Horton

Re: Schema variables - new implementation for Postgres 15

Wolfgang Walther <walther@technowledgy.de>

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From: walther@technowledgy.de
To: Pavel Stehule <pavel.stehule@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>
Cc: Peter Eisentraut <peter@eisentraut.org>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Dmitry Dolgov <9erthalion6@gmail.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>, Sergey Shinderuk <s.shinderuk@postgrespro.ru>, Tomas Vondra <tomas.vondra@enterprisedb.com>, Julien Rouhaud <rjuju123@gmail.com>, dean.a.rasheed@gmail.com, er@xs4all.nl, joel@compiler.org, pgsql-hackers@lists.postgresql.org
Date: 2024-05-25T08:24:41Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Allow underscores in integer and numeric constants.

  2. Remove special outfuncs/readfuncs handling of RangeVar.catalogname.

  3. Remove extra space from dumped ALTER DEFAULT PRIVILEGES.

  4. Create FKs properly when attaching table as partition

  5. psql: improve tab-complete's handling of variant SQL names.

Pavel Stehule:
> Sure there is more possibilities, but I don't want to lost the 
> possibility to write code like
> 
> CREATE TEMP VARIABLE _x;
> 
> LET _x = 'hello';
> 
> DO $$
> BEGIN
>    RAISE NOTICE '%', _x;
> END;
> $$;
> 
> So I am searching for a way to do it safely, but still intuitive and 
> user friendly.

Maybe a middle-way between this and Alvaro's proposal could be:

Whenever you have a FROM clause, a variable must be added to it to be 
accessible.  When you don't have a FROM clause, you can access it directly.

This would make the following work:

RAISE NOTICE '%', _x;

SELECT _x;

SELECT tbl.*, _x FROM tbl, _x;

SELECT tbl.*, (SELECT _x) FROM tbl, _x;

SELECT tbl.*, (SELECT _x FROM _x) FROM tbl;


But the following would be an error:

SELECT tbl.*, _x FROM tbl;

SELECT tbl.*, (SELECT _x) FROM tbl;


Best,

Wolfgang