	if forceNew {
-		_, err = s.txn.Commit()
+		err = s.txn.Commit()
 		variable.GetSessionVars(s).SetStatusFlag(mysql.ServerStatusInTrans, false)
 		if err != nil {
 			return nil, err
diff --git a/store/localstore/kv.go b/store/localstore/kv.go
index 955ae11525..da734f86e2 100644
--- a/store/localstore/kv.go
+++ b/store/localstore/kv.go
@@ -123,6 +123,7 @@ func (s *dbStore) Begin() (kv.Transaction, error) {
 		tID:          beginVer.Ver,
 		valid:        true,
 		store:        s,
+		version:      kv.MinVersion,
 		snapshotVals: make(map[string][]byte),
 	}
 	log.Debugf("Begin txn:%d", txn.tID)
diff --git a/store/localstore/kv_test.go b/store/localstore/kv_test.go
index 0ca55421e7..d09c35043d 100644
--- a/store/localstore/kv_test.go
+++ b/store/localstore/kv_test.go
@@ -151,7 +151,7 @@ func (s *testKVSuite) TestGetSet(c *C) {
 	mustGet(c, txn)
 
 	// Check transaction results
-	_, err = txn.Commit()
+	err = txn.Commit()
 	c.Assert(err, IsNil)
 
 	txn, err = s.s.Begin()
@@ -170,7 +170,7 @@ func (s *testKVSuite) TestSeek(c *C) {
 	checkSeek(c, txn)
 
 	// Check transaction results
-	_, err = txn.Commit()
+	err = txn.Commit()
 	c.Assert(err, IsNil)
 
 	txn, err = s.s.Begin()
@@ -191,7 +191,7 @@ func (s *testKVSuite) TestInc(c *C) {
 	c.Assert(n, Equals, int64(100))
 
 	// Check transaction results
-	_, err = txn.Commit()
+	err = txn.Commit()
 	c.Assert(err, IsNil)
 
 	txn, err = s.s.Begin()
@@ -211,7 +211,7 @@ func (s *testKVSuite) TestInc(c *C) {
 	err = txn.Delete(key)
 	c.Assert(err, IsNil)
 
-	_, err = txn.Commit()
+	err = txn.Commit()
 	c.Assert(err, IsNil)
 }
 
@@ -431,7 +431,7 @@ func (s *testKVSuite) TestConditionIfNotExist(c *C) {
 			if err != nil {
 				return
 			}
-			_, err = txn.Commit()
+			err = txn.Commit()
 			if err == nil {
 				atomic.AddInt64(&success, 1)
 			}
@@ -445,7 +445,7 @@ func (s *testKVSuite) TestConditionIfNotExist(c *C) {
 	c.Assert(err, IsNil)
 	err = txn.Delete(b)
 	c.Assert(err, IsNil)
-	_, err = txn.Commit()
+	err = txn.Commit()
 	c.Assert(err, IsNil)
 }
 
@@ -459,7 +459,7 @@ func (s *testKVSuite) TestConditionIfEqual(c *C) {
 	txn, err := s.s.Begin()
 	c.Assert(err, IsNil)
 	txn.Set(b, b)
-	_, err = txn.Commit()
+	err = txn.Commit()
 	c.Assert(err, IsNil)
 
 	for i := 0; i < cnt; i++ {
@@ -470,7 +470,7 @@ func (s *testKVSuite) TestConditionIfEqual(c *C) {
 			txn1, err1 := s.s.Begin()
 			c.Assert(err1, IsNil)
 			txn1.Set(b, []byte("newValue"))
-			_, err1 = txn1.Commit()
+			err1 = txn1.Commit()
 			if err1 == nil {
 				atomic.AddInt64(&success, 1)
 			}
@@ -484,7 +484,7 @@ func (s *testKVSuite) TestConditionIfEqual(c *C) {
 	c.Assert(err, IsNil)
 	err = txn.Delete(b)
 	c.Assert(err, IsNil)
-	_, err = txn.Commit()
+	err = txn.Commit()
 	c.Assert(err, IsNil)
 }
 
@@ -493,6 +493,6 @@ func (s *testKVSuite) TestConditionUpdate(c *C) {
 	c.Assert(err, IsNil)
 	txn.Delete([]byte("b"))
 	txn.Inc([]byte("a"), 1)
-	_, err = txn.Commit()
+	err = txn.Commit()
 	c.Assert(err, IsNil)
 }
diff --git a/store/localstore/mvcc_test.go b/store/localstore/mvcc_test.go
index cd9d70e3ed..f5bd55f84c 100644
--- a/store/localstore/mvcc_test.go
+++ b/store/localstore/mvcc_test.go
@@ -148,7 +148,9 @@ func (t *testMvccSuite) TestMvccSnapshotGet(c *C) {
 	tx, _ = t.s.Begin()
 	err = tx.Set(encodeInt(1), []byte("new"))
 	c.Assert(err, IsNil)
-	v, err := tx.Commit()
+	err = tx.Commit()
+	c.Assert(err, IsNil)
+	v, err := tx.CommitVersion()
 	c.Assert(err, IsNil)
 
 	mvccSnapshot, err := t.s.GetMvccSnapshot()
@@ -170,7 +172,9 @@ func (t *testMvccSuite) TestMvccSnapshotScan(c *C) {
 	tx, _ := t.s.Begin()
 	err := tx.Set(encodeInt(1), []byte("new"))
 	c.Assert(err, IsNil)
-	v, err := tx.Commit()
+	err = tx.Commit()
+	c.Assert(err, IsNil)
+	v, err := tx.CommitVersion()
 	c.Assert(err, IsNil)
 
 	mvccSnapshot, err := t.s.GetMvccSnapshot()
diff --git a/store/localstore/txn.go b/store/localstore/txn.go
index 5a65c99b23..59862ed7bb 100644
--- a/store/localstore/txn.go
+++ b/store/localstore/txn.go
@@ -41,6 +41,7 @@ type dbTxn struct {
 	startTs      time.Time
 	tID          uint64
 	valid        bool
+	version      kv.Version        // commit version
 	snapshotVals map[string][]byte // origin version in snapshot
 }
 
@@ -172,7 +173,7 @@ func (txn *dbTxn) each(f func(iterator.Iterator) error) error {
 	return nil
 }
 
-func (txn *dbTxn) doCommit() (kv.Version, error) {
+func (txn *dbTxn) doCommit() error {
 	b := txn.store.newBatch()
 	keysLocked := make([]string, 0, len(txn.snapshotVals))
 	defer func() {
@@ -184,7 +185,7 @@ func (txn *dbTxn) doCommit() (kv.Version, error) {
 	for k, v := range txn.snapshotVals {
 		err := txn.store.tryConditionLockKey(txn.tID, k, v)
 		if err != nil {
-			return kv.MinVersion, errors.Trace(err)
+			return errors.Trace(err)
 		}
 		keysLocked = append(keysLocked, k)
 	}
@@ -192,7 +193,7 @@ func (txn *dbTxn) doCommit() (kv.Version, error) {
 	// Check dirty store
 	curVer, err := globalVersionProvider.CurrentVersion()
 	if err != nil {
-		return kv.MinVersion, errors.Trace(err)
+		return errors.Trace(err)
 	}
 	err = txn.each(func(iter iterator.Iterator) error {
 		metaKey := codec.EncodeBytes(nil, iter.Key())
@@ -207,14 +208,16 @@ func (txn *dbTxn) doCommit() (kv.Version, error) {
 		return nil
 	})
 	if err != nil {
-		return kv.MinVersion, errors.Trace(err)
+		return errors.Trace(err)
 	}
-	return curVer, txn.store.writeBatch(b)
+	// Update commit version.
+	txn.version = curVer
+	return txn.store.writeBatch(b)
 }
 
-func (txn *dbTxn) Commit() (kv.Version, error) {
+func (txn *dbTxn) Commit() error {
 	if !txn.valid {
-		return kv.MinVersion, ErrInvalidTxn
+		return ErrInvalidTxn
 	}
 	log.Infof("commit txn %d", txn.tID)
 	defer func() {
@@ -224,6 +227,14 @@ func (txn *dbTxn) Commit() (kv.Version, error) {
 	return txn.doCommit()
 }
 
+func (txn *dbTxn) CommitVersion() (kv.Version, error) {
+	// Check if this trx is not committed.
+	if txn.version.Cmp(kv.MinVersion) == 0 {
+		return kv.MinVersion, kv.ErrNotCommitted
+	}
+	return txn.version, nil
+}
+
 func (txn *dbTxn) close() error {
 	txn.UnionStore.Close()
 	txn.snapshotVals = nil
diff --git a/util/prefix_helper_test.go b/util/prefix_helper_test.go
index 43c3d08af9..d201cb6c97 100644
--- a/util/prefix_helper_test.go
+++ b/util/prefix_helper_test.go
@@ -115,8 +115,7 @@ func (c *MockContext) FinishTxn(rollback bool) error {
 		return nil
 	}
 
-	_, err := c.txn.Commit()
-	return err
+	return c.txn.Commit()
 }
 
 func (s *testPrefixSuite) TestPrefix(c *C) {
@@ -134,7 +133,7 @@ func (s *testPrefixSuite) TestPrefix(c *C) {
 	c.Assert(err, IsNil)
 	err = ScanMetaWithPrefix(txn, str, func([]byte, []byte) bool { return true })
 	c.Assert(err, IsNil)
-	_, err = txn.Commit()
+	err = txn.Commit()
 	c.Assert(err, IsNil)
 }