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From: David Christensen <david@pgguru.net>
Date: Tue, 23 Jul 2024 08:22:55 -0500
Message-ID: <CAHM0NXgVfYYt1Yw6iVqGY9PZ=dVPe6HhEByH9uD-H-AA0z_1Zg@mail.gmail.com>
Subject: Re: [PATCH] GROUP BY ALL
To: "David G. Johnston" <david.g.johnston@gmail.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
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On Mon, Jul 22, 2024 at 4:34=E2=80=AFPM David G. Johnston
<david.g.johnston@gmail.com> wrote:
>
> On Mon, Jul 22, 2024 at 1:55=E2=80=AFPM David Christensen <david@pgguru.n=
et> wrote:
>>
>> I see that there'd been some chatter but not a lot of discussion about
>> a GROUP BY ALL feature/functionality.  There certainly is utility in
>> such a construct IMHO.
>>
>> Still need some docs; just throwing this out there and getting some feed=
back.
>>
>
> I strongly dislike adding this feature.  I'd only consider supporting it =
if it was part of the SQL standard.
>
> Code is written once and read many times.  This feature caters to the wri=
ter, not the reader.  And furthermore usage of this is prone to be to the w=
riter's detriment as well.

I'd say this feature (at least for me) caters to the investigator;
someone who is interactively looking at data hence why it would cater
to the writer.  Consider acquainting yourself with a large table that
has a large number of annoying-named fields where you want to look at
how different data is correlated or broken-down.  Something along the
lines of:

SELECT last_name, substring(first_name,1,1) as first_initial,
income_range, count(*) FROM census_data GROUP BY ALL;

If you are iteratively looking at things, adding or removing fields
from your breakdown, you only need to change it in a single place, the
tlist.  Additionally, expressions can be used transparently without
needing to repeat them.  (Yes, in practice, I'd often use GROUP BY 1,
2, say, but if you add more fields to this you need to edit in
multiple places.)

David