Why should you care?

When a ShopNest admin edits only Product.Price, EF must UPDATE Price — not rewrite every column blindly.

See it live — copy this example

Paste into a .NET project with EF Core packages, then run with LocalDB/SQL Server (dotnet ef / dotnet run).

var product = await _context.Products.FindAsync(5);
product!.Price = 1499; // tracker marks Price Modified

var entry = _context.Entry(product);
Console.WriteLine(entry.State); // Modified

await _context.SaveChangesAsync();
// UPDATE Products SET Price = @p0 WHERE Id = 5

What happened?

• FindAsync loads and tracks the entity.
• Mutating Price updates the tracker.
• Entry exposes EntityState before save for debugging.

Practice next

1. Load one product, change one property, inspect entry.State.
2. Compare tracked update vs loading with AsNoTracking then Attach.
3. List states: Added, Modified, Deleted, Unchanged, Detached on paper.
4. Call entry.Property(p => p.Price).IsModified to see granular flags.
5. Use _context.ChangeTracker.Clear() mid-request and observe Detached behavior.

Remember

Change tracker records edits per property. EntityState shows what SaveChanges will do. Tracking has memory cost on large result sets.

ShopNest price update audit

Pricing service loads a tracked Product, changes Price, and SaveChangesAsync writes a single-column UPDATE.

Outcome: Minimal write lock time on hot catalog rows during flash sales.