spring-data-redis

Spring Data Redis - Quick Reference

Full Reference: See advanced.md for hash/list/set operations, sorted sets, @RedisHash repository pattern, pub/sub configuration, and distributed lock patterns.

Deep Knowledge: Use mcp__documentation__fetch_docs with technology: spring-data-redis for comprehensive documentation.

Dependencies

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<!-- For reactive -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis-reactive</artifactId>
</dependency>

Configuration

spring:
  data:
    redis:
      host: localhost
      port: 6379
      password: ${REDIS_PASSWORD:}
      database: 0
      timeout: 2000ms
      lettuce:
        pool:
          max-active: 8
          max-idle: 8
          min-idle: 2

  cache:
    type: redis
    redis:
      time-to-live: 3600000  # 1 hour
      cache-null-values: false
      key-prefix: "myapp:"

RedisTemplate Configuration

@Configuration
public class RedisConfig {

    @Bean
    public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory connectionFactory) {
        RedisTemplate<String, Object> template = new RedisTemplate<>();
        template.setConnectionFactory(connectionFactory);

        Jackson2JsonRedisSerializer<Object> jsonSerializer =
            new Jackson2JsonRedisSerializer<>(Object.class);

        template.setKeySerializer(new StringRedisSerializer());
        template.setHashKeySerializer(new StringRedisSerializer());
        template.setValueSerializer(jsonSerializer);
        template.setHashValueSerializer(jsonSerializer);

        template.afterPropertiesSet();
        return template;
    }
}

Basic String Operations

@Service
@RequiredArgsConstructor
public class RedisService {

    private final RedisTemplate<String, Object> redisTemplate;

    public void set(String key, Object value, Duration ttl) {
        redisTemplate.opsForValue().set(key, value, ttl);
    }

    public Object get(String key) {
        return redisTemplate.opsForValue().get(key);
    }

    public boolean setIfAbsent(String key, Object value, Duration ttl) {
        return Boolean.TRUE.equals(
            redisTemplate.opsForValue().setIfAbsent(key, value, ttl));
    }

    public Long increment(String key) {
        return redisTemplate.opsForValue().increment(key);
    }

    public void delete(String key) {
        redisTemplate.delete(key);
    }
}

Spring Cache Integration

@SpringBootApplication
@EnableCaching
public class Application { }

@Configuration
@EnableCaching
public class CacheConfig {

    @Bean
    public RedisCacheManager cacheManager(RedisConnectionFactory connectionFactory) {
        RedisCacheConfiguration defaultConfig = RedisCacheConfiguration.defaultCacheConfig()
            .entryTtl(Duration.ofMinutes(30))
            .disableCachingNullValues()
            .serializeKeysWith(RedisSerializationContext.SerializationPair
                .fromSerializer(new StringRedisSerializer()))
            .serializeValuesWith(RedisSerializationContext.SerializationPair
                .fromSerializer(new GenericJackson2JsonRedisSerializer()));

        Map<String, RedisCacheConfiguration> cacheConfigs = Map.of(
            "users", defaultConfig.entryTtl(Duration.ofHours(1)),
            "products", defaultConfig.entryTtl(Duration.ofMinutes(15))
        );

        return RedisCacheManager.builder(connectionFactory)
            .cacheDefaults(defaultConfig)
            .withInitialCacheConfigurations(cacheConfigs)
            .build();
    }
}

Cache Annotations

@Service
public class UserService {

    @Cacheable(value = "users", key = "#id")
    public User getUserById(Long id) {
        return userRepository.findById(id).orElse(null);
    }

    @CachePut(value = "users", key = "#user.id")
    public User updateUser(User user) {
        return userRepository.save(user);
    }

    @CacheEvict(value = "users", key = "#id")
    public void deleteUser(Long id) {
        userRepository.deleteById(id);
    }

    @CacheEvict(value = "users", allEntries = true)
    public void clearUserCache() { }
}

When NOT to Use This Skill

• Raw Redis commands - Use redis skill for low-level operations
• Non-Spring applications - Use Jedis or Lettuce directly
• Primary database - Redis is for caching, not primary storage
• Complex queries - Use SQL databases for complex queries

Anti-Patterns

Anti-Pattern	Problem	Solution
No TTL on cached data	Memory exhaustion	Always set expiration
Large objects in cache	Memory pressure	Keep values small
Cache stampede	Thundering herd	Use distributed locks
@Cacheable on void methods	No effect	Only cache return values
Caching mutable objects	Stale data	Cache immutable or clone
No connection pooling	Connection exhaustion	Configure Lettuce pool

Quick Troubleshooting

Problem	Diagnostic	Fix
Connection refused	Check Redis running	Start Redis, check host/port
Cache not working	Check @EnableCaching	Add annotation, verify AOP proxy
Serialization error	Check object type	Configure proper serializer
Memory issues	redis-cli INFO memory	Set maxmemory, eviction policy

Production Checklist

• Connection pool configured
• TTL set on all keys
• Serializers configured
• Cluster/Sentinel for HA
• Memory limits set
• Eviction policy configured
• Monitoring enabled
• Error handling for failures

Reference Documentation

• Spring Data Redis Reference