Why should you care?

Repeated account profile reads hammer Mongo; cache absorbs 90% read load.

See it live — copy this example

Paste into your MeanVerse project (Angular + Express + MongoDB), then run with ng serve / node / mongosh as noted.

import { createClient } from 'redis';

const redis = createClient({ url: process.env.REDIS_URL });
await redis.connect();

async function getAccountCached(id: string) {
  const key = `account:${id}`;
  const hit = await redis.get(key);
  if (hit) return JSON.parse(hit);
  const doc = await Account.findById(id).lean();
  if (doc) await redis.setEx(key, 60, JSON.stringify(doc));
  return doc;
}

// invalidate on update
await Account.updateOne({ _id: id }, { $set: { name } });
await redis.del(`account:${id}`);

What happened?

• Cache-aside: read Redis first, on miss load Mongo and setEx TTL 60s.
• del on update prevents stale name showing.

Practice next

1. Cache read-heavy stable data with short TTL.
2. Invalidate or update cache on writes.
3. Use Redis for rate limit and session stores.
4. Add cache stampede lock with SET NX.
5. Cache GraphQL resolver results keyed by query hash.

Remember

Redis = in-memory cache and coordination. Cache-aside + invalidation pattern common. TTL bounds staleness risk.

Product catalog API

E-commerce PDP hits Mongo 5k req/s during sale.

Outcome: Redis cache 94% hit rate; Mongo CPU drops 70%.