Chat one to one схема

[Stalkert]

Есть задача организовать диалоги между пользователями. Сообщения должны хранятся на сервере неделю. Какая лучше схема организации таблиц в БД?

гуглом нашел типа этого:

class Dialog(TimeStampedModel):
    owner = models.ForeignKey(settings.AUTH_USER_MODEL, verbose_name=_("Dialog owner", related_name="selfDialogs",
                              on_delete=models.CASCADE)
    opponent = models.ForeignKey(settings.AUTH_USER_MODEL, verbose_name=_("Dialog opponent", on_delete=models.CASCADE)

    def __str__(self):
        return _("Chat with " + self.opponent.username


class Message(TimeStampedModel, SoftDeletableModel):
    dialog = models.ForeignKey(Dialog, verbose_name=_("Dialog", related_name="messages", on_delete=models.CASCADE)
    sender = models.ForeignKey(settings.AUTH_USER_MODEL, verbose_name=_("Author", related_name="messages",
                               on_delete=models.CASCADE)
    text = models.TextField(verbose_name=_("Message text")
    read = models.BooleanField(verbose_name=_("Read", default=False)
    all_objects = models.Manager()

    def get_formatted_create_datetime(self):
        return dj_date(localtime(self.created), settings.DATETIME_FORMAT)

    def __str__(self):
        return self.sender.username + "(" + self.get_formatted_create_datetime() + " - '" + self.text + "'"

 chat, database modelling