冷启动数据环境中，流程如下：
Start ->
FlushDB ->
LOAD Data from Oracle/MySQL ->
Insert Data into Redis ->
End
FlushDB这个时间点a，完成LOAD时间点b，完成Insert 时间点c。
也就是说在（c - a）这么长的时间内，用户是无法获取数据的，即数据空白期。
这是很影响用户体验的。
我们改善一下流程：
Start ->
Select DB-sub ->
FlushDB-sub ->
LOAD Data from Oracle/MySQL ->
Insert Data into Redis DB-sub ->
SwapDB main & sub ->
END
这样的话，我们只在最后一个swap的过程中会有一个数据空白期，但是swap执行速度极快，也就是说，空白期几乎没有。
用Springboot实现，则会使用到Redis的Select以及Swapdb
SELECT int SWAPDB int int
pom.xml：
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
配置类：
@Configuration
public class RedisConfig {
private final LettuceConnectionFactory factory;
public RedisConfig(LettuceConnectionFactory factory) {
this.factory = factory;
}
@Bean
public RedisTemplate<String, Object> redisTemplate() {
factory.setShareNativeConnection(false);
RedisTemplate<String, Object> redisTemplate = new RedisTemplate<>();
redisTemplate.setKeySerializer(new StringRedisSerializer());
redisTemplate.setHashKeySerializer(new StringRedisSerializer());
redisTemplate.setHashValueSerializer(new StringRedisSerializer());
redisTemplate.setValueSerializer(new StringRedisSerializer());
redisTemplate.setConnectionFactory(factory);
return redisTemplate;
}
@Bean
public HashOperations<String, String, Object> hashOperations(RedisTemplate<String, Object> redisTemplate) {
return redisTemplate.opsForHash();
}
@Bean
public ValueOperations<String, String> valueOperations(RedisTemplate<String, String> redisTemplate) {
return redisTemplate.opsForValue();
}
@Bean
public ListOperations<String, Object> listOperations(RedisTemplate<String, Object> redisTemplate) {
return redisTemplate.opsForList();
}
@Bean
public SetOperations<String, Object> setOperations(RedisTemplate<String, Object> redisTemplate) {
return redisTemplate.opsForSet();
}
@Bean
public ZSetOperations<String, Object> zSetOperations(RedisTemplate<String, Object> redisTemplate) {
return redisTemplate.opsForZSet();
}
}
功能类：
public boolean insert() {
stringRedisTemplate.executePipelined((RedisCallback<Object>) redisConnection -> {
StringRedisConnection stringRedisConn = (StringRedisConnection) redisConnection;
logger.info("[REDIS] Switching to DB[" + subDatabase + "]");
stringRedisConn.select(subDatabase);
stringRedisConn.flushDb();
/** insert */
stringRedisConn.set(key,value);
return null;
});
return true;
}
swapDB 只能用Jedis实现：
public void dbSwap() {
Jedis jedis = new Jedis(host, port);
jedis.auth(password);
logger.info("[REDIS] Swapping DB[" + database + "] and DB[" + subDatabase + "]");
jedis.swapDB(database, subDatabase);
}
注意一下，为了selectdb，在配置类中
factory.setShareNativeConnection(false);
不然会切换失败