Re: ExecTypeSetColNames is fundamentally broken

On Tue, Dec 7, 2021 at 12:30 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> If we consider that the alias renames the columns "for all purposes",
> how is it okay for f() to select the "a" column?

I'd say it isn't.

> Another way to phrase the issue is that the column names seen
> by f() are currently different from those seen by row_to_json():
>
> regression=# select row_to_json(t) from t as t(x,y);
> row_to_json
> -----------------
> {"x":11,"y":12}
> (1 row)
>
> and that seems hard to justify.

Yeah, I agree. The problem I have here is that, with your proposed
fix, it still won't be very consistent. True, row_to_json() and f()
will both see the unaliased column names ... but a straight select *
from t as t(x,y) will show the aliased names. That's unarguably better
than corrupting your data, but it seems "astonishing" in the POLA
sense.

--
Robert Haas
EDB: http://www.enterprisedb.com