subpartitioning or star schema transformation

Hello

I have a doubt about composite partitioning and star schema transformation.

Imagine the classic scenario fact SALES and dimension CUSTOMER where

I would like to partition SALES by Range (event date)  and subpartition by LIST (country code).

and dimension CUSTOMER partition by LIST (country code).

So could happen partition wise joins.

and for that happen I will need to add in the inner join between "sales-customer"   the "country code" column.

==> INNER JOIN f.customer_id c.customer_id AND  f.country_code c.country_code

But for star schema transformation happen,  documentation says that only one column should be use for the join between fact and dimension.