The New LINQ Methods from .NET 6 to .NET 9: A Friendly Guide

LINQ is one of the most loved parts of C#. It lets you ask questions about a list of data in a short, readable way. Things like "give me the oldest student" or "group these orders by city" become one neat line of code.

From .NET 6 to .NET 9, Microsoft added many small but powerful LINQ methods. Each one removes some boring boilerplate you used to write by hand. In this guide we will meet them one by one, with simple words and tiny examples that a beginner can follow.

A real-life way to think about LINQ

Imagine your grandmother has a big steel box full of mixed lentils and rice. She wants to do many things with it. Sometimes she wants only the biggest grains. Sometimes she wants to split everything into small bowls for each family member. Sometimes she wants to count how many grains of each colour are there.

Before, she had to do all of this by hand, grain by grain. Slow and tiring.

Now imagine someone gives her a smart kitchen helper. She just says "split this into 4 bowls" or "find me the biggest grain" and it happens instantly. She does not change her kitchen. She just gets better tools.

The new LINQ methods are exactly like that smart helper. The data is the same. Your loops would still work. But these methods say what you want in one short line, and the computer does the boring part for you.

How LINQ methods run (deferred execution)

Before we jump in, one important idea. Most LINQ methods are lazy. They do not do the work right away. They wait until you actually ask for the result, like in a foreach loop or when you call ToList().

This is called deferred execution. It is helpful because the computer can skip work it does not need.

Keep this in mind. Some of the new methods, like Chunk, only give you pieces when you start looping.

.NET 6: the big batch of new helpers

.NET 6 was a huge release for LINQ. It added many methods that people had been writing by hand for years. Let us look at the most useful ones.

MinBy and MaxBy

Before, to find the student with the highest marks, you had to sort the whole list and take the first one. That is wasteful. MaxBy and MinBy find it directly using a key.

using System.Linq;
 
record Student(string Name, int Marks);
 
var students = new List<Student>
{
    new("Aarav", 82),
    new("Diya", 91),
    new("Kabir", 77)
};
 
// The single student with the highest marks
Student topper = students.MaxBy(s => s.Marks);   // Diya, 91
 
// The single student with the lowest marks
Student lowest = students.MinBy(s => s.Marks);   // Kabir, 77

Notice you get back one whole Student object, not just the number. That is the magic. You said "the one with the biggest marks" and you got the full person back.

DistinctBy, ExceptBy, UnionBy, IntersectBy

The old Distinct removed duplicates by comparing whole objects. But often you want "unique by one field", like one row per city. The new ...By methods let you give a key.

var orders = new List<Order>
{
    new("Mumbai", 100),
    new("Delhi", 250),
    new("Mumbai", 90)   // same city as the first
};
 
// Keep only one order per city
var oneEach = orders.DistinctBy(o => o.City).ToList();
// Result: Mumbai 100, Delhi 250

ExceptBy, UnionBy and IntersectBy work the same way. They compare by a key you choose instead of the whole object. This saves you from writing custom comparer classes.

Chunk

Chunk splits one long list into smaller lists of a fixed size. This is perfect when you send data to an API in small batches, or show items page by page.

int[] numbers = { 1, 2, 3, 4, 5, 6, 7 };
 
foreach (int[] batch in numbers.Chunk(3))
{
    Console.WriteLine(string.Join(", ", batch));
}
// Output:
// 1, 2, 3
// 4, 5, 6
// 7

The last chunk can be smaller, as you see above. That is normal and safe.

Take with a range

.NET 6 also let you slice a list using C# range syntax. Instead of mixing Skip and Take, you write one clean expression.

int[] items = { 10, 20, 30, 40, 50 };
 
var middle = items.Take(1..4);   // 20, 30, 40
var lastTwo = items.Take(^2..);  // 40, 50

The ^2 means "two from the end". It reads almost like plain English.

Here is a quick table of the main .NET 6 additions so you can see them together.

.NET 7: cleaner ordering

.NET 7 was smaller for LINQ, but it added two very tidy methods: Order and OrderDescending.

Before, to sort a simple list of numbers you had to write numbers.OrderBy(x => x). That x => x part is pure noise. The new method removes it.

int[] scores = { 50, 10, 30 };
 
var up = scores.Order();            // 10, 30, 50
var down = scores.OrderDescending(); // 50, 30, 10

For lists of simple types like numbers, dates, or strings, this reads much better. You only need OrderBy when you sort by a key, like a property of an object.

.NET 8: small comfort improvements

.NET 8 focused more on performance and on small quality-of-life touches across the library. For everyday LINQ, the headline is that the range-based Take and the ...By family from earlier releases became even more polished and were widely adopted in real projects.

A pattern many teams started using in .NET 8 is combining the newer methods to replace long manual loops. For example, taking the top three products per category becomes short and clear.

var topThreePerCategory = products
    .GroupBy(p => p.Category)
    .SelectMany(group => group
        .OrderDescending()          // .NET 7 method
        .Take(..3));                // .NET 6 range slice
 
// One readable pipeline instead of nested loops

The lesson here is that these methods are like LEGO bricks. Each release adds a few bricks, and together they let you build clear pipelines without writing low-level loop code.

.NET 9: grouping and counting get superpowers

.NET 9 added three methods that many developers had wished for. They turn common multi-step jobs into a single call.

CountBy

Counting how many items fall into each group used to need GroupBy followed by a Select that calls Count(). CountBy does it in one step and is faster, because it does not build the full groups in memory.

string[] votes = { "yes", "no", "yes", "yes", "no" };
 
foreach (var pair in votes.CountBy(v => v))
{
    Console.WriteLine($"{pair.Key}: {pair.Value}");
}
// yes: 3
// no: 2

You get back key and count pairs directly. Clean and quick.

AggregateBy

AggregateBy is like CountBy, but instead of just counting, you can run any custom math per group. Think of summing the total bill per customer.

var sales = new List<Sale>
{
    new("Riya", 100),
    new("Riya", 50),
    new("Sam", 70)
};
 
var totalPerPerson = sales.AggregateBy(
    keySelector: s => s.Name,
    seed: 0,
    func: (total, sale) => total + sale.Amount);
 
// Riya -> 150, Sam -> 70

Here seed is the starting value for each group, and func says how to add each item in. This replaces a fair bit of dictionary code.

Index

The Index method gives you each item together with its position number, without writing a counter variable yourself.

string[] fruits = { "mango", "apple", "guava" };
 
foreach (var (i, fruit) in fruits.Index())
{
    Console.WriteLine($"{i}: {fruit}");
}
// 0: mango
// 1: apple
// 2: guava

Before, people used Select((value, index) => ...), which was wordy. Index() is shorter and easier to read.

Putting it on a timeline

It helps to see which method arrived with which release. Here is a simple table.

A friendly word of caution with databases

If you use Entity Framework Core, remember that your LINQ query may be turned into SQL and run on the database. Not every new method can be translated to SQL.

Methods like Order, OrderDescending, and range Take usually translate fine. But newer in-memory helpers like CountBy or Index may run after the rows are loaded into memory. For a small list that is fine. For a giant table, it could be slow.

The safe habit is to log or inspect the SQL your query produces, especially in .NET 9. When in doubt, test with real data.

Why these methods matter for a beginner

You might think, "I can write a loop for all of this." That is true. But shorter code has fewer places for bugs to hide. When a reader sees students.MaxBy(s => s.Marks), they instantly know what you mean. A hand-written loop takes longer to read and is easier to get wrong.

These methods also tend to be faster, because the .NET team wrote them carefully. CountBy, for example, avoids building full groups in memory. So you get cleaner code and better speed at the same time. That is a rare and lovely combination.

Quick recap

• LINQ lets you ask questions about a list in one short, readable line.
• .NET 6 added MinBy, MaxBy, DistinctBy, Chunk, and range-based Take.
• .NET 7 added Order and OrderDescending so you can drop the noisy x => x.
• .NET 8 polished these methods and made clean pipelines popular.
• .NET 9 added CountBy, AggregateBy, and Index for one-step grouping, counting, and indexing.
• All of them live in System.Linq and need no extra NuGet package.
• With Entity Framework Core, check the generated SQL, because not every method translates.

References and further reading

• LINQ overview (Microsoft Learn)
• System.Linq.Enumerable API (Microsoft Learn)
• Enumerable.OrderDescending (Microsoft Learn)
• The New LINQ Methods from .NET 6 to .NET 9 (antondevtips)
• Four new LINQ methods in .NET 6 (Just Some Code)