Subquery in a Materialized View

Question

I have a requirement where we have to build a summary view to show a customer's latest transaction. There can be several million customers so I am thinking if a Materialized view that gets refreshed once every day is a good option here. This is a Datawarehouse application where the records get appended once every day. I would like a summarized materialized view that is dropped and refreshed every day morning.
Here is the query that gets the latest order amount for each of the customer:
SELECT cu.cust_name,
od.order_amount
FROM customers cu,
orders od
WHERE cu.cust_id = od.cust_id
and od.order_date =
(select max(order_date) from orders od
where od.cust_id = cu.cust_id)
My questions are:
1) Is the materialized view a snapshot? Or does it go against the underlying table every time the MV is accessed, much like a regular view?
2) I would like a snapshot type of solution here. Since there could be 100 million orders for 1 million customers, a summary snapshot of 1 million records would perform much better IMO. Correct me if I got it wrong.
Thank you in advance for your help.

Answer 1

Users query will be explicitly against the Mview.
After doing some reading on the MView, I am more inclined to think that Mview is not an ideal solution for my requirement here.
SELECT cu.cust_name,
od.order_amount,
MAX(od.order_date) over (PARTITION BY od.cust_id) max_date
FROM customers cu,
orders od
WHERE cu.cust_id = od.cust_id
The orders is a 20+ million records table. I thought by using a Mview that holds the maximum order date will avoid going to the orders table when users want to see that is the latest order date for a customer. However, the report requirements are such that the users will want to see what is the maximum order date within a certain date range. If this being the case, there is no point in using an Mview.
Once again, pl correct me if my understanding is not correct.