Contact identifiers

In the section Entity facets, the membership id for a customer loyalty program was set as a property on a contact facet. If you do not need to search for a contact using the membership id, a contact facet is a good place to store the value.

However, if you expect to search for a contact using the membership id, you will want to add the value as an identifier on the contact. This section explains how to configure xDB Data Migration Tool to create a custom contact identifier using the membership id.