Oracle - Como se crea una dimension con 2 tablas?

Resulta que quiero crear una dimension a partir de 2 tablas.
Este codigo es correcto?
CREATE DIMENSION customers_dim
LEVEL customer IS (customers.cust_id)
LEVEL city IS (customers.cust_city)
LEVEL state IS (customers.cust_state_province)
LEVEL country IS (countries.country_id)
LEVEL subregion IS (countries.country_subregion)
LEVEL region IS (countries.country_region)
HIERARCHY geog_rollup (
customer CHILD OF
city CHILD OF
state CHILD OF
country CHILD OF
subregion CHILD OF
region
JOIN KEY (customers.country_id) REFERENCES country
)
ATTRIBUTE customer DETERMINES
(cust_first_name, cust_last_name, cust_gender,
cust_marital_status, cust_year_of_birth,
cust_income_level, cust_credit_limit)
ATTRIBUTE country DETERMINES (countries.country_name)

El Join Key, attribute y References que funciones cumplen? No he encontrado nada en google. Explicadmelo por favor por encima. Gracias.