Are elements returned by Linq-to-Entities query streamed from the database one at the time ( as they are requested ) or are they retrieved all at once:

    SampleContext context = new SampleContext(); // SampleContext derives from ObjectContext
    var search = context.Contacts;

    foreach (var contact in search)
    {
       Console.WriteLine(contact.ContactID); // is each Contact retrieved from the DB 
                                             // only when foreach requests it?
    }

thank you in advance