At scale there are no rollbacks and no cut-overs. Your software only moves forward. aside: This email is adapted from a book chapter I spent the last 3 weeks writing. It's a complex idea that took 10 years to grok. I tried squeezing it into a digestible length. Would love to hear your thoughts. Data lives forever Data is the biggest reason software only moves forward. Once you save state, your code will need to understand that state forever. This is double true for state that leaves your system ...