zero-downtime, rolling Database Schema Migrations at github

Shlomi Noach walks us through the history and details of github's approach to their database schema migrations up to and including details of their current zero-touch automated method that uses github actions.  Like many of us they started with Ruby on Rails because it automated schema migrations for them.  The current method is interesting but forgives a few bad practices of their developers, including not testing compatibility of clients and servers with disparate schema versions.  Still worth a read though.