incremental model fails on second run

The problem I’m having

I use a dbt model to transform data in a postgres db. When I run an incremental model more than once it runs into an error complaining about a missing column. The error occurs only when I define a unique key.

The context of why I’m trying to do this

I use an incremental model to append new data to a table. In my understanding the dbt model has to be executed every time new data is loaded to the db.

Some example code or error messages

This is my model:

{{ config(
  unique_key = ‘Date1, product’
) }}

from {{ source('sc’,’table_raw’) }} mu
{% if is_incremental() %}
  where mu."Date1" > (select max("Date1") from {{ this }})
{% endif %}
order by product, mu."Date1"

This is the translated error :

ERROR: Column »date1« does not exist
LINE 8: select (Date1, product)
HINT: Perhaps the intention is to refer to column »units__dbt_tmp220418107752.Date1« or to the column »units.Date1«.