N+1 queries in EF Core

Detailed answer

N+1 happens when you load a list then lazily access navigation properties per item. Fix with Include/ThenInclude, AsSplitQuery for large graphs, projection to DTOs with Select, or explicit Join. Detect with logging, MiniProfiler, or Application Insights SQL dependency traces.

Code example

var orders = await db.Orders
    .AsNoTracking()
    .Include(o => o.Items)
    .Where(o => o.CustomerId == id)
    .Select(o => new OrderDto(o.Id, o.Items.Count))
    .ToListAsync(ct);