Follow One Request to Hardware
The same request, but nobody stops at the handler. This walk crosses out of Backend Engineering into Operating Systems and then into Computer Architecture, because the layers below yours are where the numbers eventually come from.
You do not need this daily. Most backend work is correctly reasoned about at the top two steps. You need it on the day the profiler says your code is fast, the database says the query is fast, and the request is still slow — at which point the answer is somewhere in between, in a layer that no dashboard in your service owns. Each step names the domain that teaches it properly.
- What this actually costs
Everything below is what "call the database" actually costs. You do not need it daily — you need it when the numbers stop making sense.
What can go wrong here- — Logic errors
- — Unbounded work per request