This week in caching: Redis object cache, the parts that bite
For WP and app devs who added Redis and assumed it just works.
— alloptions is your silent memory hog — Till Krüss's notes on how a bloated wp_options autoload row gets cached as one giant key, evicted constantly, thrashing your hit rate.
— maxmemory-policy matters more than maxmemory — allkeys-lru vs noeviction is the difference between graceful degradation and write errors at capacity.
— persistent connections or you pay TCP every request — PhpRedis vs Predis: the C extension wins on high-traffic sites, measurably.
Bookmark: Till Krüss's Object Cache Pro docs — even the free reading explains group-flushing better than anywhere else.