在订单中保留易失性数据

假设我有表:客户和订单,我想用不可更改的客户信息(如地址、名称等)存储订单,但不想将所有这些信息复制到订单表。有三种选择:

a) Mapping table for base customers
orders
    ....
    customer_id; link to the customers table
    baseCustomer_id; link to the customers_base table
    ....
customers
    id; 
    base_id; link to the base customers table;
    ....
customers_base
    id
    ....

b) Versioning: (if new customer, create version 0 for base customer, and version 1 to have permament record)
orders
    ....
    customer_id
    customer_version
    ....
customers
   id
   version
   ....
c) Create a copy of customer info for each order and store it into the same table; 
orders
   ....
   customer_id
   ....
customers
   id
   ....
   copy_of; refers to the customers.id if null represents base customer entity

因此,问题是:从不同的角度来看,如数据库设计、可读性、实现复杂性,哪种方法更可取?