| From: | Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com> |
|---|---|
| To: | David Rowley <dgrowleyml(at)gmail(dot)com> |
| Cc: | Michael Paquier <michael(at)paquier(dot)xyz>, Zhihong Yu <zyu(at)yugabyte(dot)com>, "Andrey V(dot) Lepikhov" <a(dot)lepikhov(at)postgrespro(dot)ru>, Teodor Sigaev <teodor(at)sigaev(dot)ru>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, PostgreSQL Developers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: POC: GROUP BY optimization |
| Date: | 2022-08-18 07:29:43 |
| Message-ID: | a16ac766-f898-3299-28fd-5aabfa6f308d@enterprisedb.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
On 8/18/22 03:32, David Rowley wrote:
> On Thu, 18 Aug 2022 at 02:46, Tomas Vondra
> <tomas(dot)vondra(at)enterprisedb(dot)com> wrote:
>> So I don't think the current costing is wrong, but it certainly is more
>> complex. But the test does not test what it intended - I have two ideas
>> how to make it work:
>>
>> 1) increase the number of rows in the table
>>
>> 2) increase cpu_operator_cost (for that one test?)
>>
>> 3) tweak the costing somehow, to increase the cost a bit
>
> Why not, 4) SET parallel_setup_cost = 0; there are plenty of other
> places we do just that so we get a parallel plan without having to
> generate enough cost to drown out the parallel worker startup cost.
>
> Here are a couple of patches to demo the idea.
>
Yeah, that's an option too. I should have mentioned it along with the
cpu_operator_cost.
BTW would you mind taking a look at the costing? I think it's fine, but
it would be good if someone not involved in the patch takes a look.
regards
--
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
| From | Date | Subject | |
|---|---|---|---|
| Next Message | John Naylor | 2022-08-18 07:40:36 | Re: build remaining Flex files standalone |
| Previous Message | David Rowley | 2022-08-18 07:27:09 | Re: shadow variables - pg15 edition |