Message-ID: <2d5d480b-d9e5-9d8f-dbca-ad6ec22a1b75@enterprisedb.com>
Date: Mon, 5 Sep 2022 00:14:48 +0200
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.9.0
Subject: Re: POC: GROUP BY optimization
Content-Language: en-US
To: "Jonathan S. Katz" <jkatz@postgresql.org>,
 David Rowley <dgrowleyml@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>, Zhihong Yu <zyu@yugabyte.com>,
 "Andrey V. Lepikhov" <a.lepikhov@postgrespro.ru>,
 Teodor Sigaev <teodor@sigaev.ru>, Tomas Vondra
 <tomas.vondra@2ndquadrant.com>,
 PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>
References: <721b3ff9-f214-f5d4-86c7-bae515bbec18@enterprisedb.com>
 <9af89543-3d17-4c98-59de-1daa5bceeb06@enterprisedb.com>
 <9408e450-60c6-6fbc-d5c4-467bb0abfe67@postgrespro.ru>
 <44472925-f6c6-e8de-6f72-0451458532c4@enterprisedb.com>
 <CALNJ-vQp3WNV-kKuGsjSOhjRfdECA1Dbxa-vjAgOmQ4f4Qaw-Q@mail.gmail.com>
 <7a80a207-5e8e-b80c-476c-2d290b0526e9@enterprisedb.com>
 <65941e87-86c1-c09c-8ad5-8e102aebe8ee@enterprisedb.com>
 <CAApHDvpVFgWzXdtUQkjyOPhNrNvumRi_=ftgS79KeAZ92tnHKQ@mail.gmail.com>
 <aada8f97-924e-5661-aead-257aa346899c@enterprisedb.com>
 <Yuj6mQomSuhoti9D@paquier.xyz>
 <CAApHDvruRZ0cVw0rsjoGSgoQF5fn2UoJ2cWLgZSVza0M1Y1KPg@mail.gmail.com>
 <683635b8-381b-5b08-6069-d6a45de19a12@enterprisedb.com>
 <CAApHDvr+95wJcABsqSXWcBa+yyUmJ2bq_mnZs9dUnaOi3XRVMg@mail.gmail.com>
 <a16ac766-f898-3299-28fd-5aabfa6f308d@enterprisedb.com>
 <77b83b6d-bdb4-614d-4e7d-235ee72e2599@postgresql.org>
 <217ab546-4c78-9364-9282-a6dcefa066ea@enterprisedb.com>
 <9e564f8b-2c4b-6c6f-9334-e76e69af8f84@postgresql.org>
From: Tomas Vondra <tomas.vondra@enterprisedb.com>
In-Reply-To: <9e564f8b-2c4b-6c6f-9334-e76e69af8f84@postgresql.org>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Archived-At: 
 <https://www.postgresql.org/message-id/2d5d480b-d9e5-9d8f-dbca-ad6ec22a1b75%40enterprisedb.com>
Precedence: bulk

On 9/1/22 16:05, Jonathan S. Katz wrote:
> On 9/1/22 9:06 AM, Tomas Vondra wrote:
>>
>>
>> On 8/30/22 15:15, Jonathan S. Katz wrote:
>>> On 8/18/22 3:29 AM, Tomas Vondra wrote:
>>>>
>>>>
>>>> On 8/18/22 03:32, David Rowley wrote:
>>>
>>>>> 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.
>>>
>>> With RMT hat on, just a friendly reminder that this is still on the open
>>> items list[1] -- we have the Beta 4 release next week and it would be
>>> great if we can get this resolved prior to it.
>>>
>>
>> I know. I'll fix this by tweaking one of the cost gucs, mentioned by
>> David.
> 
> Great -- thanks for the update!
> 

I've pushed the fix to 15+master. In the end I just used David's patches
that set parallel_setup_cost to 0.


regards

-- 
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company