ddl: don't remove reorg info.

if we remove reorg info but don’t update the DDL status when crashed,
another server will start a whole reorganization again.

ddl/column.go

@@ -319,7 +319,7 @@ func (d *ddl) backfillColumn(t table.Table, columnInfo *model.ColumnInfo, reorgI
 		if err != nil {
 			return errors.Trace(err)
 		} else if len(handles) == 0 {
-			return errors.Trace(reorgInfo.RemoveHandle())
+			return nil
 		}
 
 		seekHandle = handles[len(handles)-1] + 1
@@ -399,7 +399,7 @@ func (d *ddl) dropTableColumn(t table.Table, colInfo *model.ColumnInfo, reorgInf
 		if err != nil {
 			return errors.Trace(err)
 		} else if len(handles) == 0 {
-			return errors.Trace(reorgInfo.RemoveHandle())
+			return nil
 		}
 
 		seekHandle = handles[len(handles)-1] + 1

ddl/index.go

@@ -345,7 +345,7 @@ func (d *ddl) addTableIndex(t table.Table, indexInfo *model.IndexInfo, reorgInfo
 		if err != nil {
 			return errors.Trace(err)
 		} else if len(handles) == 0 {
-			return errors.Trace(reorgInfo.RemoveHandle())
+			return nil
 		}
 
 		seekHandle = handles[len(handles)-1] + 1

ddl/reorg.go

@@ -237,12 +237,3 @@ func (r *reorgInfo) UpdateHandle(txn kv.Transaction, handle int64) error {
 	t := meta.NewMeta(txn)
 	return errors.Trace(t.UpdateDDLReorgHandle(r.Job, handle))
 }
-
-func (r *reorgInfo) RemoveHandle() error {
-	err := kv.RunInNewTxn(r.d.store, true, func(txn kv.Transaction) error {
-		t := meta.NewMeta(txn)
-		err := t.RemoveDDLReorgHandle(r.Job)
-		return errors.Trace(err)
-	})
-	return errors.Trace(err)
-}

ddl/reorg_test.go

@@ -108,9 +108,6 @@ func (s *testDDLSuite) TestReorg(c *C) {
 		return nil
 	})
 	c.Assert(err, IsNil)
-
-	err = info.RemoveHandle()
-	c.Assert(err, IsNil)
 }
 
 func (s *testDDLSuite) TestReorgOwner(c *C) {