Thread

1. remark regarding 4.2.13. Row Constructors

   The Post Office <noreply@postgresql.org> — 2026-06-08T07:42:45Z

   The following documentation comment has been logged on the website:
   
   Page: https://www.postgresql.org/docs/18/sql-expressions.html
   Description:
   
   Hi,
   
   in
   https://www.postgresql.org/docs/current/sql-expressions.html#SQL-SYNTAX-ROW-CONSTRUCTORS
   there is:
   "The key word ROW is optional when there is more than one expression in the
   list."
   I think it should be:
   "The key word ROW is optional when there are more than zero expressions in
   the list."
   
   Test Case:
   [postgres@lin5 ~]$ psql mydb
   psql (19beta1)
   Type "help" for help.
   
   mydb=# select (1);
    ?column?
   ----------
           1
   (1 row)
   
   mydb=# select (1,2);
     row
   -------
    (1,2)
   (1 row)
   
   mydb=# select ();
   ERROR:  syntax error at or near ")"
   LINE 1: select ();
                   ^
   mydb=# select row();
    row
   -----
    ()
   (1 row)
   
   mydb=#
   
   Regards
   Jochen
   
   
   
   
   

2. Re: remark regarding 4.2.13. Row Constructors

   Daniel Gustafsson <daniel@yesql.se> — 2026-06-09T08:06:20Z

   > On 8 Jun 2026, at 09:42, PG Doc comments form <noreply@postgresql.org> wrote:
   
   > in
   > https://www.postgresql.org/docs/current/sql-expressions.html#SQL-SYNTAX-ROW-CONSTRUCTORS
   > there is:
   > "The key word ROW is optional when there is more than one expression in the
   > list."
   > I think it should be:
   > "The key word ROW is optional when there are more than zero expressions in
   > the list."
   
   "more than zero" sounds a bit odd, my suggestion would be "The key word ROW is
   optional when there is one, or more, expressions in the list."
   
   --
   Daniel Gustafsson
   
   
   
   
   

3. Re: remark regarding 4.2.13. Row Constructors

   Tom Lane <tgl@sss.pgh.pa.us> — 2026-06-09T16:46:38Z

   Daniel Gustafsson <daniel@yesql.se> writes:
   >> On 8 Jun 2026, at 09:42, PG Doc comments form <noreply@postgresql.org> wrote:
   >> in
   >> https://www.postgresql.org/docs/current/sql-expressions.html#SQL-SYNTAX-ROW-CONSTRUCTORS
   >> there is:
   >> "The key word ROW is optional when there is more than one expression in the
   >> list."
   >> I think it should be:
   >> "The key word ROW is optional when there are more than zero expressions in
   >> the list."
   
   > "more than zero" sounds a bit odd, my suggestion would be "The key word ROW is
   > optional when there is one, or more, expressions in the list."
   
   More to the point, the statement is correct as written and either of
   these changes would make it wrong.  For example, both of these things
   produce a two-column composite value:
   
   postgres=# select row(1,2), (1,2);
     row  |  row  
   -------+-------
    (1,2) | (1,2)
   (1 row)
   
   postgres=# select pg_typeof(row(1,2)), pg_typeof((1,2));
    pg_typeof | pg_typeof 
   -----------+-----------
    record    | record
   (1 row)
   
   But adding more parentheses around a scalar value does not make
   it a composite value:
   
   postgres=# select row(1), (1), ((((1))));
    row | ?column? | ?column? 
   -----+----------+----------
    (1) |        1 |        1
   (1 row)
   
   postgres=# select pg_typeof(row(1)), pg_typeof((1)), pg_typeof(((((1)))));
    pg_typeof | pg_typeof | pg_typeof 
   -----------+-----------+-----------
    record    | integer   | integer
   (1 row)
   
   Maybe there is something we can do to make this clearer, but
   the above isn't it.
   
   			regards, tom lane