Tag
The honest three algorithms, layered key design including the abuse limits everyone forgets (per victim, not per attacker), the 429 contract, and operational rules — fail open, shadow mode, degrade before deny.
The minimal correct lock and the four bugs hiding in simpler versions, fencing tokens for the expiry race, Redlock in two fair paragraphs, and the lock-free designs that beat locking entirely.
Organized by the incident it prevents: maxmemory and eviction policies, AOF vs RDB persistence blends, Sentinel vs Cluster reality, the fork-memory trap and the five-number dashboard.
The 95% of Redis teams never open: atomic counters, rate limiters, sorted-set schedulers, pub/sub vs streams (one of them forgets!), queue pragmatics and the eviction-policy line that forces two instances.
Cache-aside with the two mandatory upgrades — TTL jitter and stampede protection — plus version-stamped invalidation, the after-commit trap, and the three metrics that keep a cache honest.
