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 execute(self, sql, params=None):
        result = self._no_monkey.execute(self, sql, params)
        if transaction_states[self.db.alias] and is_sql_dirty(sql):
            transaction_states[self.db.alias].mark_dirty()
        return result