Why does Redis need so much memory? Can I get away with less?

Detailed Answer

Redis is an in-memory store, so memory is the constraint. The first thing to check: are you storing values you don't need? Common offenders are unbounded session lists, message queues without a TTL, and large JSON blobs you could store elsewhere. The next lever is `maxmemory-policy`. If you don't set it, Redis will return errors once it hits the limit. The common choices are `allkeys-lru` (evict least-recently-used keys) and `volatile-lru` (only evict keys with a TTL set). For a pure cache, `allkeys-lru` is usually right. If memory is genuinely the bottleneck and the data is hot, the real answer is: pay for more memory, or shard across multiple Redis nodes. Redis Cluster gives you sharding but the client library needs to be cluster-aware.