Tell me the total quantity of products bought by the customer called "Rodrick Heaney".
select sum(t3.order_quantity) from customers as t1 join customer_orders as t2 on t1.customer_id = t2.customer_id join order_items as t3 on t2.order_id = t3.order_id where t1.customer_name = "Rodrick Heaney"