A data architect needs to create an app that combines employee data from the Sales system and the Human Resources (HR) system.

These systems identify employees differently Employees in the HR system are identified with an alpha-numeric key Employees in the Sales system are identified using an integer key.

The Human Resources manager creates a table that maps these keys to another, called Associations.

The resultant data model must meet the following requirements:

• Associations must be valid

• The model must be optimized for performance

• The option must support multiple tables added

Which solution should the data architect use to meet these requirements?