FYI, the question has been answered in user-zh ML. lec ssmi <shicheng31...@gmail.com> 于2020年4月23日周四 下午2:57写道：
> Hi: > Is there an aggregation operation or window operation, the result is > with retract characteristics? > > -- Benchao Li School of Electronics Engineering and Computer Science, Peking University Tel:+86-15650713730 Email: libenc...@gmail.com; libenc...@pku.edu.cn
