redis-expert

Redis Expert

Installation

# Ubuntu
apt install redis-server -y
systemctl enable redis-server

# Docker
docker run -d --name redis -p 6379:6379 redis:alpine

Basic Commands

redis-cli

Strings

SET key "value" GET key SETEX key 3600 "value" # With TTL (1 hour) TTL key # Check TTL

Hash (objects)

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

Lists

LPUSH queue "task1" RPOP queue

Sets

SADD tags "node" "redis" SMEMBERS tags

Sorted Sets

ZADD leaderboard 100 "player1" ZRANGE leaderboard 0 -1 WITHSCORES

## Node.js Integration

```typescript
import { createClient } from 'redis';

const redis = createClient({ url: 'redis://localhost:6379' });
await redis.connect();

// Cache pattern
async function getUser(id: string) {
  const cached = await redis.get(`user:${id}`);
  if (cached) return JSON.parse(cached);
  
  const user = await db.user.findUnique({ where: { id } });
  await redis.setEx(`user:${id}`, 3600, JSON.stringify(user));
  return user;
}

// Invalidate
await redis.del(`user:${id}`);

Caching Strategies

Strategy	Use Case	Implementation
Cache-Aside	Read-heavy	Check cache → Miss → Load DB → Store cache
Write-Through	Consistency	Write DB → Write cache
Write-Behind	Write-heavy	Write cache → Async write DB
TTL	General	Set expiration time

Common Patterns

// Rate limiting
async function rateLimit(ip: string, limit = 100) {
  const key = `rate:${ip}`;
  const count = await redis.incr(key);
  if (count === 1) await redis.expire(key, 60);
  return count <= limit;
}

// Session storage
app.use(session({
  store: new RedisStore({ client: redis }),
  secret: 'secret',
  resave: false,
  saveUninitialized: false
}));

// Pub/Sub
await redis.subscribe('channel', (message) => {
  console.log('Received:', message);
});
await redis.publish('channel', 'Hello!');