Question

Lets say I have two entities: Stable, and Pony.

Stable has an IList<Pony> with a HasMany mapping configured with Cascade.All().

That means that if I do session.Save(myStable), each Pony in the collection will be saved.

However, what happens if I do this?

Pony myLittlePony = new Pony(Color.Brown);
Stable myStable = new Stable(WoodTypes.RichMahogany);
myStable.Ponies.Add(myLittlePony);

session.Save(myStable);
session.Save(myLittlePony);

Will NHibernate try to save myLittlePony twice? or is NHibernate “smart” enough to know that myLittlePony has already been persisted to the DB?

Are there any performance implications from doing something like this?

Answer 1

NHibernate is pretty smart, and AFAIK, since myLittlePony would still be in the session and have no changes (IsDirty returning false), it won’t trigger another flush to the persistence medium.