nHibernate 1.2, C# 2 and PostGres

I get good performances with this code:
for (int i = 0; i < 200; i++)
{
object myObj2 = session.Get(typeof(MyObject2), myObj2Id);
MyObject1 myObj1 = new MyObj1();
session.Save(myObj1);
}

but this code is very very slow:
for (int i = 0; i < 200; i++)
{
object myObj2 = session
.CreateQuery("from MyObject2 where id=?")
.SetInt32(0, myObj2Id)
.UniqueResult();
MyObject1 myObj1 = new MyObj1();
session.Save(myObj1);
}

Can someone explain me what is going on?

Please note that the standalone query or the standalone save are very fast. It is only when using both in the loop that it becomes very slow.

In the first case myObj2 is cached in the session, therefore, you are only hitting database once to retrieve the object with myObj2Id.

In the second case, you are hitting the database 200 times to retrieve myObj2. It is because you are issuing a query (using the criteria interface) and queries are not cached in the session, and they are only cache in the second-level cache if explicitly instructed to do so.

I explained the second-level cache mechanics here:
http://forum.hibernate.org/viewtopic.ph ... 65#2357765