Select from SUM() of multiple columns and join in postgreSQL

Question

I have a table called DETAILS which has 5 numeric columns DETAILS(id, key2, key3, num1, num2, num3, num4, num5). Combination of id, key2 and key3 is the primary key. Each id may have multiple rows.

My requirement is to get top 10 SUM values of each column grouped by id as below.

select   id
        ,sum(num1) val1
 from details   
group by id
order by sum(num1) desc nulls last
limit 10;

select   id
        ,sum(num2) val2
 from details  
group by id
order by sum(num2) desc nulls last
limit 10;

select   id
        ,sum(num3) val3
 from details   
group by id
order by sum(num3) desc nulls last
limit 10;

select   id
        ,sum(num4) val4
 from details   
group by id
order by sum(num4) desc nulls last
limit 10;

select   id
        ,sum(num5) val5
 from details
group by id
order by sum(num5) desc nulls last
limit 10;

I need the above results to be combined based on the id as below

id, sum(num1), sum(num2), sum(num3), sum(num4), sum(num5)

Lets say the first query returns

[{id: 1, val1: 50}, {id: 2, val1: 60}, {id: 3, val1: 70}]

the second query returns

[{id: 3, val2: 150}, {id: 4, val2: 160}, {id: 3, val2: 170}]

The result should be

[
{id: 1, val1: 50, val2: null}, 
{id: 2, val1: 60, val2: null}, 
{id: 3, val1: 70, val2: 150},
{id: 4, val1: null, val2: 160},
{id: 5, val1: null, val2: 170},
]

Is this possible with single query using join or something? If so how do I achieve this with a optimised query?

Answer 1

I think that you want a FULL OUTER JOIN of all 5 queries:

with
  cte1 as (
    select id, sum(num1) val1 from details   
    group by id
    order by sum(num1) desc nulls last limit 10
  ),
  cte2 as (
    select id, sum(num2) val2 from details   
    group by id
    order by sum(num2) desc nulls last limit 10
  ),  
  cte3 as (
    select id, sum(num3) val3 from details   
    group by id
    order by sum(num3) desc nulls last limit 10
  ),  
  cte4 as (
    select id, sum(num4) val4 from details   
    group by id
    order by sum(num4) desc nulls last limit 10
  ),  
  cte5 as (
    select id, sum(num5) val5 from details   
    group by id
    order by sum(num5) desc nulls last limit 10
  )
select coalesce(c1.id, c2.id, c3.id, c4.id, c5.id) id,
       c1.val1, c2.val2, c3.val3, c4.val4, c5.val5
from cte1 c1
full outer join cte2 c2 on c2.id = c1.id
full outer join cte3 c3 on c3.id = c2.id
full outer join cte4 c4 on c4.id = c3.id
full outer join cte5 c5 on c5.id = c4.id