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PHP Academy · Lesson

Cache Invalidation Patterns

Apply cache-aside, write-through, and TTL-based invalidation strategies.

The Hard Problem

"There are only two hard things in Computer Science: cache invalidation and naming things." — Phil Karlton. Knowing when and how to invalidate cached data is critical.

TTL-Based Expiry (Passive)

The simplest strategy: set a TTL and accept that the cache may serve stale data for up to that duration. Works when slight staleness is acceptable.

<?php
Cache::put("user:1", $user, 300); // expires in 5 minutes automatically

All lessons in this course

  1. Why Caching Matters in PHP
  2. Redis as a PHP Cache Backend
  3. Memcached for Session and Object Caching
  4. Cache Invalidation Patterns
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