How to add a column to a very large table managed by Heroku Connect with minimal downtime
Heroku Connect provides the ability to add columns to a Mapping post-sync, however, if the underlying object contains a large number of rows the operation may take a long period of time to complete. Moreover, during this time no new changes will be synced. This document explains how to create a new Heroku Connect add-on and subsequently swap it for the existing add-on with the minimal amount of downtime for the Heroku app using the Heroku Connect add-on.