This week in caching: Redis vs Memcached for object cache

This week in caching: Redis vs Memcached for object cache

The perennial pairing, decided by what you actually store:

— Memcached wins when your cache is flat key-value strings and you're memory-bound — its slab allocator and multithreaded model squeeze more values per GB and scales reads across cores.
— Redis wins the moment you need cache tags, sorted sets for leaderboards, or LRU/LFU eviction tuned per-key — Memcached only does basic LRU.
— The tiebreaker most people miss: Memcached evicts silently under memory pressure with zero persistence, so a flush mid-traffic-spike cold-starts everything. Redis can maxmemory-policy allkeys-lfu and survive a restart with RDB snapshots.

Rule of thumb: single-server WP/Magento → Redis (you'll want tags). Massive read-only string cache across a fleet → Memcached.

Bookmark: the Redis maxmemory-policy docs — the eviction policy choice matters more than the engine choice.