在rethinkdb表中添加新列？

I am converting an excel sheet to an array of JSON objects, mapping the data to column names, and then inserting them into RethinkDB. The problem is that I then need to later on append those docs in the db with data that is being calculated elsewhere. This means adding new columns to the docs that are already stored in the database, then inserting the data into those columns. Is there any way to do this? I am converting an excel sheet to an array of J