Eager loading and performance

 

Interview answer

Eager loading retrieves relationships upfront to avoid repeated database queries.

$users = User::with('orders')->get();

Instead of:

$users = User::all();

foreach ($users as $user) {
    echo $user->orders->count();
}

The second version can produce an N+1 problem.

Nested eager loading:

$orders = Order::with([
    'user',
    'items.product'
])->get();

Constrained eager loading:

$users = User::with([
    'orders' => function ($query) {
        $query->where('status', 'paid');
    }
])->get();

Scenario

On a page displaying 100 users and their orders, eager loading can reduce hundreds of relationship queries to a small number of queries.