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Create an Index for you Entity Framework Index

Posted on: March 27, 2015

Either you are working with a field that require a fast access or if the field is used as reference in some case, you will need to create an Index. Unfortunately, Entity Framework does not offer a quick way to do it. To tell Entity Framework to generate the Sql Index on the column, you must use a Column Annotation. Entity Framework column annotation has an already created class named IndexAnnotation that can be added to your column.

this.Property(d => d.Date) .HasColumnAnnotation("Index" , new IndexAnnotation( new IndexAttribute("IX_Date") {IsUnique = true} ) );
``` The code above set for a _Date_ column an **index**. It creates a IndexAnnotation which create a unique index attribute.
This result into an Index inside the migration class with a unique property set to true.
```csharp
CreateTable( "YourEntityName", c => new { Id = c.Int(nullable: false, identity: true), Date = c.DateTime(nullable: false), }) .PrimaryKey(t => t.Id) .Index(t => t.Date, unique: true);