getBean parameters not behaving the way I would expect.

I was excited to find in Link2.php that getBeans can take parameters to filter the beans that are retrieved.

I want to get the latest related record in code.

I was hoping to get it by ordering by date_modified and using a limit of 1

$filter = array(
    'order_by'=>'date_modified desc',
    'limit' => '1'
);
$bean = $recordBean->$link->getBeans($filter)

Similarly to what I would expect from a query like

select * from accounts
order by date_modified desc
limit  1

But it's not giving me the result I expected. It seems to be getting one seemingly random record and ignoring the sort.

I can get records newer than a given date by adding a where clause so the parameters are indeed being considered.

    $filter = array(
      'where' => array(
      'lhs_field' => 'date_modified',
      'operator' => '>=',
      'rhs_value' => $date)
    );

Any thoughts on ways to get the latest without having to get them all, sort them and then get one?

I'm trying to limit how much data I pull, there could be thousands of related records.

thanks,

Francesca