I considered this, however the subquery is generated by an ORM. I
wanted to separate it.
Also the whole join affects many rows. I thought it's cheaper to
preselect them inside the subquery then do the join. I am not sure.
Explain analyze is my good friend but in this case I prefer to ask.
#
On 11/19/2010 03:21 AM, Thom Brown wrote:
You should always use ORDER BY on the outer-most part of the query
since that's what will be finally returning your data. Don't bother
with ordering sub-selects.
I definiatelly have to use the "order by" inside for two reasons.
When "distinct on (x)"
On 19 November 2010 01:36, Mage wrote:
> Hello,
>
> (I googled and read docs before sending this e-mail).
>
> Is it necessary to use order by twice (inside and outside) to get the proper
> order if I have an ordered subqery in a join?
>
> select * from (select distinct on (b_id) * from
Hello,
(I googled and read docs before sending this e-mail).
Is it necessary to use order by twice (inside and outside) to get the
proper order if I have an ordered subqery in a join?
select * from (select distinct on (b_id) * from a order by b_id, id) sub
left join b on b.id = s
