Table Splitting in EF Core

What is Table Splitting?

Table splitting maps multiple entity types to a single database table. It’s useful for separating frequently and infrequently accessed data.

Basic Configuration

public class Order
{
    public int Id { get; set; }
    public DateTime OrderDate { get; set; }
    public decimal TotalAmount { get; set; }
    public OrderDetails Details { get; set; }
}

public class OrderDetails
{
    public int Id { get; set; }
    public string Notes { get; set; }
    public string InternalComments { get; set; }
    public Order Order { get; set; }
}

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.Entity<Order>()
        .ToTable("Orders");
    
    modelBuilder.Entity<OrderDetails>()
        .ToTable("Orders");
    
    modelBuilder.Entity<Order>()
        .HasOne(o => o.Details)
        .WithOne(d => d.Order)
        .HasForeignKey<OrderDetails>(d => d.Id);
}

Usage

// Load only main entity
var order = await context.Orders.FindAsync(id);

// Load with details
var orderWithDetails = await context.Orders
    .Include(o => o.Details)
    .FirstAsync(o => o.Id == id);

Summary

Table splitting in EF Core maps multiple entities to one table. Configure using ToTable() with same table name and one-to-one relationship. Useful for performance optimization.