Working with Redis

What is Redis?

Redis is an in-memory data store. Super fast because data lives in RAM.

Use cases:

• Caching
• Sessions
• Real-time analytics
• Pub/Sub messaging
• Rate limiting

Setup

npm install redis

const redis = require('redis');

const client = redis.createClient({
  host: 'localhost',
  port: 6379
});

await client.connect();

Basic Operations

await client.set('key', 'value');

const value = await client.get('key');

await client.setEx('key', 3600, 'value');

await client.del('key');

const exists = await client.exists('key');

await client.incr('counter');

Caching Pattern

async function getUser(id) {
  const cacheKey = `user:${id}`;
  
  const cached = await client.get(cacheKey);
  if (cached) {
    return JSON.parse(cached);
  }
  
  const user = await User.findById(id);
  
  await client.setEx(cacheKey, 3600, JSON.stringify(user));
  
  return user;
}

Lists

await client.rPush('queue', 'task1');
await client.rPush('queue', 'task2');

const task = await client.lPop('queue');

const length = await client.lLen('queue');

Sets

await client.sAdd('tags', 'nodejs');
await client.sAdd('tags', 'redis');

const isMember = await client.sIsMember('tags', 'nodejs');

const members = await client.sMembers('tags');

Hashes

await client.hSet('user:123', 'name', 'John');
await client.hSet('user:123', 'email', 'john@example.com');

const name = await client.hGet('user:123', 'name');

const user = await client.hGetAll('user:123');

Key Takeaway

Redis is fast in-memory storage. Use for caching, sessions, queues. Data structures: strings, lists, sets, hashes. Set expiration to save memory.