Entity Framework Extensions AllowDuplicateKeys


The BulkOperation.AuditEntries property gets or sets if a duplicate key is possible in the source.

The following example chooses a Name property as a key to perform the BulkMerge operations and also allows a duplicate key.

var list = new List<Customer>() 
    new Customer() { Name = "Customer_A", Description = "Description_updated" },
    new Customer() { Name ="Customer_B", Description = "Description"}    
using (var context = new EntityContext())
    context.BulkMerge(list,options => 
        options.ColumnPrimaryKeyExpression = customer => customer.Name;
        options.AllowDuplicateKeys = true;

Try it: EF Core | EF6

  • It will update the record of "Customer_A" because it already exists in the database.
  • The data for "Customer_B" is inserted to the database as a new record.


In a rare scenario such as importing a file, a key may be used in multiple rows.

In some provider such as SQL Server, the statement created by our library (Merge) makes it impossible to use with some duplicate keys.

By enabling this option, only the latest key is used instead.

Last updated: 2023-03-01