Eloquent Caching: Main Things You Need To Know

When working with large datasets that are complex to get or rarely change, we can use caching to reduce the load on our database.

For this, we will use the Cache class

In the examples, we will try to optimize the database call that takes 10 000 records from it.

Caching basics

To cache the dataset, use the Cache::remember() function:

app/Http/Controllers/ProductsController.php:

use Illuminate\Support\Facades\Cache;
 
// ...
 
Cache::remember('KEY', TIME_IN_SECONDS, function () {
return Model::get(); // or any other eloquent query
});

Caching model results

For example, we will get all records from Product model and cache them for 60 minutes.

app/Http/Controllers/ProductsController.php:

use Illuminate\Support\Facades\Cache;
 
// ...
 
public function index()
{
$products = Cache::remember('products_list', 60 * 60, function () {
return Product::get();
});
 
return view('products', compact('products'));
}

This results in no database call: results are taken from the cache.

Caching more complex results

What if you want to cache by some condition, like by category?

Let's add a condition to our previous example: filter by category and cache those results for 60 minutes, while keeping the original list intact.

app/Http/Controllers/ProductsController.php:

use Illuminate\Support\Facades\Cache;
use Illuminate\Http\Request;
 
// ...
 
public function index(Request $request)
{
if ($request->has('category')) {
$products = Cache::remember('products_list_' . $request->input('category'), 60 * 60, function () use ($request) {
return Product::where('category', $request->input('category'))->get();
});
} else {
$products = Cache::remember('products_list', 60 * 60, function () {
return Product::get();
});
}
 
return view('products', compact('products'));
}

As you can see, our key name becomes 'products_list_' . $request->input('category').

This way we will have a different cache key for each category and avoid overriding our default list of products.

Removing cached results

To remove cached data, call a Cache::forget() function with the key to remove.

app/Http/Controllers/ProductsController.php:

use Illuminate\Support\Facades\Cache;
 
// ...
 
Cache::forget('products_list');

Removing cached results after retrieving the data

Sometimes, you know that data needs to be updated on the next user request. Then use pull to retrieve stored data and then clear it.

app/Http/Controllers/ProductsController.php:

use Illuminate\Support\Facades\Cache;
 
// ...
 
public function index()
{
$products = Cache::pull('products_list', 60 * 60, function () {
return Product::get();
});
 
return view('products', compact('products'));
}

Auto-Clear Cache on Model Changes

Keep in mind: caching is going to retrieve the latest version of a model from the cache, even if you update it in the database. So, if you want to update the cache, remove it manually or use model observers to do it for you.

As an example your code might look something like this:

app/Models/Product.php:

use Illuminate\Support\Facades\Cache;
 
// ...
 
protected static function boot()
{
parent::boot();
 
static::created(function () {
Cache::forget('products_list');
});
 
static::updated(function () {
Cache::forget('products_list');
});
}
avatar

Whit the model observer isnt it save to use caching all over the place? Data is always cached and if it gets changed or updated, it will be cleared again. Am I missing something?

avatar

Pretty much, yes. But still double-check everything :)

avatar

pretty good 👍

avatar

@povilas what do you suggest for scnario when we have big cahce (half of millions records) and one of record (row in table) gets updated, should we rebuild whole cache or pick that record and find it in cache and update it ? and if we rebuild it, it means we have to invalidate (forget) old data and add new data right ? like code snippt below.

        Cache::forget('campaigns_pool');
        Cache::rememberForever('campaigns_pool', function () {
            return Campaigns::get();
        });

but with spike or big volumen traffic we get multiple hits at same time and that time if we invalidate cahce and create new one, we loose few hits ! (means cache won't be available)

Whats your recomendation on updating same key with different data in cahce when its big data?

A- Rebuild Cache
B- cherry pick record, find it and replcae it in cahce. (how?)
C- i didn't get your question. (because i have't explained properly :P !)

Thank You

avatar

I would rephrase this question a bit. Yes, in your scenario you described, the only thing you can do is rebuild the cache, because you're getting ALL the data.

My question would be WHY you need ALL the data at once? Do you REALLY NEED all 500,000 records with all their fields in the memory?

Maybe you could divide them by specific categories or tags or somehow identify the differences and cache only those parts that you need, and then rebuild caches on those specific parts if the updated record belongs to them.

In caching, you can use tags with Redis: see the docs

avatar

500,000 records are just related to one single vertical in system. This is bidding system and we keep all bidding information in table and build cache with related information required for bidding. whenever there is an update for a single client or a single category for now we are rebuilding whole cache but i am thinking with redis7 we can find that speific record and just update it would be better !

but again lets say we read that record do some manipulations, and now we have to write it ... while we are writing and at same time if we do read on same key what would be redis behaviour ! and on big data i guess we have to do some profiling that which is more time consuming task either update or rebuild whole cahe for an average size data with know redis cluster size.

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