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

```bash npm install redis ```

```javascript const redis = require('redis');

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

await client.connect(); ```

Basic Operations

```javascript 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

```javascript 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

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

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

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

Sets

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

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

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

Hashes

```javascript 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.