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Re: Schema variables - new implementation for Postgres 15

Pavel Stehule <pavel.stehule@gmail.com>

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From: Pavel Stehule <pavel.stehule@gmail.com>
To: walther@technowledgy.de
Cc: Tom Lane <tgl@sss.pgh.pa.us>, 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: 2024-05-25T10:50:45Z
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.

so 25. 5. 2024 v 10:24 odesílatel <walther@technowledgy.de> napsal:

> 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;
>
>
It looks odd - It is not intuitive, it introduces new inconsistency inside
Postgres, or with solutions in other databases. No other database has a
similar rule, so users coming from Oracle, Db2, or MSSQL, Firebird will be
confused. Users that use PL/pgSQL will be confused.

Regards

Pavel


>
> Best,
>
> Wolfgang
>