def get_last_tid(self):
        try:
            spec = {'tid': {'$gt': 0}}
            sort = [('tid', -1)]
            row = self.db.docs.find_one(spec, sort=sort)
        except Exception as e:
            raise DatabaseException(e)
        if row:
            return row['tid']
        return 0
def _swdb_group_upgrade(self, group_id, pkg_types, pkgs):
        if not self._base.history.group.get(group_id):
            self._raise_or_warn( self._ignore_installed, _("Group id '%s' is not installed.") % group_id)
            return

        swdb_group = self._create_swdb_group(group_id, pkg_types, pkgs)

        if swdb_group is not None:
            self._base.history.group.upgrade(swdb_group)