EFCore.BulkExtensions

EntityFrameworkCore extensions for Bulk operations (Insert, Update, Delete).
Library is Lightweight and very Efficient, having all mostly used CUD operation.
It is targeting NetStandard 2.0 so it can be used on project targeting NetCore(2.0+) or NetFramework(4.6.1+).
Current version is using EF Core 2.1.
For EF Core 2.0 install 2.0.8 Nuget, and for EF Core 1.x use 1.1.0 (targeting NetStandard 1.4)
Under the hood uses SqlBulkCopy for Insert, for Update/Delete combines BulkInsert with raw Sql MERGE (MsSQL 2008+).

Available on NuGet. Latest 2.1.2
Package manager console command for installation: Install-Package EFCore.BulkExtensions

Usage is simple and pretty straightforward.
Extensions are made on DbContext class and can be used like this (both regular and Async methods are supported):

context.BulkInsert(entitiesList);                context.BulkInsertAsync(entitiesList);
context.BulkUpdate(entitiesList);                context.BulkUpdateAsync(entitiesList);
context.BulkDelete(entitiesList);                context.BulkDeleteAsync(entitiesList);
context.BulkInsertOrUpdate(entitiesList);        context.BulkInsertOrUpdateAsync(entitiesList);

In ConnectionString there should be Trusted_Connection=True; because Sql credentials are required to stay in connection.

When used directly each of these operations are separate transactions and are automatically committed.
And if we need multiple operations in single procedure then explicit transaction should be used, for example:

using (var transaction = context.Database.BeginTransaction())
{
    context.BulkInsert(entitiesList);
    context.BulkInsert(subEntitiesList);
    transaction.Commit();
}

BulkInsertOrUpdate method can be used when there is need for both operations but in one connection to database.
It makes Update when PK is matched, otherwise does Insert.

BulkConfig arguments

BulkInsert and BulkInsertOrUpdate methods can have optional argument BulkConfig with properties (bool, int, object, List):
{ PreserveInsertOrder, SetOutputIdentity, BatchSize, NotifyAfter, BulkCopyTimeout, EnableStreaming, UseTempDB, WithHoldlock, PropertiesToInclude, PropertiesToExclude, UpdateByProperties, SqlBulkCopyOptions }
Default behaviour is { false, false, 2000, null, null, false, false, true, null, null, null, Default } and if we want to change it, BulkConfig should be added explicitly with one or more bool properties set to true, and/or int props like BatchSize to different number.
When doing update we can chose to exclude one or more properties by adding their names into PropertiesToExclude, or if we need to update less then half column then PropertiesToInclude can be used. Setting both Lists are not allowed. Additionaly there is UpdateByProperties that allows specifying custom properties, besides PK, by which we want update to be done.
If NotifyAfter is not set it will have same value as BatchSize while BulkCopyTimeout when not set has SqlBulkCopy default which is 30 seconds and if set to 0 it indicates no limit.
PreserveInsertOrder and SetOutputIdentity have purpose only when PK has Identity (usually int type with AutoIncrement), while if PK is Guid(sequential) created in Application there is no need for them. Also Tables with Composite Keys have no Identity column so no functionality for them in that case either.

context.BulkInsert(entitiesList, new BulkConfig { PreserveInsertOrder = true, SetOutputIdentity = true, BatchSize = 4000});
context.BulkInsertOrUpdate(entitiesList, new BulkConfig { PreserveInsertOrder = true });

PreserveInsertOrder makes sure that entites are inserted to Db as they are ordered in entitiesList.
However for this to work Id column needs to be set for the proper order.
For example if table already has rows, let's say it has 1000 rows with Id-s (1:1000), and we now want to add 300 more.
Since Id-s are generated in Db we could not set them, they would all be 0 (int default) in list.
But if we want to keep the order as they are ordered in list then those Id-s should be set say 1 to 300.
Here single Id value itself doesn't matter, db will change it to (1001:1300), what matters is their mutual relationship for sorting.
Insertion order is implemented with TOP in conjuction with ORDER BY. stackoverflow:merge-into-insertion-order.

When using PreserveInsertOrder with BulkInsertOrUpdate method, Id value does matter for those that will be updated.
If we need to sort those for insert and not have conflict with existing Id-s, there are 2 ways:
One is set Id to really high values, order of magnitude 10^10, and another even better setting them to negative values.
So if we have list of 8000, say 3000 for update (they keep the real Id) and 5000 for insert then Id-s could be (-5000:-1).

SetOutputIdentity is useful when BulkInsert is done to multiple related tables, that have Identity column.
So after Insert is done to first table, we need Id-s that were generated in Db becasue they are FK in second table.
It is implemented with OUTPUT as part of MERGE Query, so in this case even the Insert is not done directly to TargetTable but to TempTable and then Merged with TargetTable.
When used if PreserveInsertOrder is also set to true Id-s will be updated in entitiesList, and if PreserveInsertOrder is false then entitiesList will be cleared and reloaded.

UseTempDB can be used only with Insert operation.

SqlBulkCopyOptions is Enum with [Flags] attribute which enables specifying one or more options:
Default, KeepIdentity, CheckConstraints, TableLock, KeepNulls, FireTriggers, UseInternalTransaction

Last optional argument is Action progress (Example in EfOperationTest.cs RunInsert() with WriteProgress()).

context.BulkInsert(entitiesList, null, (a) => WriteProgress(a));

Library supports Global Query Filters and Value Conversions as well.
It also maps OwnedTypes, but when that is used it will work only if Properties of Entity are in the same order as DbColumns, because this is implemented with DataTable class.
With Computed and Timestamp Columns it will work in a way that they are automatically excluded from Insert. And when combined with SetOutputIdentity then ComputedColumns will be Selected while Timestamp will not (it will stay Null).

TPH inheritance

When having TPH (Table-Per-Hierarchy) inheritance model it can be set in 2 ways.
First is automatically by Convention in which case Discriminator column is not directly in Entity but is Shadow Property.
And second is to explicitly define Discriminator property in Entity and configure it with .HasDiscriminator().
Important remark regarding the first case is that since we can not set directly Discriminator to certain value we need first to add list of entities to DbSet where it will be set and after that we can call Bulk operation. Note that SaveChanges are not called and we could optionally turn of TrackingChanges for performance. Example:

public class Student : Person { ... }
context.Students.AddRange(entities); // adding to Context so that Shadow property 'Discriminator' gets set
context.BulkInsert(entities);

Performances

Following are performances (in seconds):

Operations\Rows	100,000 EF	100,000 EFBulk	1,000,000 EFBulk
Insert	38.98 s	2.10 s	17.99 s
Update	109.25 s	3.96 s	31.45 s
Delete	7.26 s	2.04 s	12.18 s
-----------------	------------	----------------	------------------
Together	70.70 s	5.88 s	56.84 s

TestTable has 6 columns (Guid, string, string, int, decimal?, DateTime).
All were inserted and 2 of them (string, DateTime) were updated.
Test was done locally on following configuration: INTEL Core i5-3570K 3.40GHz, DDRIII 8GB x 2, SSD 840 EVO 128 GB.

Contributing

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Please read CONTRIBUTING.md for details on code of conduct, and the process for submitting pull requests.

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