refactor the job args for add column ddl.

Signed-off-by: joccau <[email protected]>

pkg/ddl/column.go

@@ -72,15 +72,13 @@ func checkAddColumn(t *meta.Meta, job *model.Job) (*model.TableInfo, *model.Colu
 	if err != nil {
 		return nil, nil, nil, nil, false, errors.Trace(err)
 	}
-	col := &model.ColumnInfo{}
-	pos := &ast.ColumnPosition{}
-	offset := 0
-	ifNotExists := false
-	err = job.DecodeArgs(col, pos, &offset, &ifNotExists)
+
+	args, err := model.GetAddColumnArgs(job)
 	if err != nil {
 		job.State = model.JobStateCancelled
 		return nil, nil, nil, nil, false, errors.Trace(err)
 	}
+	col, pos, ifNotExists := args.Col, args.Pos, args.IfNotExists
 
 	columnInfo := model.FindColumnInfo(tblInfo.Columns, col.Name.L)
 	if columnInfo != nil {

pkg/ddl/executor.go

@@ -2261,18 +2261,24 @@ func (e *executor) AddColumn(ctx sessionctx.Context, ti ast.Ident, spec *ast.Alt
 	}
 
 	job := &model.Job{
+		Version:        model.JobVersion1,
 		SchemaID:       schema.ID,
 		TableID:        tbInfo.ID,
 		SchemaName:     schema.Name.L,
 		TableName:      tbInfo.Name.L,
 		Type:           model.ActionAddColumn,
 		BinlogInfo:     &model.HistoryInfo{},
-		Args:           []any{col, spec.Position, 0, spec.IfNotExists},
 		CDCWriteSource: ctx.GetSessionVars().CDCWriteSource,
 		SQLMode:        ctx.GetSessionVars().SQLMode,
 	}
-
-	err = e.DoDDLJob(ctx, job)
+	args := &model.AddColumnArgs{
+		Col:         col.ColumnInfo,
+		Pos:         spec.Position,
+		Offset:      0,
+		IfNotExists: spec.IfNotExists,
+	}
+	job.FillArgs(args)
+	err = e.doDDLJob2(ctx, job, args)
 	return errors.Trace(err)
 }
 

pkg/ddl/multi_schema_change.go

@@ -200,8 +200,8 @@ func appendToSubJobs(m *model.MultiSchemaInfo, jobW *JobWrapper) error {
 func fillMultiSchemaInfo(info *model.MultiSchemaInfo, job *JobWrapper) error {
 	switch job.Type {
 	case model.ActionAddColumn:
-		col := job.Args[0].(*table.Column)
-		pos := job.Args[1].(*ast.ColumnPosition)
+		args := job.JobArgs.(*model.AddColumnArgs)
+		col, pos := args.Col, args.Pos
 		info.AddColumns = append(info.AddColumns, col.Name)
 		for colName := range col.Dependences {
 			info.RelativeColumns = append(info.RelativeColumns, pmodel.CIStr{L: colName, O: colName})

pkg/meta/model/job_args.go

@@ -1121,3 +1121,41 @@ func GetSetDefaultValueArgs(job *Job) (*SetDefaultValueArgs, error) {
 
 	return getOrDecodeArgsV2[*SetDefaultValueArgs](job)
 }
+
+// AddColumnArgs is the arguments for adding column ddl.
+type AddColumnArgs struct {
+	Col         *ColumnInfo
+	Pos         *ast.ColumnPosition
+	Offset      int
+	IfNotExists bool
+}
+
+func (a *AddColumnArgs) fillJob(job *Job) {
+	if job.Version == JobVersion1 {
+		job.Args = []any{a.Col, a.Pos, a.Offset, a.IfNotExists}
+	} else {
+		job.Args = []any{a}
+	}
+}
+
+func GetAddColumnArgs(job *Job) (*AddColumnArgs, error) {
+	if job.Version == JobVersion1 {
+		var (
+			col         = &ColumnInfo{}
+			pos         = &ast.ColumnPosition{}
+			offset      = 0
+			ifNotExists = false
+		)
+		if err := job.DecodeArgs(col, pos, &offset, &ifNotExists); err != nil {
+			return nil, errors.Trace(err)
+		}
+		return &AddColumnArgs{
+			Col:         col,
+			Pos:         pos,
+			Offset:      offset,
+			IfNotExists: ifNotExists,
+		}, nil
+	}
+
+	return getOrDecodeArgsV2[*AddColumnArgs](job)
+}

pkg/meta/model/job_args_test.go

@@ -657,3 +657,24 @@ func TestGetSetDefaultValueArgs(t *testing.T) {
 		require.Equal(t, inArgs, args)
 	}
 }
+
+func TestGetAddColumnArgs(t *testing.T) {
+	inArgs := &AddColumnArgs{
+		Col: &ColumnInfo{
+			ID:   7527,
+			Name: model.NewCIStr("col_name"),g
+		},
+		Pos: &ast.ColumnPosition{
+			Tp: ast.ColumnPositionFirst,
+		},
+		Offset:      1001,
+		IfNotExists: true,
+	}
+	for _, v := range []JobVersion{JobVersion1, JobVersion2} {
+		j2 := &Job{}
+		require.NoError(t, j2.Decode(getJobBytes(t, inArgs, v, ActionAddColumn)))
+		args, err := GetAddColumnArgs(j2)
+		require.NoError(t, err)
+		require.Equal(t, inArgs, args)
+	}
+}