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Exercise 1: EF Core Optimization

Objective​

Fix N+1 problems and optimize queries

Task​

Given a slow endpoint, optimize it:

// Slow version
var orders = await context.Orders.ToListAsync();
foreach (var order in orders)
{
    order.Customer = await context.Customers.FindAsync(order.CustomerId);
    order.Items = await context.OrderItems.Where(i => i.OrderId == order.Id).ToListAsync();
}

Solutions to Implement​

  1. Eager loading with Include
  2. Projection with Select
  3. Split queries for multiple collections
  4. AsNoTracking for read-only
  5. Compiled queries

Expected Outcome​

  • 10x+ performance improvement
  • Understanding of query execution