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

On Oct 17, 2014 6:16 PM, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> 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.

I think a significant use case for this feature is when you already have a
row-value and want to persist it in the database, like you can do with
INSERT:
insert into foo select * from populate_record_json(null::foo, '{...}');

In this case the opposite is true: requiring explicit column names would
break the query if you add columns to the table. The fact that you can't
reasonably use populate_record/_json with UPDATE is a significant omission.
IMO this really speaks for supporting shorthand whole-row assignment,
whatever the syntax.

Regards,
Marti