你也可以使用分析函数和size(collect_set)来计算不同的人。这将允许消除连接，并且如果每个问题的不同人的数量不是太大的话（collect_set产生的数组可以容纳在内存中），就可以正常工作。

select qa.question_id, qa.answer_id, 
       qa.num_persons * 100.0 / size(qa.question_persons) as Percentage
from (select question_id, answer_id, 
             count(*) over (partition by question_id, answer_id) as num_persons,
             collect_set(person_id) over(partition by question_id) as question_persons
      from t
     ) qa;

如果我理解正确的话，你想要选择某个特定问题/答案组合的人数除以选择该问题的人数。

select qa.*, qa.num_persons * 100.0 / q.num_persons
from (select question_id, answer_id, count(*) as num_persons
      from t
      group by question_id, answer_id
     ) qa join
     (select question_id, count(distinct person_id) as num_persons
      from t
      group by question_id
     ) q
     on qa.question_id = q.question_id;

我对prestodb不熟悉，但下面是一个sql脚本，它的结果与你发布的内容相同。
`2.0'是人的数量。你可能想先选择它，然后把它存储在一个可移动的容器中。

select 
     question_id, answer_id, (count(answer_id)/2.0) * 100.0
from Sample
group by question_id, answer_id
order by question_Id, answer_id