Re: Is postgres able to share sorts required by common partition window functions?

Hi Michael,

I simplified the real query before posting it here and I now realize that I
oversimplified things.

Unfortunately the real query cannot be re-written with a group by.

Some of the window functions are more complex with order by clause using
complex expressions involving multiple columns.

The following example would be more realistic:

select distinct
c1,
first_value(c2) OVER (PARTITION BY c1 order by c2, c4) AS c2,
first_value(c3) OVER (PARTITION BY c1 order by coalesce(c4, '000'), c3)
AS c3
from
t;

On Mon, Jul 6, 2020 at 9:55 PM Michael Lewis <mlewis(at)entrata(dot)com> wrote:

> Does this give the same result and do the optimization you want?
>
> select
> c1,
> min(c2) AS c2,
> min(c3) AS c3,
> min(c4) AS c4
> from
> t
> group by
> c1;
>
>>