Message-ID: <3DB674CD.50404@klaster.net>
Date: Wed, 23 Oct 2002 12:07:09 +0200
From: Tomasz Myrta <jasiek@klaster.net>
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To: pgsql-sql@postgresql.org
Subject: sub-select with aggregate
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Hi
I want to perform query looking like this:

select
  user_id,
  a/sum_a as percent_a,
  b/sum_b as percent_b
from
  users join
  (select
    group_id,
    sum(a) as sum_a,
    sum(b) as sum_b
   from users group by group_id) X using (group_id)
where group_id=3;

This query works, but very slow. Subquery with aggregate is performed 
for all table rows instead of group_id=3.

I wish I could write it like this, but it doesn't work at all:
select
  user_id,
  a/sum_a as percent_a,
  b/sum_b as percent_b
from
  users U,
  (select
    sum(a) as sum_a,
    sum(b) as sum_b
   from users where group_id=U.group_id) X
where group_id=3;

I don't want to make it as single query with "group by", because it has 
a lot of fields and "group by" would be very long.

Regards,
Tomasz Myrta