Sql 在presto中优化窗口查询

我有一个表，其中包含诸如user_id、col1、col2、col3、updated_at、is_deleted、day等字段

当前查询如下所示-

 SELECT DISTINCT
    user_id,
    first_value(col1) ignore nulls OVER (partition BY user_id 
 ORDER BY
    updated_at DESC rows BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED following) AS col1,
    first_value(col2) ignore nulls OVER (partition BY user_id 
 ORDER BY
    updated_at DESC rows BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED following) AS col2,
    first_value(col3) ignore nulls OVER (partition BY user_id 
 ORDER BY
    updated_at DESC rows BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED following) AS col3,
    bool_or(is_deleted) ignore nulls OVER (partition BY user_id 
 ORDER BY
    updated_at DESC rows BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED following) AS is_deleted 
 FROM
    my_table
 WHERE
    day >= '2021-05-25'

基本上，对于每个用户id，我需要每个列的最新（第一个）值。由于每个值列都可以为null，因此我必须多次运行相同的窗口查询（对于每个列）。 目前，66%的时间都花在窗口上。

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有什么优化的方法吗？

似乎您想要这样：

select * from (
  select * , row_number() over (partition by user_id ORDER BY updated_at DESC) rn 
  from my_table
  where day >= '2021-05-25'
) t 
where rn = 1

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它可以返回OP希望避免的空值。