Eager Loading

Also Known As

TL;DR

Explanation

Eager loading fetches all needed data in one query (or a small fixed number), whereas lazy loading issues additional queries when related data is accessed. In PHP ORMs, eager loading is typically triggered with with() or join() methods. It is the remedy for N+1 query problems: instead of loading 100 posts and then issuing 100 separate queries for each post's author, eager loading fetches all authors in one additional query. The trade-off is fetching data that may not be needed — profile queries to find the right balance.

Common Misconception

Why It Matters

Common Mistakes

• Eager loading every relationship by default — loading unused related data wastes memory and query time.
• Not checking that eager loading is actually used — an eager-loaded relationship that's never accessed is pure waste.
• Eager loading deeply nested relationships unnecessarily — each level multiplies the data fetched.
• Using eager loading in APIs where the client only needs IDs — load just what the response requires.

Code Examples

// Triggers N+1 queries — one per order
\$orders = Order::all();
foreach (\$orders as \$order) {
    echo \$order->user->name; // each access fires a new query
}

// Eager load — single JOIN query fetches all related records
\$orders = Order::with('user')->get();
foreach (\$orders as \$order) {
    echo \$order->user->name; // no additional query
}

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

// Constrained eager loading:
\$users = User::with(['orders' => fn(\$q) => \$q->where('status', 'paid')->latest()])->get();

// Check for N+1 in development:
// Laravel Debugbar or:
DB::listen(fn(\$q) => logger(\$q->sql)); // logs every query

References

• ↗ https://en.wikipedia.org/wiki/Eager_loading

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