Redis expiration Policy, redis expired

Redis expiration Policy, redis expired

I. redis keys have six expiration policies

1. noeviction: Once the memory is full, an error is returned.

2. allkeys-lru: Perform LRU on all keys

3. volatile-lru: Only LRU is performed on expired keys (default)

4. allkeys-random: Randomly removes a key.

5. volatile-random: Randomly removes an expired key.

6. volatile-ttl: Delete the expired key

According to the official website, the LRU used by redis is not a real LRU algorithm, and the accuracy is not high. LRU of redis3.0 maintains a candidate pool, which improves performance.

Ii. Set and view memory and expiration policies

1. Set the memory size of the Instance (-h $ host is not required for local execution, and the Unit is B)

Redis-cli-h $ host-p $ port config set maxmemory 1024

2. Obtain the memory size of the instance.

Redis-cli-h $ host-p $ port config get maxmemory

3. Set an expiration Policy

Redis-cli-h $ host-p $ port config set maxmemory-policy volatile-lru

4. view the expiration Policy

Redis-cli-h $ host-p $ port config get maxmemory-policy

Note: volatile-lru has been tested. If a key with an expiration time is set, LRU is executed and can be inserted. If no key with an expiration time is set, an error is returned.