Marketing Cloud: Overwriting AllContacts

Question

We are looking for a way to overwrite the SubscriberKey on an entry journey data extension and on AllContacts on a daily basis before that journey runs.

The DE is populated by an API call from an external site where the unique identifier is not the SF CRM unique identifier and the latter is not present. The requirement is to overwrite the existing identifier on the DE and at the same time on AllContacts with the SF CRM identifier when a match is found.

Can this be achieved through SQL or Script or another method?

Answer 1

As has been said, what you are proposing isn't possible.

I think your best option for the issue is to have a daily automation that uses SQL to return contacts that now have a valid Salesforce CRM ID, some extract and import activities to update All Subscribers for that 'new' record with correct status etc if necessary and some SSJS to delete the 'old' Contacts (that have the external ID as subscriber key) from Marketing Cloud using the DeleteByListReference endpoint.

This can get quite messy and isn't recommended however (you'll lose tracking history and the process may not be robust enough for your needs). It's probably much better to examine the pipeline and see if there's any opportunity to change the process.