Querying, tracking vs no-tracking — Entity Framework (EF6 & EF Core)

7. Querying, tracking vs no-tracking

Basic★ Must knowLesson 7 of 15

csharp

var c = await db.Customers.FindAsync(5);                         // checks the change tracker first, then DB
var active = await db.Customers.Where(x => x.IsActive).OrderBy(x => x.Name).ToListAsync(ct);

// Read-only: skip change tracking (faster, less memory)
var list = await db.Products.AsNoTracking().Where(p => p.Price > 100).ToListAsync(ct);

// Projection — best for read models; selects only needed columns, never tracked
var dtos = await db.Orders
    .Where(o => o.CreatedAt >= from)
    .Select(o => new OrderDto(o.Id, o.Customer.Name, o.Total))
    .ToListAsync(ct);

AsNoTrackingWithIdentityResolution() — no tracking but still one instance per key. Configure default: UseQueryTrackingBehavior(QueryTrackingBehavior.NoTracking) for read-heavy contexts.