Assembler Upsert Date Column

Hi. I need to take a snapshot of today's data in order to compare it with tomorrow's data once it will be available. The problem is that the SQL dataflow and Magic ETL only can use Replace method. I need to find a way how to append the data each day to the already existing historical table.

I created Assembler and I chose Assembler Type as Upsert. I got an error message. Please see below the setup and error message.