How can a cache be implemented on the backend? What are the methods?

Caching on the backend can be implemented in several ways:

1. In-memory application cache — storing data in RAM (e.g., using dictionaries, LRU caches). Fast, but limited by server resources and not suitable for scalable systems.

2. External cache systems — Redis, Memcached. Allow centralized cache storage, providing high access speed and scalability.

3. HTTP caching — using Cache-Control headers, ETag for caching responses at the HTTP level.

4. Database-level caching — for example, Materialized Views, indexes, or built-in caching mechanisms.

5. CDN caching — for static content and API responses.

Example of using Redis to cache query results in Python:

import redis

cache = redis.Redis(host='localhost', port=6379)

key = 'user_123_profile'
cached_data = cache.get(key)
if cached_data:
    profile = cached_data
else:
    profile = get_profile_from_db(123)  # function to fetch from DB
    cache.set(key, profile, ex=3600)  # cache for an hour