Redis Caching: Speed Up Your Applications

Redis is an in-memory data structure store used as a database, cache, and message broker. It supports strings, hashes, lists, sets, sorted sets, and more.

## Why Redis?

- Extremely fast (in-memory)
- Rich data types
- Persistence options
- Pub/Sub messaging
- Atomic operations

## Basic Commands

```bash
# Strings
SET user:1 "John"
GET user:1

# Expiration
SET session:abc "data" EX 3600

# Hashes
HSET user:1 name "John" email "john@example.com"
HGET user:1 name

# Lists
LPUSH queue "task1"
RPOP queue

# Sets
SADD tags "redis" "cache"
SMEMBERS tags
```

## Caching Patterns

### Cache-Aside

```javascript
async function getUser(id) {
 let user = await redis.get(`user:${id}`);
 if (!user) {
   user = await db.getUser(id);
   await redis.set(`user:${id}`, JSON.stringify(user), 'EX', 3600);
 }
 return JSON.parse(user);
}
```

### Write-Through

```javascript
async function updateUser(user) {
 await db.updateUser(user);
 await redis.set(`user:${user.id}`, JSON.stringify(user), 'EX', 3600);
}
```

## Best Practices

1. Set expiration on all cached data
2. Use consistent key naming
3. Handle cache misses gracefully
4. Monitor memory usage
5. Use pipelining for bulk operations

## Conclusion

Redis dramatically improves application performance. Use it for caching, sessions, leaderboards, and real-time features.