Re: Idea: Add first() and last() aggregate functions to the main release

On Sat, 11 Mar 2023 at 23:38, Ben Clements <benhasgonewalking(at)gmail(dot)com>
wrote:

> Idea/request for enhancement:
>
> Add the first() and last() aggregate functions to the main release (CREATE
> EXTENSION first_last_agg).
>
> Use Case: PostgreSQL equivalent to Oracle's MAX(...) KEEP (DENSE_RANK
> FIRST/LAST ORDER BY ...) <https://dba.stackexchange.com/a/324646/100880>
> (https://dba.stackexchange.com/a/324646/100880)
>
> GitHub: https://github.com/wulczer/first_last_agg
>
> Reason: As a non-dba, I can’t install additional modules like
> first_last_agg.
>

For what it's worth, I support the inclusion of first() and last() in the
main release. It makes queries involving multiple aggregate functions a lot
simpler. Most hosted services only allow official contrib modules.
The module has been around for more than 10 years now. First on
https://www.pgxn.org/dist/first_last_agg, then on
https://github.com/wulczer/first_last_agg. And it's been available from
apt.postgresql.org for a long time now.
Related questions pop up on Stackoverflow every now and then.
(I don't see anything related in the Postgres Todo, yet.)

The implementation in the additional module first_last_agg looks very
simple and straight-forward. Might be an easy task to incorporate into
mainline Postgres. But my C foo is just not good enough to judge whether
the implementation is ideal.

Regards
Erwin