What caching does Laravel provide?

Question

Accepted Answer

Laravel offers a unified, expressive **caching system** with multiple backends (Redis, Memcached, file, database, array) behind a single API. Caching stores expensive results so they don't have to be recomputed — one of the highest-impact performance optimizations.

## The cache API

```php
use Illuminate\Support\Facades\Cache;

Cache::put('key', $value, 3600);          // store for 1 hour (seconds)
Cache::get('key');                         // retrieve (null if missing)
Cache::get('key', 'default');              // with a default
Cache::has('key');
Cache::forget('key');                      // delete (invalidate)
Cache::forever('key', $value);             // store with no expiry
```

## remember() — the get-or-compute pattern (most useful)

```php
// if cached, return it; otherwise run the closure, cache the result, and return it
$users = Cache::remember('active_users', 3600, function () {
    return User::where('active', true)->get();   // expensive query — cached for 1 hour
});
```

`Cache::remember()` is the elegant, common pattern: it returns the cached value if present, or computes it (running the closure), caches it, and returns it — in one call. Perfect for caching expensive query results.

## Configurable backends (Redis for production)

```text
config/cache.php → choose the driver:
  redis     → fast, SHARED across servers (production standard for multi-server apps)
  memcached → fast, shared
  file/database → simpler, for smaller/single-server setups
  array     → in-memory, for testing
The SAME Cache API works regardless of backend → easy to switch.
```

The unified API means the same code works with any backend — and **Redis** is the standard for production (a shared cache across multiple server instances).

## Cache invalidation (the hard part)

```php
// when data changes, clear the affected cache or it serves stale data
public function updateUser($user, $data) {
    $user->update($data);
    Cache::forget('active_users');     // INVALIDATE so the next read recomputes
}
// strategies: TTL (accept brief staleness), explicit forget on writes, cache tags
Cache::tags(['users'])->flush();        // tagged invalidation (Redis/Memcached)
```

## Why it matters

Caching is one of the highest-impact performance optimizations for Laravel applications, and the framework's unified, expressive caching system makes it accessible — so understanding it is valuable for building fast, scalable applications.

The core value is avoiding repeated expensive work: caching the results of slow database queries, complex computations, or external API calls means subsequent requests are served quickly, dramatically reducing latency and load.

Laravel's caching is elegant, especially the **`Cache::remember()` get-or-compute pattern** (returning cached data if present, or computing, caching, and returning it in one clean call — ideal for caching query results), and its **unified API across backends** means the same code works with any driver.

Knowing to use **Redis** for production (a shared cache across multiple server instances — important since simpler per-server caches aren't shared when scaling horizontally) is an important architectural point.

Equally important is understanding caching's central difficulty — **invalidation** (clearing or refreshing cached data when the underlying data changes, via TTLs, explicit `forget` on writes, or cache tags, to avoid serving stale data) — since getting this wrong is the classic caching failure that shows users outdated information.

Understanding Laravel's caching system — the API, the `remember` pattern, backend selection (Redis for scale), and especially invalidation strategies — is important senior-level knowledge for building performant, scalable Laravel applications, since caching delivers major performance gains but requires careful invalidation to remain correct.