Sure, it works for a narrow use-case like a pure function that just queries and returns data. What about stored procedures/triggers that mutate data on insert/d

Sure, it works for a narrow use-case like a pure function that just queries and returns data. What about stored procedures/triggers that mutate data on insert/delete etc? With one-box, you can assign a specific set of customers/canaries to be served by the new 1-box and validate your results. If there is a problem you rollback and only your canary data was affected. It is just not very simple IMO.