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From: Pavel Stehule <pavel.stehule@gmail.com>
Date: Thu, 27 Feb 2020 15:37:48 +0100
Message-ID: 
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Subject: Re: proposal: schema variables
To: remi duval <remi.duval@cheops.fr>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
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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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<div dir=3D"ltr"><div dir=3D"ltr"><br></div><div>Hi</div><div><br></div><di=
v><div class=3D"gmail_quote"><div class=3D"gmail_quote"><blockquote class=
=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rg=
b(204,204,204);padding-left:1ex">
<br>
3) Any way to define CONSTANTs ?<br>
We already talked a bit about this subject and also Gilles Darold introduce=
s it in this mailing-list topic but I&#39;d like to insist on it.<br>
I think it would be nice to have a way to say that a variable should not be=
 changed once defined.<br>
Maybe it&#39;s hard to implement and can be implemented later, but I just w=
ant to know if this concern is open.<br></blockquote><div><br></div>I playe=
d little bit with it and I didn&#39;t find any nice solution, but maybe I f=
ound the solution. I had ideas about some variants, but almost all time I h=
ad a problem with parser&#39;s shifts because all potential keywords are no=
t reserved.</div><div class=3D"gmail_quote"><br></div><div class=3D"gmail_q=
uote">last variant, but maybe best is using keyword WITH</div><div class=3D=
"gmail_quote"><br></div><div class=3D"gmail_quote">So the syntax can looks =
like</div><div class=3D"gmail_quote"><br></div><div class=3D"gmail_quote">C=
REATE [ TEMP ] VARIABLE varname [ AS ] type [ NOT NULL ] [ DEFAULT expressi=
on ] [ WITH [ OPTIONS ] &#39;(&#39; ... &#39;)&#39; ] ] <br></div><div clas=
s=3D"gmail_quote"><br></div><div class=3D"gmail_quote">What do you think ab=
out this syntax? It doesn&#39;t need any new keyword, and it easy to enhanc=
e it.</div><div class=3D"gmail_quote"><br></div><div class=3D"gmail_quote">=
CREATE VARIABLE foo AS int DEFAULT 10 WITH OPTIONS ( CONSTANT);<br></div><d=
iv class=3D"gmail_quote"><div><br></div><div>?</div><div><br></div><div>Reg=
ards</div><div><br></div><div>Pavel<br></div><div><br></div><br></div><bloc=
kquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:=
1px solid rgb(204,204,204);padding-left:1ex">
</blockquote></div></div></div>

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