Entity Framework Extensions Bulk Merge

Description

The EF BulkMerge extension method let you merge (insert or update/Upsert) a large number of entities in your database.

// Easy to use
context.BulkMerge(customers);

// Easy to customize
context.BulkMerge(customers, options => options.IncludeGraph = true);

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Performance Comparison

Operations 1,000 Entities 2,000 Entities 5,000 Entities
SaveChanges 4,000 ms To long... Way way to long...
BulkMerge 80 ms 110 ms 170 ms

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HINT:

A lot of factors might affect the benchmark time such as index, column type, latency, throttling, etc.

Scenarios

The BulkMerge method is fast but also flexible to let you handle various scenarios in Entity Framework such as:

What is supported?

  • All Entity Framework versions (EF4, EF5, EF6, EF Core, EF Classic)
  • All Inheritances (TPC, TPH, TPT)
  • Complex Type/Owned Entity Type
  • Enum
  • Value Converter (EF Core)
  • And more!

Advantages

  • Easy to use
  • Flexible
  • Increase performance
  • Increase application responsiveness
  • Reduce database load
  • Reduce database round-trips

Getting Started

Bulk Merge

The BulkMerge and BulkMergeAync methods extend your DbContext to let you merge a large number of entities in your database.

context.BulkMerge(customers);

context.BulkMergeAsync(customers, cancellationToken);

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Bulk Merge with options

The options parameter let you use a lambda expression to customize the way entities are inserted or updated.

context.BulkMerge(customers, options => options.ColumnPrimaryKeyExpression = c => c.Code });

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Why BulkMerge is faster than SaveChanges?

Merging thousands of entities for a file importation is a typical scenario.

The AddOrUpdate method performs a database round-trip for every entity to check if it already exists. The DetectChanges change method is also called for every entity which makes this method even slower (it's like using the Add method instead of AddRange).

The SaveChanges method performs one database round-trip for every entity to update.

So if you need to merge 10,000 entities, 20,000 database round-trips will be performed + 10,000 DetectChanges calls which is INSANELY slow.

The BulkMerge in counterpart requires the minimum database round-trips as possible. For example, under the hood for SQL Server, a SqlBulkCopy is performed first in a temporary table, then a MERGE from the temporary table to the destination table is performed which is the fastest way available.

Real Life Scenarios

Merge and keep identity value

Your entity has an identity property, but you want to force to insert a specific value instead. The MergeKeepIdentity option allows you to keep the identity value of your entity.

context.BulkMerge(customers, options => options.MergeKeepIdentity = true);

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Merge and include/exclude properties

You want to merge your entities but only for specific properties.

  • ColumnInputExpression: This option lets you choose which properties to map.
  • ColumnIgnoreExpression: This option lets you ignore properties that are auto-mapped.
  • IgnoreOnMergeInsertExpression: This option let you ignore properties only for the INSERT part.
  • IgnoreOnMergeUpdateExpression: This option let you ignore properties only for the UPDATE part.
context.BulkMerge(customers, options => options.ColumnInputExpression = c => new { c.CustomerID, c.Name} );
            
context.BulkMerge(customers, options => options.IgnoreOnMergeUpdateExpression = c => new { c.UpdatedDate } );

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Merge with custom key

You want to merge entities, but you don't have the primary key. The ColumnPrimaryKeyExpression let you use as a key any property or combination of properties.

context.BulkMerge(customers, options => options.ColumnPrimaryKeyExpression = c => c.Code);

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You want to merge entities but also automatically merge related child entities.

  • IncludeGraph: This option lets you to automatically merge all entities part of the graph.
  • IncludeGraphBuilder: This option lets you customize how to merge entities for a specific type.
context.BulkMerge(invoices, options => options.IncludeGraph = true);

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Merge with future action

You want to merge entities, but you want to defer the execution.

By default, BulkMerge is an immediate operation. That mean, it's executed as soon as you call the method.

FutureAction: This option lets you defer the execution of a Bulk Merge. ExecuteFutureAction: This option trigger and execute all pending FutureAction.

context.FutureAction(x => x.BulkMerge(customers));
context.FutureAction(x => x.BulkMerge(invoices, options => options.IncludeGraph = true));

// ...code...

context.ExecuteFutureAction();

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More scenarios

Hundreds of scenarios have been solved and are now supported.

The best way to ask for a special request or to find out if a solution for your scenario already exists is by contacting us: info@zzzprojects.com

Documentation

BulkMerge

Methods
Name Description Example
BulkMerge<T>(items) Bulk merge entities in your database. Try it
BulkMerge<T>(items, options) Bulk merge entities in your database. Try it
BulkMergeAsync<T>(items) Bulk merge entities asynchronously in your database.
BulkMergeAsync<T>(items, cancellationToken) Bulk merge entities asynchronously in your database.
BulkMergeAsync<T>(items, options, cancellationToken) Bulk merge entities asynchronously in your database.
Options

More options can be found here: