What is Entity Framework Identity Resolution?

Identity Resolution is EF Core’s mechanism for tracking entity instances by primary key. When you query for an entity that’s already been loaded into the DbContext, EF returns the existing in-memory instance instead of creating a new one from the database. This improves performance but can lead to stale data if not managed properly.

Why would two database queries for the same row return different values?

If one query hits the Identity Resolution cache (returning a tracked, potentially stale instance) and another uses AsNoTracking() to bypass the cache, they can return different values. The tracked instance reflects whatever state EF last loaded, while the untracked query fetches the current database value.

What happens when you create multiple DbContext instances in the same request?

Each DbContext maintains its own change tracker and Identity Resolution cache. Changes saved through one context, like incrementing a counter, are completely invisible to another context. This can cause one context to silently overwrite changes made by the other when it saves.

How do you bypass Identity Resolution in Entity Framework?

Use .AsNoTracking() on your LINQ query to skip EF’s change tracker and fetch data directly from the database. You can also use raw SQL via FromSqlRaw() or Database.ExecuteSqlRaw(). These approaches are useful for debugging and for read-only queries where tracking isn’t needed.

What is the best practice for managing DbContext in .NET applications?

Use Dependency Injection to manage the DbContext lifetime. Register it with AddDbContext<T>() in your service collection and inject it via constructors. This ensures all components in a single HTTP request share the same DbContext, preventing identity cache conflicts. Never instantiate new DbContext() manually in helper classes or services.