Re: Improve "3.5. Window Functions" tutorial

On Fri, Oct 2, 2026 at 3:40 AM David G. Johnston <david(dot)g(dot)johnston(at)gmail(dot)com>
wrote:

> On Wednesday, September 30, 2026, PG Doc comments form <
> noreply(at)postgresql(dot)org> wrote:
>
>> The following documentation comment has been logged on the website:
>>
>> Page: https://www.postgresql.org/docs/18/tutorial-window.html
>> Description:
>>
>> Hi! I would like to propose improvements on the "3.5. Window Functions"
>> tutorial.
>>
>> Wording may be improved ("scoped"), I think the added paragraph links the
>> existing ones providing more meaning.
>>
>
> I’m in agreement with this page being in need of improvement. I’m not all
> that comfortable with this particular proposal. It adds some of its own
> concerns and doesn’t remove some existing ones.
>

OK

> As an aside - recent comments about the undesirability were made - and
> while I’m accepting of their usage generally this one seems like a good
> candidate for removal if we do update this page.
>

> My biggest qualm is the wording that makes it sound like a window frame is
> an option in lieu of looking at the partition when there is always some
> default frame in place.
>

"Window functions perform calculations on a subset of rows of a query for
each row of it, That subset is called the window frame, and it is
constructed on a per-row basis. The query rows are first partitioned with a
provided criteria and may be refined further if the function supports it.
After the determination of the subset (the window frame), calculations are
performed on them and the result is provided for the row."

Do you think that is an accurate definition of window function? If so (or
after the construction of it), the article should be adjusted to be built
on that.

I find the article fuzzy about it. It goes with something like "After you
define a partition, if you supply ORDER_BY, then the window is narrowed and
can be controlled with... BUT this only works if function supports it" and
after reading, I find it difficult to produce a precise idea of it.

>
> David J.
>
>

On Fri, Oct 2, 2026 at 3:40 AM David G. Johnston <david(dot)g(dot)johnston(at)gmail(dot)com>
wrote:

> On Wednesday, September 30, 2026, PG Doc comments form <
> noreply(at)postgresql(dot)org> wrote:
>
>> The following documentation comment has been logged on the website:
>>
>> Page: https://www.postgresql.org/docs/18/tutorial-window.html
>> Description:
>>
>> Hi! I would like to propose improvements on the "3.5. Window Functions"
>> tutorial.
>>
>> Wording may be improved ("scoped"), I think the added paragraph links the
>> existing ones providing more meaning.
>>
>
> I’m in agreement with this page being in need of improvement. I’m not all
> that comfortable with this particular proposal. It adds some of its own
> concerns and doesn’t remove some existing ones.
>
> As an aside - recent comments about the undesirability were made - and
> while I’m accepting of their usage generally this one seems like a good
> candidate for removal if we do update this page.
>
> My biggest qualm is the wording that makes it sound like a window frame is
> an option in lieu of looking at the partition when there is always some
> default frame in place.
>
> David J.
>
>