Re: Implement targetlist SRFs using ROWS FROM() (was Changed SRF in targetlist handling)

On Fri, Sep 2, 2016 at 9:25 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Andres Freund <andres@anarazel.de> writes:
>> Oh, and we've previously re-added that based on
>> complaints. C.f. d543170f2fdd6d9845aaf91dc0f6be7a2bf0d9e7 (and others
>> IIRC).
>
> That one wasn't about row order per se, but I agree that people *will*
> bitch if we change the behavior, especially if we don't provide a way
> to fix it.

They might also bitch if you add any overhead to put rows in a
specific order when they subsequently sort the rows into some
different order.  You might even destroy an order that would have
allowed a sort step to be skipped, so you would pay twice -- once
to put them into some "implied" order and then to sort them back
into the order they would have had without that extra effort.

> ORDER BY is not a useful suggestion when there is nothing
> you could order by to get the old behavior.

I'm apparently missing something, because I see a column with the
header "generate_series" in the result set.

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company