Re: [PATCH] Enforce that INSERT...RETURNING preserves the order of multi rows

At 2012-10-17 09:56:22 -0400, tgl(at)sss(dot)pgh(dot)pa(dot)us wrote:
>
> > Clarify that in the documentation, and also write a test case
> > that will prevent us from breaking the rule in the future.
>
> I don't believe this is a good idea in the slightest. Yeah, the
> current implementation happens to act like that, but there is no
> reason that we should make it guaranteed behavior.

I always thought it *was* guaranteed, and I've encountered code written
by other people who were obviously under the same impression: take some
strings (e.g. flag names), use "insert … returning id", map the ids back
to the names, and use the values in further inserts into other tables
("flag_id foreign key references flags").

I know one could say "returning id, name", but there's certainly code
out there that doesn't do this.

I personally think the return order should be guaranteed; and if not,
then the documentation urgently needs some prominent warnings to tell
people that they should not assume this (for any variant of RETURNING).

-- Abhijit