@lchynn 我没仔细看 redis 检索的实现原理，但在 kv 应用场景，一般可以控制 key 的驱逐策略，比如可以用 noeviction 策略，拒绝新的写入，或者 LRU 把最老的 evict 掉

https://redis.io/docs/reference/eviction/

The exact behavior Redis follows when the maxmemory limit is reached is configured using the maxmemory-policy configuration directive.

The following policies are available:

noeviction: New values aren’t saved when memory limit is reached. When a database uses replication, this applies to the primary database
allkeys-lru: Keeps most recently used keys; removes least recently used (LRU) keys
allkeys-lfu: Keeps frequently used keys; removes least frequently used (LFU) keys
volatile-lru: Removes least recently used keys with the expire field set to true.
volatile-lfu: Removes least frequently used keys with the expire field set to true.
allkeys-random: Randomly removes keys to make space for the new data added.
volatile-random: Randomly removes keys with expire field set to true.
volatile-ttl: Removes keys with expire field set to true and the shortest remaining time-to-live (TTL) value.