Re: Allow WindowFuncs prosupport function to use more optimal WindowClause options

On 10/20/22 22:02, David Rowley wrote:
> On Thu, 13 Oct 2022 at 13:34, David Rowley <dgrowleyml(at)gmail(dot)com> wrote:
>> So it looks like the same can be done for rank() and dense_rank() too.
>> I've added support for those in the attached.
>
> The attached adds support for percent_rank(), cume_dist() and ntile().

Shouldn't it be able to detect that these two windows are the same and
only do one WindowAgg pass?

explain (verbose, costs off)
select row_number() over w1,
lag(amname) over w2
from pg_am
window w1 as (order by amname),
w2 as (w1 rows unbounded preceding)
;

QUERY PLAN
-----------------------------------------------------------------
WindowAgg
Output: (row_number() OVER (?)), lag(amname) OVER (?), amname
-> WindowAgg
Output: amname, row_number() OVER (?)
-> Sort
Output: amname
Sort Key: pg_am.amname
-> Seq Scan on pg_catalog.pg_am
Output: amname
(9 rows)

--
Vik Fearing