db=MySQLdb.connect(host="127.0.0.1",user="USER",passwd="123456",db="hive",charset="utf8" cursorclass=cursors.SSCursor) cursor = db.cursor() n = cursor.execute("select * from table") for row in cursor.fetchall(): for r in row: print r select出来的数据需要一次性加载到内存吗?