Jen is the developer character from Evolutionary Database Design. In that essay she implemented a database refactoring – splitting an inventory_code field into location_code, batch_number, and serial_number – as a routine user story, illustrating that DBAs and developers can collaborate, schemas can evolve in small increments, and migrations carry the change forward safely.

The series picks up with Jen twenty years later. The methodology she follows is the same one she followed in 2003. What's new is the substrate underneath her workflow: copy-on-write database branching, which makes the practices she has been reading about operationally real at production scale. Across the three parts of this series she is the same Jen at three scopes – her day (Part 1), her new playbook (Part 2), and her team (Part 3).

This is Part 1