gistfile1.cs

    public class Program
    {
        private static void Main(string[] args)
        {
            File.Delete("tmp.db4o");

            using (var db = OpenDB())
            {
                var usr = new User();
                db.Store(usr);
            }
            using (var db = OpenDB())
            {
                var usr = GetUser(db);
                // we add another item
                usr.Tattoos.Add(new Tattoo());
            }
            using (var db = OpenDB())
            {
                var usr = GetUser(db);

                // returns 1 as expected
                Console.Out.WriteLine("Count of tattoos is {0}", usr.Tattoos.Count);
            }
            Console.Out.WriteLine("DONE, hit enter to exit");
            Console.Read();
        }

        private static User GetUser(IObjectContainer db)
        {
            return (from User user in db
                    select user).First();
        }

        private static IEmbeddedObjectContainer OpenDB()
        {
            return Db4oEmbedded.OpenFile(NewConfig(), "tmp.db4o");
        }

        private static IEmbeddedConfiguration NewConfig()
        {
            var cfg = Db4oEmbedded.NewConfiguration();
            cfg.Common.Add(new TransparentPersistenceSupport());
            return cfg;
        }
    }