Question

我有一个事件表，其中包含以下列user_id，points，created。我需要的是获得给定user_id的给定月份，总积分和总排名的所有积分。我需要在单个查询中执行此操作，从而导致以下尝试：

select
    e.user_id,
    sum(e.points) as total_points,
    (select sum(points) from event where user_id = 1 and extract(month from created) = 1) as month_points,
    (select rank from (select user_id as id, rank() over (order by sum(points) desc) from event group by user_id) as rank where id = 1)
from
    event pte
where
    e.user_id = 1
group by
    e.user_id
;

我想问的是：

此查询可以缓慢吗？
可以用其他方式做得更好吗？
rank功能是否足够可靠还是被误用了？

Answer 1

假设postgresql版本大于或等于9.4，您可以使用聚合filter子句来避免month_points和rank的子选择：

select * from
    (select
        e.user_id,
        sum(e.points) as total_points,
        sum(points) filter (where extract(month from created) = 1) as month_points,
        rank() over (order by sum(points) desc)
    from
        event e
    group by
        e.user_id
    ) as inner_query
where user_id = 1;

PostgreSQL查询性能和变化

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