Обсуждение: BUG #5841: rank()+1 fails, 1+rank() succeeds

The following bug has been logged online:

Bug reference:      5841
Logged by:          Jeff Turner
Email address:      jeff@biccard.com
PostgreSQL version: 9.0.1
Operating system:   Ubuntu 10.10
Description:        rank()+1 fails, 1+rank() succeeds
Details:

Given a table:

create table t (foo varchar, bar integer);
insert into t values ('a', 1), ('b', 2), ('c', 1);

This query succeeds:

select *, 1+rank() over (partition by bar) from t;

However, replace '1+rank()' with 'rank()+1' and it fails:

test=# select *, rank()+1 over (partition by bar) from t;
ERROR:  syntax error at or near "over"
LINE 1: select *, rank()+1 over (partition by bar) from t;

Excerpts from Jeff Turner's message of lun ene 17 07:34:29 -0300 2011:

> test=# select *, rank()+1 over (partition by bar) from t;
> ERROR:  syntax error at or near "over"
> LINE 1: select *, rank()+1 over (partition by bar) from t;

The "over" stuff is part of the expression; you can't add the +1 in the
middle.  This works:

select *, rank() over (partition by bar) + 1 from t;

--
Álvaro Herrera <alvherre@commandprompt.com>
The PostgreSQL Company - Command Prompt, Inc.
PostgreSQL Replication, Consulting, Custom Development, 24x7 support

Thanks for clarifying. I've submitted a note on the interactive
version of the docs, and attached a small patch to make explicit that
a window function is followed _immediately_ by an OVER clause, as the
syntax[1] indicates.

Regards,
Jeff


[1]
http://www.postgresql.org/docs/current/static/sql-expressions.html#SYNTAX-WINDOW-FUNCTIONS

Quoting Alvaro Herrera <alvherre@commandprompt.com>:

> Excerpts from Jeff Turner's message of lun ene 17 07:34:29 -0300 2011:
>
>> test=# select *, rank()+1 over (partition by bar) from t;
>> ERROR:  syntax error at or near "over"
>> LINE 1: select *, rank()+1 over (partition by bar) from t;
>
> The "over" stuff is part of the expression; you can't add the +1 in the
> middle.  This works:
>
> select *, rank() over (partition by bar) + 1 from t;
>
> --
> Álvaro Herrera <alvherre@commandprompt.com>
> The PostgreSQL Company - Command Prompt, Inc.
> PostgreSQL Replication, Consulting, Custom Development, 24x7 support
>

On Tue, Jan 18, 2011 at 6:19 AM,  <jeff@biccard.com> wrote:
> Thanks for clarifying. I've submitted a note on the interactive version of
> the docs, and attached a small patch to make explicit that a window function
> is followed _immediately_ by an OVER clause, as the syntax[1] indicates.

I've committed the first hunk of this patch, as I think it's useful
and innocuous.  The second half looks like bad grammar to me.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company