Using REF Values for Retrieval of Data
One limiting aspect of the referential integrity
days in relational databases was that you had to join tables by
their key values to retrieve related rows of data from two tables.
Through the use of a REF value, there is no need to perform a join
since you already have the unique identifier for the object row you
wish to retrieve stored in the child table. This means that the
driver for queries will be from the child to the parent.