Redis: more than just caching

1. Queues

Redis is ideal for implementing simple task queues.

Usage: background jobs, event processing

Main commands:

• LPUSH— add to the queue

• RPOP/BLPOP— get from the queue

Example (Node.js + ioredis)

import Redis from 'ioredis';

const redis = new Redis();

// Producer (додає задачу)
async function addJob(data) {
  await redis.lpush('queue:emails', JSON.stringify(data));
}

// Worker (обробляє задачі)
async function worker() {
  while (true) {
    const res = await redis.brpop('queue:emails', 0);
    const job = JSON.parse(res[1]);

    console.log('Processing:', job);
  }
}

worker();

Pros:

• Simplicity

• Instant processing

Minus:

• No retry / ack (for more complex cases BullMQ is better)

2. Pub/Sub (Publish / Subscribe)

Redis allows you to implement a real-time messaging system.

Usage: chats, notifications, WebSocket

Example

// subscriber.js
const sub = new Redis();

sub.subscribe('chat');

sub.on('message', (channel, message) => {
  console.log(`New message: ${message}`);
});

// publisher.js
const pub = new Redis();

Feature:

• Messages are not stored (this is not a queue!)

3. Rate Limiting (request limitation)

One of the most popular cases is API protection.

Using:

• DDoS protection

• limiting user requests

Example (Fixed Window)

async function rateLimit(ip) {
  const key = `rate:${ip}`;
  
  const current = await redis.incr(key);

  if (current === 1) {
    await redis.expire(key, 60); // 60 сек
  }

  if (current > 100) {
    throw new Error('Too many requests');
  }
}

Alternative:

• Sliding window (more accurate control)

• Token bucket (for API)

4. User sessions

Redis is often used as session storage.

Using:

• authorization

• shopping cart

• temporary data

Example

// збереження сесії
await redis.set(
  `session:${sessionId}`,
  JSON.stringify({ userId: 123 }),
  'EX',
  3600
);

// отримання
const session = JSON.parse(
  await redis.get(`session:${sessionId}`)
);

Pros:

• quickly

• TTL "out of the box"

5. Geospatial data (Geo)

Redis has built-in support for geodata.

Using:

• search "near me"

• delivery

• cards

Teams:

• GEOADD

• GEORADIUS

• GEODIST

Example

// додаємо координати
await redis.geoadd('drivers', 30.5234, 50.4501, 'driver_1');

// шукаємо поруч (5 км)
const nearby = await redis.georadius(
  'drivers',
  30.5234,
  50.4501,
  5,
  'km'
);

console.log(nearby);

6. Counters and analytics

Redis is great for real-time metrics.

Using:

• page views

• cursing

• analytics

Example

await redis.incr('page:home:views');

Or with TTL:

await redis.incr('stats:today');
await redis.expire('stats:today', 86400);

7. Distributed Locks

For synchronization between services.

Using:

• avoiding race conditions

• cron jobs

Example

const lock = await redis.set('lock:job', '1', 'NX', 'EX', 10);

if (lock) {
  console.log('Lock acquired');
  // виконуємо задачу
}

Conclusion

Redis is not just a cache, but a powerful tool for building:

• highly loaded APIs

• asynchronous systems

• real-time applications

• geoservices

If you use Redis only for cache, you use ~20% of its capabilities.

When should you use Redis?

Yes:

• required speed (milliseconds)

• temporary or frequently changing data

• real-time logic

No:

• complex transactions

• long-term storage of critical data