Masalah N+1 Query

Ini adalah masalah performa paling umum saat pakai ORM.

// ❌ BURUK — N+1 Problem!
$posts = Post::all(); // 1 query

foreach ($posts as $post) {
    echo $post->user->name; // 1 query PER POST!
}

// Jika ada 100 post → 101 queries! 🔥

Solusi: Eager Loading dengan with()

// ✅ BAGUS — hanya 2 queries
$posts = Post::with('user')->get();

foreach ($posts as $post) {
    echo $post->user->name; // Data sudah di-load sebelumnya
}

// Query yang dijalankan:
// SELECT * FROM posts
// SELECT * FROM users WHERE id IN (1, 2, 3, ...)

Eager Loading Bersarang (Nested)

// Load relasi bertingkat
$posts = Post::with('user.profile')->get();

// Load banyak relasi sekaligus
$posts = Post::with(['user', 'tags', 'comments'])->get();

// Load relasi dengan kondisi (Constrained Eager Loading)
$posts = Post::with([
    'comments' => function ($query) {
        $query->where('approved', true)
              ->latest()
              ->limit(5);
    }
])->get();

withCount() — Hitung Relasi Tanpa Load Data

// Hitung jumlah comments tanpa load semua comment
$posts = Post::withCount('comments')->get();

foreach ($posts as $post) {
    echo $post->comments_count; // properti otomatis tersedia
}

// Hitung dengan kondisi
$posts = Post::withCount([
    'comments',
    'comments as approved_comments_count' => function ($query) {
        $query->where('approved', true);
    }
])->get();

load() — Lazy Eager Loading

Berguna jika model sudah di-load dan baru perlu relasi di kondisi tertentu:

$posts = Post::all();

// Kondisi tertentu baru load relasi
if ($needsUserData) {
    $posts->load('user');
}

// Load banyak relasi
$posts->load(['user', 'tags']);

loadMissing() — Load Hanya yang Belum Ada

$posts = Post::with('user')->get();

// Load tags hanya jika belum di-load
$posts->loadMissing('tags');

Deteksi N+1 dengan Laravel Debugbar

composer require barryvdh/laravel-debugbar --dev

Atau gunakan DB::listen untuk log query:

// Di AppServiceProvider::boot()
if (app()->isLocal()) {
    \DB::listen(function ($query) {
        logger($query->sql, $query->bindings);
    });
}

Mencegah Lazy Loading di Production

// Di AppServiceProvider::boot()
use Illuminate\Database\Eloquent\Model;

Model::preventLazyLoading(! app()->isProduction());
// Akan throw exception jika ada lazy load di development

Perbandingan Performa

// Skenario: 1000 posts, tampilkan nama user

// ❌ Tanpa Eager Loading
// → 1001 queries, ~500ms

$posts = Post::all();
foreach ($posts as $post) {
    echo $post->user->name;
}

// ✅ Dengan Eager Loading
// → 2 queries, ~20ms

$posts = Post::with('user')->get();
foreach ($posts as $post) {
    echo $post->user->name;
}

Ringkasan Episode 6