🧩 EF Core Bulk Merge / Upsert with Entity Framework Extensions

The BulkMerge method from Entity Framework Extensions is an UPSERT operation made for EF Core that combines both insert and update into a single, efficient database call.

• If the data exists, it will be updated
• If the data doesn’t exist, it will be inserted

This operation is also commonly called upsert, add or update, or insert or update.

EF Core doesn't offer a similar operation, so using the bulk merge method from Entity Framework Extensions is the only recommended solution.

In this example, we will merge two customers:

• The "ZZZ Projects" customer will be inserted since it doesn't exist
• The "Jonathan Magnan" customer will be inserted or updated depending on whether ID = 13 is found in the database

// @nuget: Z.EntityFramework.Extensions.EFCore
using Z.EntityFramework.Extensions;
var customers = new List<Customer>
{
    new Customer { Name = "ZZZ Projects", City = "New York" },
    new Customer { ID = 13, Name = "Jonathan Magnan", City = "Montreal" }
    // Add more customers as needed
};
using (var context = new YourDbContext())
{
    // Easy to use
    context.BulkMerge(customers);
    
    // Easy to customize
    context.BulkMerge(customers, options => options.IncludeGraph = true);
}
using (var context = new YourDbContext())
{
    // Supports async
    await context.BulkMergeAsync(customers);
}

🚀 Why Use the Bulk Merge Method from Entity Framework Extensions?

The BulkMerge method from Entity Framework Extensions is the recommended solution for EF Core when you need to add or update a large number of entities very fast.

Entity Framework Extensions is the most popular and most complete library available, with over 50 million downloads and more than 5,000 paid customers. Bulk merging in EF Core with Entity Framework Extensions is up to 5x faster, reducing execution time by up to 80% (Online Benchmark).

Here’s why developers choose it:

• ✅ Add or update the way you want – Define custom keys, control which properties to insert or update, and apply conditions that fit your logic.
• ✅ Extremely fast – Handle thousands — even millions — of upserts in seconds. See the Performance Comparison.
• ✅ No need to load entities – Save memory and time by working directly with your data — no tracking or pre-loading required.
• ✅ Flexible with hundreds of options – Customize the behavior to match your business rules, from conditional updates to advanced key matching. Explore Bulk Merge Options

🛠️ Commonly Used Options with the Bulk Merge Method from Entity Framework Extensions

Here are some of the most frequently used options with the BulkMerge method from the Entity Framework Extensions library:

• OnMergeInsertInputExpression – Use a lambda expression to choose which properties should be inserted during the insert phase of the merge operation. This option does not affect properties that will be updated.
• OnMergeUpdateInputExpression – Use a lambda expression to choose which properties should be updated during the update phase of the merge operation. This option does not affect properties that will be inserted.
• IgnoreOnMergeInsertExpression – Use a lambda expression to choose which properties should be ignored during the insert phase. All other properties will be inserted. This option does not affect the update phase.
• IgnoreOnMergeUpdateExpression – Use a lambda expression to choose which properties should be ignored during the update phase. All other properties will be updated. This option does not affect the insert phase.
• IgnoreOnMergeInsert – Set to true if you want to skip the insert phase of the merge operation.
• IgnoreOnMergeUpdate – Set to true if you want to skip the update phase of the merge operation.
• IncludeGraph – Set to true if you want to merge both the main entities and their related entities. For example, if you pass a list of Order that includes OrderItem, both will be merged. ⚠️ Note: If you want to apply specific options to a related entity type, you’ll need to configure them using IncludeGraphBuilder.
• ColumnPrimaryKeyExpression – Use a lambda expression to define which properties should be used as the primary key. Only rows that match this key will be updated — all others will be inserted.
• RowsAffected – Set UseRowsAffected = true to access merge result information. After the operation, you can check:
  • ResultInfo.RowsAffected
  • ResultInfo.RowsAffectedInserted
  • ResultInfo.RowsAffectedUpdated Learn more

📦 How to Install Entity Framework Extensions

To use the bulk merge method, install the Z.EntityFramework.Extensions.EFCore NuGet package:

PM> NuGet\Install-Package Z.EntityFramework.Extensions.EFCore

> dotnet add package Z.EntityFramework.Extensions.EFCore

Entity Framework Extensions uses EF Core pinned versioning, so make sure the first digit of the package version matches your EF Core version. For example:

• If you're using EF Core 9, use version v9.x.y.z
• If you're using EF Core 8, use version v8.x.y.z
• And so on...

Looking for a different version, like BulkMerge for EF6? 👉 Download it here

✅ Final Thoughts

If you're still inserting or updating data using regular EF Core logic, it might be time to level up.

With just one line of code, the bulk merge method from Entity Framework Extensions lets you:

• Skip unnecessary reads
• Merge thousands of entities in seconds
• Fully control how inserts and updates behave

Whether you’re syncing records, importing external data, or cleaning up your database — the bulk merge method gives you the speed, flexibility, and simplicity you've been missing.

Give it a try and see why over 5,000 companies trust Entity Framework Extensions for their bulk operations. Once you use it, you'll wonder how you ever worked without it.

🔗 External Links

Looking for more resources? Here are some helpful links to learn more about the BulkMerge method and Entity Framework Extensions, explore its documentation, and download the right version for your project.

📘 Documentation

• 🔗 Bulk Merge – Official Documentation
• 🔗 Entity Framework Extensions – Overview

📦 Downloads & Packages

• 🔗 NuGet Package – Z.EntityFramework.Extensions.EFCore
• 🔗 Download Page – All Versions (EF6, EF Core, etc.)