Feedback-ID: id9394477:Fastmail
MIME-Version: 1.0
Date: Fri, 05 Sep 2025 17:02:53 -0700
From: "Jason Tiller" <jason@starnull.net>
To: pgsql-docs@lists.postgresql.org
Message-Id: <6cc77ca1-54e7-4e8d-a69e-6159fa497cb7@app.fastmail.com>
In-Reply-To: <1529415.1757107022@sss.pgh.pa.us>
References: <175702516430.356921.959597202664413151@wrigleys.postgresql.org>
 <1529415.1757107022@sss.pgh.pa.us>
Subject: Re: SELECT List with/without parentheses
Content-Type: text/plain
Content-Transfer-Encoding: 7bit
Archived-At: 
 <https://www.postgresql.org/message-id/6cc77ca1-54e7-4e8d-a69e-6159fa497cb7%40app.fastmail.com>
Precedence: bulk

Hi, Tom,

Thanks for your feedback! I'm a SQL newbie and the "implicit row constructor" syntax was an unwelcome surprise. I guess painful debugging is one way to cement a concept...

Seems like this is a nothing-burger and probably has no place in the PostgreSql documentation. Although I feel like the "principle of least surprise" has been violated here. :/

I appreciate the info!

---Jason

On Fri, Sep 5, 2025, at 2:17 PM, Tom Lane wrote:
> PG Doc comments form <noreply@postgresql.org> writes:
>> There is no mention of the difference in PostgreSql behavior if the select
>> list of columns is surrounded by parentheses or not.
>
> What you've written there is an implicit row constructor, that is
> "(a,b,...)" is taken as "ROW(a,b,...)".  These are documented at [1],
> but it would be quite unwieldy to point out the possibility of this
> for every context in which it could be written.
>
> Personally I think implicit row constructors were one of the SQL
> committee's worst ideas, precisely because of the surprise factor.
> But it's in the standard so we're stuck with it.
>
> 			regards, tom lane
>
> [1] 
> https://www.postgresql.org/docs/current/sql-expressions.html#SQL-SYNTAX-ROW-CONSTRUCTORS

On Fri, Sep 5, 2025, at 2:17 PM, Tom Lane wrote:
> PG Doc comments form <noreply@postgresql.org> writes:
>> There is no mention of the difference in PostgreSql behavior if the select
>> list of columns is surrounded by parentheses or not.
>
> What you've written there is an implicit row constructor, that is
> "(a,b,...)" is taken as "ROW(a,b,...)".  These are documented at [1],
> but it would be quite unwieldy to point out the possibility of this
> for every context in which it could be written.
>
> Personally I think implicit row constructors were one of the SQL
> committee's worst ideas, precisely because of the surprise factor.
> But it's in the standard so we're stuck with it.
>
> 			regards, tom lane
>
> [1] 
> https://www.postgresql.org/docs/current/sql-expressions.html#SQL-SYNTAX-ROW-CONSTRUCTORS