Architecture & practice·Making and recording decisions
someone asked whether this needed a written decision, and the answer was whether it would be expensive to change later.
Architectural significance
The test for which decisions deserve process. A decision is architecturally significant if reversing it later would be costly — it crosses team boundaries, affects a public interface, shapes the data model, or picks a technology the organisation will have to operate. Everything else should be made by whoever is doing the work, and the failure to draw this line is why some teams write documents for library choices and none for the schema.