func()

in pkg/datasource/sql/undo/builder/mysql_update_undo_log_builder.go [172:241]
62 lines of code
6 McCabe index (conditional complexity)

func (u *MySQLUpdateUndoLogBuilder) buildBeforeImageSQL(ctx context.Context, execCtx *types.ExecContext, args []driver.Value) (string, []driver.Value, error) {
	updateStmt := execCtx.ParseContext.UpdateStmt
	if updateStmt == nil {
		log.Errorf("invalid update stmt")
		return "", nil, fmt.Errorf("invalid update stmt")
	}

	fields := make([]*ast.SelectField, 0, len(updateStmt.List))

	// todo: OnlyCareUpdateColumns should load from config first
	if OnlyCareUpdateColumns {
		for _, column := range updateStmt.List {
			fields = append(fields, &ast.SelectField{
				Expr: &ast.ColumnNameExpr{
					Name: column.Column,
				},
			})
		}

		// select indexes columns
		tableName, _ := execCtx.ParseContext.GetTableName()
		metaData, err := datasource.GetTableCache(types.DBTypeMySQL).GetTableMeta(ctx, execCtx.DBName, tableName)
		if err != nil {
			return "", nil, err
		}
		for _, columnName := range metaData.GetPrimaryKeyOnlyName() {
			fields = append(fields, &ast.SelectField{
				Expr: &ast.ColumnNameExpr{
					Name: &ast.ColumnName{
						Name: model.CIStr{
							O: columnName,
							L: columnName,
						},
					},
				},
			})
		}
	} else {
		fields = append(fields, &ast.SelectField{
			Expr: &ast.ColumnNameExpr{
				Name: &ast.ColumnName{
					Name: model.CIStr{
						O: "*",
						L: "*",
					},
				},
			},
		})
	}

	selStmt := ast.SelectStmt{
		SelectStmtOpts: &ast.SelectStmtOpts{},
		From:           updateStmt.TableRefs,
		Where:          updateStmt.Where,
		Fields:         &ast.FieldList{Fields: fields},
		OrderBy:        updateStmt.Order,
		Limit:          updateStmt.Limit,
		TableHints:     updateStmt.TableHints,
		LockInfo: &ast.SelectLockInfo{
			LockType: ast.SelectLockForUpdate,
		},
	}

	b := bytes.NewByteBuffer([]byte{})
	_ = selStmt.Restore(format.NewRestoreCtx(format.RestoreKeyWordUppercase, b))
	sql := string(b.Bytes())
	log.Infof("build select sql by update sourceQuery, sql {%s}", sql)

	return sql, u.buildSelectArgs(&selStmt, args), nil
}