In this paper, we discuss common optimization method of join queries within DDB system, and then give an intensive description of join optimization based on pre-test technology we applied, we make final analyses and conclusions of this paper at last.是什么意思_In this paper, we discuss common optimization method of join queries within DDB system, and then give an intensive description of join optimization based on pre-test technology we applied, we make final analyses and conclusions of this paper at last.在线翻译_英语_读音_用法_例句