models.py 文件源码

def calculate_filter_max_counters(cls, filters):

        # create string of prefixes to place into sql statement
        condition = " UNION ".join(["SELECT '{}' AS a".format(prefix) for prefix in filters])

        filter_max_calculation = """
        SELECT PMC.instance, MIN(PMC.counter)
        FROM
            (
            SELECT dmc.instance_id as instance, MAX(dmc.counter) as counter, filter as filter_partition
            FROM {dmc_table} as dmc, (SELECT T.a as filter FROM ({filter_list}) as T)
            WHERE filter LIKE dmc.partition || '%'
            GROUP BY instance, filter_partition
            ) as PMC
        GROUP BY PMC.instance
        HAVING {count} = COUNT(PMC.filter_partition)
        """.format(dmc_table=cls._meta.db_table,
                   filter_list=condition,
                   count=len(filters))

        with connection.cursor() as cursor:
            cursor.execute(filter_max_calculation)
            return dict(cursor.fetchall())