将具有非唯一列的activerecord导入到postgres中

I am trying to use activerecord-import to import data and I ran into an issue. In case the row already exists it needs to be updated else it needs to be created. The unique rows in the table are defined by a combination of two columns where each column value might not be unique in the table. How would I go about using the on_duplicate_key_update's conflict_target since the columns are not unique columns.I am trying to use activerecord-import to impor