diff --git a/ddl/index.go b/ddl/index.go
index 458a68a208..41f4348b5d 100644
--- a/ddl/index.go
+++ b/ddl/index.go
@@ -29,7 +29,7 @@ import (
 	"github.com/pingcap/tidb/util/errors2"
 )
 
-func (d *ddl) checkTablePublic(t *meta.Meta, job *model.Job) (*model.TableInfo, error) {
+func (d *ddl) getTableInfo(t *meta.Meta, job *model.Job) (*model.TableInfo, error) {
 	schemaID := job.SchemaID
 	tableID := job.TableID
 	tblInfo, err := t.GetTable(schemaID, tableID)
@@ -104,8 +104,7 @@ func buildIndexInfo(tblInfo *model.TableInfo, unique bool, indexName model.CIStr
 
 func (d *ddl) onIndexCreate(t *meta.Meta, job *model.Job) error {
 	schemaID := job.SchemaID
-
-	tblInfo, err := d.checkTablePublic(t, job)
+	tblInfo, err := d.getTableInfo(t, job)
 	if err != nil {
 		return errors.Trace(err)
 	}
@@ -214,8 +213,7 @@ func (d *ddl) onIndexCreate(t *meta.Meta, job *model.Job) error {
 
 func (d *ddl) onIndexDrop(t *meta.Meta, job *model.Job) error {
 	schemaID := job.SchemaID
-
-	tblInfo, err := d.checkTablePublic(t, job)
+	tblInfo, err := d.getTableInfo(t, job)
 	if err != nil {
 		return errors.Trace(err)
 	}
@@ -264,8 +262,7 @@ func (d *ddl) onIndexDrop(t *meta.Meta, job *model.Job) error {
 		return errors.Trace(err)
 	case model.StateReorgnization:
 		// reorganization -> absent
-		var tbl table.Table
-		tbl, err = d.getTable(t, schemaID, tblInfo)
+		tbl, err := d.getTable(t, schemaID, tblInfo)
 		if err != nil {
 			return errors.Trace(err)
 		}
diff --git a/ddl/reorg.go b/ddl/reorg.go
index 763c1b469c..106712de7c 100644
--- a/ddl/reorg.go
+++ b/ddl/reorg.go
@@ -97,7 +97,6 @@ const waitReorgTimeout = 10 * time.Second
 var errWaitReorgTimeout = errors.New("wait for reorgnization timeout")
 
 func (d *ddl) runReorgJob(f func() error) error {
-	// wait reorgnization jobs done
 	// TODO use persistent reorgnization job list.
 	if d.reOrgDoneCh == nil {
 		// start a reorgnization job
diff --git a/ddl/worker.go b/ddl/worker.go
index aa6aa092dd..c5d5e760b5 100644
--- a/ddl/worker.go
+++ b/ddl/worker.go
@@ -294,7 +294,9 @@ func (d *ddl) runJob(t *meta.Meta, job *model.Job) error {
 	case model.ActionDropIndex:
 		err = d.onIndexDrop(t, job)
 	case model.ActionAddConstraint:
+		log.Fatal("Doesn't support change constraint online")
 	case model.ActionDropConstraint:
+		log.Fatal("Doesn't support change constraint online")
 	default:
 		// invalid job, cancel it.
 		job.State = model.JobCancelled
diff --git a/meta/meta.go b/meta/meta.go
index 97ee0b2c89..cf440f0793 100644
--- a/meta/meta.go
+++ b/meta/meta.go
@@ -20,6 +20,7 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+	"time"
 
 	"github.com/juju/errors"
 	"github.com/pingcap/tidb/kv"
@@ -260,9 +261,8 @@ func (m *Meta) CreateTable(dbID int64, tableInfo *model.TableInfo) error {
 
 // DropDatabase drops whole database.
 func (m *Meta) DropDatabase(dbID int64) error {
-	// first check db exists or not.
+	// check if db exists.
 	dbKey := m.dbKey(dbID)
-
 	if err := m.txn.HClear(dbKey); err != nil {
 		return errors.Trace(err)
 	}
@@ -283,7 +283,6 @@ func (m *Meta) DropTable(dbID int64, tableID int64) error {
 	}
 
 	tableKey := m.tableKey(tableID)
-
 	// then check table exists or not
 	if err := m.checkTableExists(dbKey, tableKey); err != nil {
 		return errors.Trace(err)
@@ -398,7 +397,6 @@ func (m *Meta) GetTable(dbID int64, tableID int64) (*model.TableInfo, error) {
 	}
 
 	tableKey := m.tableKey(tableID)
-
 	value, err := m.txn.HGet(dbKey, tableKey)
 	if err != nil || value == nil {
 		return nil, errors.Trace(err)
@@ -479,6 +477,8 @@ func (m *Meta) GetDDLJob(index int64) (*model.Job, error) {
 
 // UpdateDDLJob updates the DDL job with index.
 func (m *Meta) UpdateDDLJob(index int64, job *model.Job) error {
+	// TODO: use timestamp allocated by TSO
+	job.LastUpdateTS = time.Now().Unix()
 	b, err := job.Encode()
 	if err != nil {
 		return errors.Trace(err)
diff --git a/model/ddl.go b/model/ddl.go
index 2d33aa1db8..33ee20554f 100644
--- a/model/ddl.go
+++ b/model/ddl.go
@@ -78,7 +78,8 @@ type Job struct {
 	RawArgs     json.RawMessage `json:"raw_args"`
 	SchemaState SchemaState     `json:"schema_state"`
 	// snapshot version for this job.
-	SnapshotVer uint64 `json:"snapshot_ver"`
+	SnapshotVer  uint64 `json:"snapshot_ver"`
+	LastUpdateTS int64  `json:"last_update_ts"`
 }
 
 // Encode encodes job with json format.