| From: | Alexander Korotkov <aekorotkov(at)gmail(dot)com> |
|---|---|
| To: | Andrei Lepikhov <a(dot)lepikhov(at)postgrespro(dot)ru> |
| Cc: | Richard Guo <guofenglinux(at)gmail(dot)com>, Pavel Borisov <pashkin(dot)elfe(at)gmail(dot)com>, vignesh C <vignesh21(at)gmail(dot)com>, PostgreSQL Developers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com>, Teodor Sigaev <teodor(at)sigaev(dot)ru>, David Rowley <dgrowleyml(at)gmail(dot)com>, "a(dot)rybakina" <a(dot)rybakina(at)postgrespro(dot)ru>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Subject: | Re: POC: GROUP BY optimization |
| Date: | 2024-01-19 14:21:48 |
| Message-ID: | CAPpHfdtNnX9PYmgEsh9DXYws2Px6UJhH5kYUxsg3hu-zJTYuWw@mail.gmail.com |
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| Lists: | pgsql-hackers |
Hi!
I've applied your changes with minor editing, thank you.
On Thu, Jan 18, 2024 at 11:49 AM Andrei Lepikhov
<a(dot)lepikhov(at)postgrespro(dot)ru> wrote:
> >> * Part of the work performed in this patch overlaps with that of
> >> preprocess_groupclause. They are both trying to adjust the ordering of
> >> the GROUP BY keys to match ORDER BY. I wonder if it would be better to
> >> perform this work only once.
> >
> > Andrei, could you take a look.
> As I see, the PathKeyInfo list often contains duplicated pathkeys,
> coming from either sort_pathkeys or path->pathkeys orderings. So, I can
> propose to check duplicates each time (see step2.txt in attachment).
Actually I asked to recheck if we can cut some part of
preprocess_groupclause() given that we're reordering the pathkeys
later. It seems that we can remove everything except the work with a
grouping set. I've done this in the revised patchset.
I'm going to push this if there are no objections.
------
Regards,
Alexander Korotkov
| Attachment | Content-Type | Size |
|---|---|---|
| 0002-Explore-alternative-orderings-of-group-by-p-20240119.patch | application/octet-stream | 43.0 KB |
| 0001-Generalize-common-code-of-adding-sort-befor-20240119.patch | application/octet-stream | 9.1 KB |
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