I have the following recursive function which works... up until a point. Then the script asks for more memory once the queries exceed about 100, and when I add more memory, the script typically just dies (I end up with a white screen on my browser).

public function returnPArray($parent=0,$depth=0,$orderBy = 'showOrder ASC'){



    $query = mysql_query("SELECT *, UNIX_TIMESTAMP(lastDate) AS whenTime 
        FROM these_pages 
        WHERE parent = '".$parent."' AND deleted = 'N' ORDER BY ".$orderBy."");

    $rows = mysql_num_rows($query);

    while($row = mysql_fetch_assoc($query)){

        // This uses my class and places the content in an array.
        MyClass::$_navArray[] = array(

            'id' => $row['id'], 
            'parent' => $row['parent']

        );

        MyClass::returnPArray($row['id'],($depth+1));   

    }
    $i++;

}

Can anyone help me make this query less resource intensive?