Importing/Overwriting a DE that is part of a journey which is triggered by a new campaign member in SF

Question

I have a welcome journey that is triggered by a new campaign member in SF (via connector). The DE that is created as part of the journey does not have a primary key value (though it probably should). During the recent MC outage, we did not do journey sends and I have to catch up missed campaign members added to the journey. I have the data from a query against SF. I can catch up the emails by copying the DE and doing a user initiated send over the top of that. However, I'd rather add the records into the journey and let the journey do it's thing. Plus we'll have an anniversary journey too which would ideally look at this same DE so the missed/catchup data would ideally be in the DE.

Since my underlying DE does not have a primary key, I can't just add the records. I can export all records, add the new records, and import/overwrite the DE. Would this work and would the journey be smart enough to only inject the new records? or, would the journey thing ALL the DE records are new and start everyone over (which I don't want).

Answer 1

If you overwrite all records in the existing DE, then the platform will clear the high watermark (which is used to identify new records added to your event source DE). As a result, all records will be re-injected into the Journey.

I'm not sure what messaging activities are in your journey, but if it's only email activities, then you could create a Suppression List of Contacts who have previously been admitted into the journey, then update the existing send email activities and select the suppression list under 'Delivery Options' to ensure that emails aren't sent to them.