/// <exception cref="Db4objects.Db4o.Internal.FieldIndexException"></exception>
        public override void AddFieldIndex(ObjectIdContextImpl context)
        {
            LocalTransaction     transaction    = (LocalTransaction)context.Transaction();
            LocalObjectContainer localContainer = (LocalObjectContainer)transaction.Container
                                                      ();
            Slot oldSlot                = transaction.IdSystem().CommittedSlot(context.ObjectId());
            int  savedOffset            = context.Offset();
            int  db4oDatabaseIdentityID = context.ReadInt();
            long uuid = context.ReadLong();

            context.Seek(savedOffset);
            bool isnew = (oldSlot.IsNull());

            if ((uuid == 0 || db4oDatabaseIdentityID == 0) && context.ObjectId() > 0 && !isnew)
            {
                UUIDFieldMetadata.DatabaseIdentityIDAndUUID identityAndUUID = ReadDatabaseIdentityIDAndUUID
                                                                                  (localContainer, context.ClassMetadata(), oldSlot, false);
                db4oDatabaseIdentityID = identityAndUUID.databaseIdentityID;
                uuid = identityAndUUID.uuid;
            }
            if (db4oDatabaseIdentityID == 0)
            {
                db4oDatabaseIdentityID = localContainer.Identity().GetID(transaction);
            }
            if (uuid == 0)
            {
                uuid = localContainer.GenerateTimeStampId();
            }
            StatefulBuffer writer = (StatefulBuffer)context.Buffer();

            writer.WriteInt(db4oDatabaseIdentityID);
            writer.WriteLong(uuid);
            if (isnew)
            {
                AddIndexEntry(writer, uuid);
            }
        }