Code Quiz

Redis Cache-Aside Serialization Bug

A cache-aside function using Redis stores user objects but retrieves corrupted data on cache hits.

Codejavascript

// node-redis v4 client
async function getUser(id) {
  const key = `user:${id}`;

  const cached = await client.get(key);
  if (cached) {
    return cached; // cache hit
  }

  const user = await db.getUser(id); // { id, name, email }
  await client.set(key, user, { EX: 3600 });

  return user;
}

What is the bug in this Redis caching code?

Next →Redis Distributed Cache Consistency