A Cache Is a Second, Older Copy, So Caching Anything Is Agreeing to Be Wrong for a While
Everything else in this sub-domain is a mechanism, and a mechanism chosen without a stated tolerance produces a system nobody can reason about afterwards. This node rests only on the entry floor - the database holds the truth and reading it costs something - and the TTL, invalidation, write-shape and per-viewer-key nodes are all answers to the question it forces. It is also the node that lets a learner decide not to cache a value at all, which is a real and frequently correct outcome.
Cache Consistency and Invalidation Strategies in System Design
Cache architecture theory centers on the fundamental tradeoff between consistency, latency, and staleness, requiring engineers to choose write strategies (such as write-behind) and invalidation strat…