Re: Support UPDATE table SET(*)=...

From: Merlin Moncure <mmoncure(at)gmail(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Marko Tiikkaja <marko(at)joh(dot)to>, Atri Sharma <atri(dot)jiit(at)gmail(dot)com>, Marti Raudsepp <marti(at)juffo(dot)org>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Support UPDATE table SET(*)=...
Date: 2014-10-17 15:22:11
Message-ID: CAHyXU0y92ukn0jSpD36TGChgzK8=1WhiFvBeXDNtjRV5oHVwPg@mail.gmail.com
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On Fri, Oct 17, 2014 at 10:16 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Marko Tiikkaja <marko(at)joh(dot)to> writes:
>> local:marko=#* create table foo(f int);
>> CREATE TABLE
>> local:marko=#* update foo f set f=1;
>> UPDATE 0
>
>> This query would change meaning with your suggestion.
>
> I think it wouldn't; Merlin is proposing that f would be taken as the
> field name. A more realistic objection goes like this:
>
> create table foo(f int, g int);
> update foo x set x = (1,2); -- works
> alter table foo add column x int;
> update foo x set x = (1,2,3); -- no longer works
>
> It's not a real good thing if a column addition or renaming can
> so fundamentally change the nature of a query.

That's exactly how SELECT works. I also dispute that the user should
be surprised in such cases.

merlin

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