How to Optimize Laravel Eloquent Queries: Fix N+1 Problem

The Problem

// This causes N+1 queries!
$posts = Post::all();

foreach ($posts as $post) {
    echo $post->author->name; // Query for EACH post
}

100 posts = 101 queries!

Solution: Eager Loading

Basic Eager Loading

// Only 2 queries now!
$posts = Post::with('author')->get();

foreach ($posts as $post) {
    echo $post->author->name; // No extra query
}

Multiple Relationships

$posts = Post::with(['author', 'comments', 'tags'])->get();

Nested Relationships

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

Conditional Eager Loading

$posts = Post::with(['comments' => function ($query) {
    $query->where('approved', true)
          ->orderBy('created_at', 'desc');
}])->get();

Detecting N+1 Problems

Method 1: Laravel Debugbar

composer require barryvdh/laravel-debugbar --dev

Method 2: Prevent Lazy Loading

// AppServiceProvider.php
public function boot()
{
    Model::preventLazyLoading(!app()->isProduction());
}

Method 3: Query Log

DB::enableQueryLog();
// Your code here
dd(DB::getQueryLog());

Other Optimization Tips

// Select only needed columns
Post::with('author:id,name')->select('id', 'title', 'author_id')->get();

// Use lazy eager loading when needed
$posts = Post::all();
if ($needAuthors) {
    $posts->load('author');
}

// Count without loading
$post->comments()->count();
// Instead of
$post->comments->count();