内存超过了PHP进程

Question

此过程超出了php的3GB内存限制，我无法扩展内存限制

$query = "select id from clients order by id asc";
            $clients = $storage->executeSQL($query,\PDO::FETCH_OBJ);

            foreach ($clients as $client){
                $percentage = $stats->getCompletitionById($client->id);
                $update = "UPDATE clients SET profile_percentage = ".$percentage." WHERE id = ".$client->id;

                $storage->executeSQL($update, \PDO::FETCH_OBJ, array(), true);

            }

在php或doctrine（executeSQL函数使用原则）中，有任何方法可以释放较长时间的内存