PDO buffered query problem

Hi there,

I'm having some serious problems with the PHP Data Object functions. I'm 
trying to loop through a sizeable result set (~60k rows, ~1gig) using a 
buffered query to avoid fetching the whole set.

No matter what I do, the script just hangs on the PDO::query() - it 
seems the query is running unbuffered (why else would the change in 
result set size 'fix' the issue?). Here is my code to reproduce the problem:

<?php
$Database = new PDO(
     'mysql:host=localhost;port=3306;dbname=mydatabase',
     'root',
     '',
     array(
         PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
         PDO::MYSQL_ATTR_USE_BUFFERED_QUERY => true
     )
);

$rQuery = $Database->query('SELECT id FROM mytable');

// This is never reached because the result set is too large
echo 'Made it through.';

foreach($rQuery as $aRow) {
     print_r($aRow);
}
?>

If I limit the query with some reasonable number, it works fine:

$rQuery = $Database->query('SELECT id FROM mytable LIMIT 10');

I have tried playing with PDO::MYSQL_ATTR_MAX_BUFFER_SIZE and using the 
PDO::prepare() and PDO::execute() as well (though there are no 
parameters in the above query), both to no avail.

Any help would be appreciated,

Stewart