Data consistency is overrated
I think there are two different kinds of consistency, and it&#x27;s important to not conflate them.<p>There&#x27;s consistency that&#x27;s <i>internal</i> to a system. Do all of the foreign keys line up correctly? Have I lost any data that was provided to me? Here, we can aspire to be 100% correct. I don&#x27;t think the examples in this article conflict with that.<p>Then there&#x27;s consistency that&#x27;s <i>external</i> to a system. This can be between this system and other systems, or between this system and reality. Did the operator enter the correct data for this item? Did the external system change and fail to tell me? Here there is no way to be 100% correct using only the tools that are inside the system. You need external audits, reality checks, periodic reconciliation.<p>Critically, all of the author&#x27;s examples are about external consistency (accounting matching reality; inter-system communication), but their conclusion seems to be that because external consistency can&#x27;t be fully achieved, we should be OK to abandon internal consistency within single systems. I think that&#x27;s too strong a conclusion.