Horton

Re: Schema variables - new implementation for Postgres 15

Pavel Stehule <pavel.stehule@gmail.com>

View thread
From: Pavel Stehule <pavel.stehule@gmail.com>
To: Wolfgang Walther <walther@technowledgy.de>
Cc: Dmitry Dolgov <9erthalion6@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Peter Eisentraut <peter@eisentraut.org>, Alvaro Herrera <alvherre@alvh.no-ip.org>, 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: 2024-05-31T13:11:21Z
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.

pá 31. 5. 2024 v 15:02 odesílatel Pavel Stehule <pavel.stehule@gmail.com>
napsal:

>
>
> pá 31. 5. 2024 v 13:37 odesílatel Wolfgang Walther <
> walther@technowledgy.de> napsal:
>
>> Pavel Stehule:
>> >     But in this case you could make variables and tables share the same
>> >     namespace, i.e. forbid creating a variable with the same name as an
>> >     already existing table.
>> >
>> >
>> > It helps, but not on 100% - there is a search path
>>
>
>> I think we can ignore the search_path for this discussion. That's not a
>> problem of variables vs tables, but just a search path related problem.
>> It is exactly the same thing right now, when you create a new table x(x)
>> in a schema which happens to be earlier in your search path.
>>
>
> I don't think it is a valid argument - search_path is there, and we cannot
> ignore it, because it allows just one case.
>
> And the need to use a variable in FROM clause introduces implicit
> unpacking or inconsistency with current work with composite's types, so I
> am more sure this way is not good.
>

The session variables can be used in queries, but should be used in
PL/pgSQL expressions, and then the mandatory usage in FROM clause will do
lot of problems and unreadable code like

DO $$
BEGIN
  RAISE NOTICE '% %', (SELECT x FROM x), (SELECT a,b FROM y);

END
$$

This requirement does variables unusable in PL



>
>
>
>>
>> The objection to the proposed approach for variables was that it would
>> introduce *new* ambiguities, which Alvaro's suggestion avoids.
>>
>> Best,
>>
>> Wolfgang
>>
>