The Truth About AddAsync: When to Use It in EF Core (and When Not To)

Let's crack open that EF Core mystery: Why does AddAsync() exist when there's no UpdateAsync() or RemoveAsync()? Feels like unfair treatment, right? Spoiler: It’s not favoritism—it’s about async value generation, not database calls. Let’s break it down.

The Big Misconception

AddAsync() does NOT talk to your database. Nope, not even a little. When you write:

await db.Users.AddAsync(user);

Zero bytes hit the database. All it does is tell EF: "Track this new entity; insert it later when I save." The actual INSERT happens at SaveChangesAsync().

So why Async? 🤔

The Real Reason: Async Value Generation

Imagine your entity needs a unique ID before saving, like a distributed Snowflake ID from an external service:

public class Order
{
    public long Id { get; set; } // Generated by a fancy async service!
    public string Customer { get; set; }
}

You’d write a custom generator:

public class SnowflakeIdGenerator : ValueGenerator<long>
{
    public override bool GeneratesTemporaryValues => false;

    public override ValueTask<long> NextAsync(EntityEntry entry, CancellationToken ct)
        => new ValueTask<long>(_GetIdAsync(ct));

    private async Task<long> _GetIdAsync(CancellationToken ct)
    {
        await Task.Delay(50, ct); // Simulate network call
        return DateTimeOffset.UtcNow.ToUnixTimeMilliseconds(); 
    }
}

The Problem: Blocking Threads

If you use synchronous Add():

var order = new Order { Customer = "ZèD" };
db.Orders.Add(order); // ← SYNC CALL (DANGER!)
await db.SaveChangesAsync();

EF tries to run NextAsync() synchronously. That Task.Delay(50)? It blocks your thread while waiting. In a busy ASP.NET Core app, this murders throughput.

How `AddAsync()` Saves the Day

var order = new Order { Customer = "ZèD" };
await db.Orders.AddAsync(order); // ← AWAITS async ID generation!
await db.SaveChangesAsync();

Now your async generator runs without blocking. No thread starvation, no performance bombs.

Why No `UpdateAsync`/`RemoveAsync`?

Simple: They don’t generate values.

Update(): Just marks entity as Modified. No async work needed.
Remove(): Just marks as Deleted. Nothing to await. Unless you’re doing something wild (like async blockchain lookups during deletion—please don’t), there’s no async step here.

When Should YOU Use `AddAsync`?

Scenario	Use `AddAsync`?	Why
Custom async value generators (IDs, audit stamps)	Yes	Avoids blocking threads
Async-first apps (e.g., ASP.NET Core)	Yes	Consistency & future-proofing
High-scale services	Yes	Prevents thread pool starvation
Simple apps with no async generators	Optional	`Add()` works fine too

Key Takeaways

AddAsync enables async value generation (like distributed IDs).
Updates/deletes don’t need async—they’re just state changes.
No hidden database calls in AddAsync—it’s all about pre-save logic.
Default to AddAsync in async code. It’s safer and more flexible.

So next time you see AddAsync, remember: it’s not EF playing favorites. It’s your secret weapon for non-blocking async workflows. And hey, if you really want RemoveAsync()… maybe go pet a dog instead.

TL;DR:

AddAsync() = Async value generation (e.g., IDs).

Update()/Remove() = No value generation → no Async needed.

Mofajjal Rasul @imzihad21