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.claude/skills/laravel-best-practices/rules/db-performance.md

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+# Database Performance Best Practices
+
+## Always Eager Load Relationships
+
+Lazy loading causes N+1 query problems — one query per loop iteration. Always use `with()` to load relationships upfront.
+
+Incorrect (N+1 — executes 1 + N queries):
+```php
+$posts = Post::all();
+foreach ($posts as $post) {
+    echo $post->author->name;
+}
+```
+
+Correct (2 queries total):
+```php
+$posts = Post::with('author')->get();
+foreach ($posts as $post) {
+    echo $post->author->name;
+}
+```
+
+Constrain eager loads to select only needed columns (always include the foreign key):
+
+```php
+$users = User::with(['posts' => function ($query) {
+    $query->select('id', 'user_id', 'title')
+          ->where('published', true)
+          ->latest()
+          ->limit(10);
+}])->get();
+```
+
+## Prevent Lazy Loading in Development
+
+Enable this in `AppServiceProvider::boot()` to catch N+1 issues during development.
+
+```php
+public function boot(): void
+{
+    Model::preventLazyLoading(! app()->isProduction());
+}
+```
+
+Throws `LazyLoadingViolationException` when a relationship is accessed without being eager-loaded.
+
+## Select Only Needed Columns
+
+Avoid `SELECT *` — especially when tables have large text or JSON columns.
+
+Incorrect:
+```php
+$posts = Post::with('author')->get();
+```
+
+Correct:
+```php
+$posts = Post::select('id', 'title', 'user_id', 'created_at')
+    ->with(['author:id,name,avatar'])
+    ->get();
+```
+
+When selecting columns on eager-loaded relationships, always include the foreign key column or the relationship won't match.
+
+## Chunk Large Datasets
+
+Never load thousands of records at once. Use chunking for batch processing.
+
+Incorrect:
+```php
+$users = User::all();
+foreach ($users as $user) {
+    $user->notify(new WeeklyDigest);
+}
+```
+
+Correct:
+```php
+User::where('subscribed', true)->chunk(200, function ($users) {
+    foreach ($users as $user) {
+        $user->notify(new WeeklyDigest);
+    }
+});
+```
+
+Use `chunkById()` when modifying records during iteration — standard `chunk()` uses OFFSET which shifts when rows change:
+
+```php
+User::where('active', false)->chunkById(200, function ($users) {
+    $users->each->delete();
+});
+```
+
+## Add Database Indexes
+
+Index columns that appear in `WHERE`, `ORDER BY`, `JOIN`, and `GROUP BY` clauses.
+
+Incorrect:
+```php
+Schema::create('orders', function (Blueprint $table) {
+    $table->id();
+    $table->foreignId('user_id')->constrained();
+    $table->string('status');
+    $table->timestamps();
+});
+```
+
+Correct:
+```php
+Schema::create('orders', function (Blueprint $table) {
+    $table->id();
+    $table->foreignId('user_id')->index()->constrained();
+    $table->string('status')->index();
+    $table->timestamps();
+    $table->index(['status', 'created_at']);
+});
+```
+
+Add composite indexes for common query patterns (e.g., `WHERE status = ? ORDER BY created_at`).
+
+## Use `withCount()` for Counting Relations
+
+Never load entire collections just to count them.
+
+Incorrect:
+```php
+$posts = Post::all();
+foreach ($posts as $post) {
+    echo $post->comments->count();
+}
+```
+
+Correct:
+```php
+$posts = Post::withCount('comments')->get();
+foreach ($posts as $post) {
+    echo $post->comments_count;
+}
+```
+
+Conditional counting:
+
+```php
+$posts = Post::withCount([
+    'comments',
+    'comments as approved_comments_count' => function ($query) {
+        $query->where('approved', true);
+    },
+])->get();
+```
+
+## Use `cursor()` for Memory-Efficient Iteration
+
+For read-only iteration over large result sets, `cursor()` loads one record at a time via a PHP generator.
+
+Incorrect:
+```php
+$users = User::where('active', true)->get();
+```
+
+Correct:
+```php
+foreach (User::where('active', true)->cursor() as $user) {
+    ProcessUser::dispatch($user->id);
+}
+```
+
+Use `cursor()` for read-only iteration. Use `chunk()` / `chunkById()` when modifying records.
+
+## No Queries in Blade Templates
+
+Never execute queries in Blade templates. Pass data from controllers.
+
+Incorrect:
+```blade
+@foreach (User::all() as $user)
+    {{ $user->profile->name }}
+@endforeach
+```
+
+Correct:
+```php
+// Controller
+$users = User::with('profile')->get();
+return view('users.index', compact('users'));
+```
+
+```blade
+@foreach ($users as $user)
+    {{ $user->profile->name }}
+@endforeach
+```