[lance_klusener]

"walk through a zero downtime migration plan from before and after we add a feature."

How does one approach this?

[stack_underflow]

If you're asking about specific examples, this book covers a lot of common patterns I've seen over the years; maybe a good starting point:

https://martinfowler.com/books/refactoringDatabases.html https://databaserefactoring.com/