In common case, column component in a data table rendered as a table cells for each row. On other hand, at least a Microsoft Internet Explorer browsers don't allow to manipulate rows/cells as a dom element. For a your case, update entire table.
can you post the simple example of the whole table update? (inclusive columns and columnsgroup)
i'm receive in my bean only data items get request. But this is only the data, not the header :( (not the column)