Redis-- Memory Management

A memory management:

command	effect
expire key seconds	Set a timeout timestamp in seconds
ttl key	See timeout, -1 means no timeout, -2 represent has expired
persist key	Persistence Key , cancel timeout

　　1, redis-cli:

　　　　

　　2, spring operation:

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:redis.xml")
public class RedisTest {
    @Autowired
    private RedisTemplate redisTemplate;

    @Test
    public void testExpireTime() {
        redisTemplate.execute(new SessionCallback() {
            public Object execute(RedisOperations operations) throws DataAccessException {

                ValueOperations ops = operations.opsForValue();
                ops.set("myhome", "China");
                operations.expire("myhome", 100, TimeUnit.SECONDS);
                Long time = operations.getExpire("myhome");
                System.out.println(time);
                operations.persist("myhome");
                Long time1 = operations.getExpire("myhome");
                System.out.println(time1);

                return null;
            }
        });
    }
}

Second, memory recovery strategy:

　　1, automatic recovery after a timeout is not, only the mark key has expired;

　　2, inert recycling: get command has timed recovery keys;

　　3, redis.conf: configuration hz 1 ~ 100;

　　　　To recover // hz frequency: recommended configuration 10;　　

　　　　

　　4, accurate recovery: maxmemory-samples 1 ~ 10

　　　　// 10: The most delicate, the slowest; 1: the least accurate and fastest;

　　　　

　　5, maxmemory: maximum memory configuration, the memory key exceeds this maximum, the LRU algorithm directly recycled;

　　5, recovery algorithm:

　　　　maxmemory-policy: noeviction // default

　　　　

Volatile-lru	Phase out the use of least recently used strategy, Redis will recover those time-out value pairs
Allkeys-lru	Redis will have all the key-value pairs, using the least recently used strategy be eliminated
Volatile-random	A randomized phase-out policy removes the timeout value pairs
Allkeys-random	A randomized phase-out strategy to remove all key-value pairs
Volatile-ttl	Delete the shortest survival time using key-value pairs strategy
Noeviction	Not out of any key-value pairs, when the memory is full, only supports reading and writing are not supported

　　// redis default algorithm is none, but will get the use of inert recycling;

　　// recommended Volatile-lru and Allkeys-lru algorithm;