Nested Tables - Why?

I have been looking at nested tables for one particular situation I have but I must say despiter reading the docs I still dont see WHY anyone would use a nested table.
I mean basically they dont seem to me to be any differeent from a master/detail relationship between two traditional relational tables EXCEPT they are now harder to query or update and I assume will be much slower to query.

Assuming there is something I am not getting here I wondered if someone could enlighten me to the benefits of using a nested table.

The situation I have is that I am storing costs associated with a bill of materials for certain products and it seemed like the alternatives were a master "product" table and a detail table containing all the associated costs linked by productid to the master table OR to use a nested table "cost" column in the master table. It will be very rare that the data is edited as fresh cost entires will be added into the table each month from another table rather than editing this table. Queries will usually want to total the cost or to display them for detailed reports.

Thanks
Rob Received on Tue Jul 06 1999 - 02:42:15 CDT