在类别内进行排序并将此配置单元表限制为5 [英] sort within category and limit 5 for this hive table

问题描述

我有一个配置表格A，它有以下列：

I have a hive table A that has the following column

USER   ITEM    SCORE
U1      I1       S1
U1      I2       S2
...................

我想要的是一个表格B这样的格式

What I want is a table B such a format

USER    ITEMS    #ITEMS is an array
 U1     [I2,I3,...]   # items are sorted according to score in descending and limit 5

对于用户而言，只有少于5个项目，只需将项目按降序排列即可。

for users have less than 5 items, just put the array with items in descending order.

推荐答案

这：

should be something like this :

select USER,collect_set(ITEM) from (
    select USER, ITEM,row_number () over (partition by USER order by SCORE desc) RN 
    from A
) t1
where RN <= 5
group by USER;

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