Yes, I double checked just now. But I did add it.
function add_cond_to_where( $where ) {
$where = str_replace("meta_key = 'data_$", "meta_key LIKE 'data_%", $where);
return $where;
}
add_filter('posts_where', 'add_cond_to_where');
Is in my functions.php. Anyway I can test if it works?