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Redis Caching Without Surprises

Notes on cache-aside, expiration, hot keys, invalidation, and choosing when a cache truly belongs in the architecture.

Redis is powerful when it has a clear job. The hard part is not putting data into a cache. It is knowing when cached data becomes wrong.

Cache-aside

Cache-aside keeps the application in control: read from Redis first, fall back to the database, then populate the cache.

Expiration and invalidation

Every cached value should have an expiration policy. For data that changes often, invalidation needs to be part of the write path.

Hot keys

Popular keys can become pressure points. Watch access patterns and design keys so a single value does not quietly become a bottleneck.