Is there a way to fire event for only one among 2 or more Journeys using Same Data Extension as Entry Source

Question

I have 2 or more journeys using same DEs as Entry Source but different entry criteria.
If i create a fire event and trigger that DE, does it differentiate between which Journeys it would trigger contacts injection into. What if I create API Trigger for them.. will it differentiate.

I am asking this because salesforce support has this to say for troubleshooting a journey we were having issues with:

create a new entry event with the same criteria. Upon doing this, you will not encounter issues with the other entries running off of the same data extension. Separate entry events utilize independent highwatermarks.

Further they said this:

The highwatermark is based off of the entry event and not solely the data extension. Each entry contains its own highwatermark.

Pls advise.

Answer 1

As the support representative correctly advises, if you used the same DE as the Event Source, then the Contacts that you added to the DE will enter all journeys associated with that Event Source, (providing that they meet the Entry Criteria defined within each Event).

Note that each time you add new records to the Event Source DE and fire the Event, then a 'high watermark' will be set, so only new Contacts that are added to the Event Source DE will be injected in the Journey the next time the Event is fired. So, for example, if you have scheduled the Events to run at different times (within the Event), then different high watermarks will be set for each Event, which is nice.

Regarding the 'API Trigger', note that when you use the Events method you have to define the EventDefinitionKey of the Event, so you can't inject a Contact into multiple Journeys from a single request; you would need to make multiple requests. This will still inject them into the respective Journey (based on EventDefinitionKey) and add the record to the Event Source DE, but you might have issues if you try and add a duplicate a record (due to primary key violation). If you just need to inject a Contact into a second journey, then you can use an empty data object in your request payload. If you let me know what exactly you are trying to achieve with the API, I can elaborate further.