Multiple groupBy on Laravel Collection
Stefan Bogdanescu
Founder & Senior Architect · 2026-06-29
# Mastering Multiple GroupBy on Laravel Collections: Why Your Two-Key Grouping Fails
As developers working with Laravel, we often deal with aggregating data. Whether we are working with Eloquent models or raw collections, grouping data is a fundamental operation. However, when you try to group a collection by multiple attributes, especially when dealing with complex relationships or database results, you often run into unexpected behavior.
I frequently see developers attempting to use the `groupBy()` method on Laravel Collections to achieve multi-dimensional grouping. My experience tells me that while collections are powerful, performing complex aggregations is often best handled where the data originates—in the database.
Let's dive into why your attempt might be failing and explore the correct, most efficient ways to group data in a Laravel application.
## The Pitfall of In-Memory Grouping
You mentioned trying to group an Eloquent result by two columns: `performed_at_year_month` and `performer_id`. Your initial code snippet looks like this:
```php
$query = Activity::all()->groupBy('performed_at_year_month', 'performer_id')->toJson();
```
The reason this often fails or only groups by the first key is due to how PHP's native `groupBy` method interacts with Eloquent’s collection methods. When you call `Activity::all()`, you retrieve all the data into a standard PHP Collection. While the `groupBy()` method *does* accept multiple keys, the fundamental issue often lies in performance and intent: are you grouping based on the properties of the records themselves, or are you aggregating results from a database?
If your goal is to group records fetched from the database, performing the grouping in PHP after fetching everything can be extremely inefficient, especially with large datasets. This approach forces Laravel to pull potentially millions of rows into memory just to sort them, which is exactly what we want to avoid when working with robust frameworks like those found at [https://laravelcompany.com](https://laravelcompany.com).
## Solution 1: Correct Grouping on an Existing Collection (In-Memory)
If you absolutely must perform the grouping in PHP *after* fetching the data, the syntax for multiple keys is correct within a standard collection context:
```php
$activities = Activity::all();
$groupedData = $activities->groupBy('performed_at_year_month', 'performer_id');
// Example output structure:
/*
[
'2023-10' => [
101 => [ /* ... records for performer 101 in Oct 2023 */ ],
102 => [ /* ... records for performer 102 in Oct 2023 */ ]
],
'2024-01' => [
101 => [ /* ... records for performer 101 in Jan 2024 */ ],
]
]
*/
```
While this works fine for small datasets, it is not scalable. For complex grouping based on database attributes, we should leverage the power of SQL.
## Solution 2: The Efficient Way – Grouping at the Database Level (Recommended)
The most performant and idiomatic way to group data is to let the database engine handle the aggregation using SQL's `GROUP BY` clause. This pushes the heavy lifting down to the database server, resulting in much faster query execution, especially when dealing with large tables.
You can achieve this using the Query Builder or Eloquent's advanced features:
### Using the Query Builder
If you are using the underlying Query Builder, the method is straightforward:
```php
use Illuminate\Support\Facades\DB;
$groupedResults = DB::table('activities')
->select(
'performed_at_year_month',
'performer_id',
DB::raw('count(*) as total_activities') // Add an aggregate function
)
->groupBy('performed_at_year_month', 'performer_id')
->get();
// $groupedResults will be a Collection of aggregated rows directly from the DB.
```
### Using Eloquent with Custom Aggregation
For more complex grouping where you need to calculate sums or averages within each group, using raw expressions alongside `groupBy` is necessary:
```php
$groupedActivityData = Activity::select(
'performed_at_year_month',
'performer_id',
DB::raw('SUM(amount) as total_spent') // Example aggregate
)
->groupBy('performed_at_year_month', 'performer_id')
->get();
```
By utilizing database-