Hello,
I'm new to RapidMiner so bear with me
I'm trying to do a rather simple process in which I use
de-pivot (aka "melt") an example set and then use the result example set in a join operation.
The de-pivot works exactly as I'd expected but the follow up join does not find the newly created column which I'd like to use as key attribute.
My input example set is a list of transactions (see attached transactions.csv)
The purchase_1 to purchase_1 represent the
product_id
I have a separate list of products (see attached products.csv)
The
depivot is configured as so:

and yeilds exactly what I'd expect and creates a new
product_id row:

However, when I try to input the result of this unpivot to the
join operation, I'm getting a warning about the
product_uid missing in the de-pivot output.

When I execute the process, the join seems to work

Shall I just disregard this warning message?
For reference, in attachment is the entire process
cheers
Jan