code: func ConvertOldVersionUTF8ToUTF8MB4IfNeed(tbInfo *model.TableInfo) {
  	if tbInfo.Version >= model.TableInfoVersion2 || !config.GetGlobalConfig().TreatOldVersionUTF8AsUTF8MB4 {
  		return
  	}
  	if tbInfo.Charset == charset.CharsetUTF8 {
  		tbInfo.Charset = charset.CharsetUTF8MB4
  		tbInfo.Collate = charset.CollationUTF8MB4
  	}
  	for _, col := range tbInfo.Columns {
  		if col.Version < model.ColumnInfoVersion2 && col.Charset == charset.CharsetUTF8 {
  			col.Charset = charset.CharsetUTF8MB4
  			col.Collate = charset.CollationUTF8MB4
  		}
  	}
  }
docs: // ConvertOldVersionUTF8ToUTF8MB4IfNeed convert old version UTF8 to UTF8MB4 if config.TreatOldVersionUTF8AsUTF8MB4 is enable.