If a data source does not have a field that can be designated as a primary key, what should the consultant do?

When a source data stream lacks a single, unique field to serve as a primary key, the standard and recommended practice in Salesforce Data Cloud is to create a composite key. This is achieved by creating a new formula field within the data stream. This formula combines the values from two or more source fields to generate a unique identifier for each record. This newly created formula field is then designated as the primary key for the Data Model Object (DMO), ensuring record uniqueness and proper identity resolution.

1. Salesforce Help, "Primary Keys in Data Cloud": "Every DMO must have a primary key... If your data doesn't have a primary key, create one using a formula field that concatenates two or more fields to create a unique value." This directly supports creating a composite key via a formula field.

2. Salesforce Help, "Formula Expressions in Data Cloud": This documentation outlines the capabilities of formula fields, including functions like CONCAT(), which are used to combine multiple field values into a single string, suitable for use as a composite primary key. (See section on "String Functions").

3. Salesforce Help, "Key Qualifiers in Data Cloud": "A key qualifier is a field that is used with the primary key to uniquely identify a record... Use a key qualifier when the field mapped to Primary Key is not unique on its own." This clarifies that a key qualifier augments a selected primary key, which is not possible if no field can be selected as the primary key in the first place, reinforcing why option C is incorrect.