Jin Jin - 27 days ago 9
SQL Question

sort within category and limit 5 for this hive table

I have a hive table A that has the following column

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


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


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

Answer Source

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;