Subscribers perform on action on a website. The subscriber record is then added into a Triggered Data Extension and an email is sent out as part of the API call / Triggered Email Interaction. Tried, true, tested.
I am wondering if when the API call is made inserting the subscriber into the Triggered Send Data Extension, if it could update that subscribe's record if it found a matching Primary Key? So for example, we add an additional attribute into the Data Extension and make it the Primary Key, and when that API call runs it either adds a new record or updates the existing one based on the Primary Key passed through the API call.
I've tested it out and all email sends are stuck in queueing for the triggered email interaction, leading me to believe it wasn't happy with the Primary Key.
Before sinking in more hours on what may be a lost cause I thought to check if anyone has ever attempted this before, and if so what results they found.