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From: Pavel Stehule <pavel.stehule@gmail.com>
To: remi duval <remi.duval@cheops.fr>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: proposal: schema variables
Date: Thu, 27 Feb 2020 15:37:48 +0100
Message-ID: <CAFj8pRC9H8s3=Twpk4e+As6Sz7NrceynEKsupg5JLNpVBe4sqQ@mail.gmail.com> (raw)
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Hi


> 3) Any way to define CONSTANTs ?
> We already talked a bit about this subject and also Gilles Darold
> introduces it in this mailing-list topic but I'd like to insist on it.
> I think it would be nice to have a way to say that a variable should not
> be changed once defined.
> Maybe it's hard to implement and can be implemented later, but I just want
> to know if this concern is open.
>

I played little bit with it and I didn't find any nice solution, but maybe
I found the solution. I had ideas about some variants, but almost all time
I had a problem with parser's shifts because all potential keywords are not
reserved.

last variant, but maybe best is using keyword WITH

So the syntax can looks like

CREATE [ TEMP ] VARIABLE varname [ AS ] type [ NOT NULL ] [ DEFAULT
expression ] [ WITH [ OPTIONS ] '(' ... ')' ] ]

What do you think about this syntax? It doesn't need any new keyword, and
it easy to enhance it.

CREATE VARIABLE foo AS int DEFAULT 10 WITH OPTIONS ( CONSTANT);

?

Regards

Pavel

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  Subject: Re: proposal: schema variables
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