Entity Framework Change Tracking
I needed to know how the Entity Framework does its change tracking, so I wrote a simple test to see what’s happening. Since we only needed to know what happened when you modify a property on an entity, I focused on that aspect (and not how deleting entities is tracked, for example).
Anyway: my conclusions… It seems that the Entity Framework sets the EntityState of an entity to Modified anytime you change a property. It does not matter what value you put in it.
To put this in a small list. The Modified state appears…
- … when you assign a different value (obviously)
- … when you assign a different value and then assign the previous value
- … when you assign the same value
So once an Entity is touched, there’s no way of telling if a property contains the original value or not.
Good to know. 
i just stumbled across this in rc1, I can’t believe that it hasn’t gotten more attention.