From: | Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com> |
---|---|
To: | David Rowley <dgrowleyml(at)gmail(dot)com> |
Cc: | Andres Freund <andres(at)anarazel(dot)de>, Tomas Vondra <tv(at)fuzzy(dot)cz>, PostgreSQL Developers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
Subject: | Re: Use generation context to speed up tuplesorts |
Date: | 2021-08-08 12:28:10 |
Message-ID: | 330e3918-df5c-1ef5-01bb-d3387d12e86d@enterprisedb.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
On 8/8/21 9:02 AM, David Rowley wrote:
> On Sat, 7 Aug 2021 at 12:10, Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com> wrote:
>>
>> On 8/6/21 3:07 PM, David Rowley wrote:
>>> All of the tests show that the patches to improve the allocation
>>> efficiency of generation.c don't help to improve the results of the
>>> test cases. I wondered if it's maybe worth trying to see what happens
>>> if instead of doubling the allocations each time, quadruple them
>>> instead. I didn't try this.
>>>
>>
>> I doubt quadrupling the allocations won't help very much, but I suspect
>> the problem might be in the 0004 patch - at least that's what shows
>> regression in my results. Could you try with just 0001-0003 applied?
>
> But 0004 only changes the logic which controls the threshold of when
> we allocate an oversized chunk. It looks like the threshold is 512KB
> with the 0004 patch. My test is only doing a maximum allocation of
> 296 bytes so will never allocate an oversized chunk.
>
> Can you explain why you think 0004 would cause performance regressions?
>
It's based solely on results of my benchmarks, where this patch seems to
cause performance regression. I agree it's a bit bizzare, considering
what the patch does.
regards
--
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
From | Date | Subject | |
---|---|---|---|
Next Message | Tomas Vondra | 2021-08-08 12:38:00 | Re: Use generation context to speed up tuplesorts |
Previous Message | David Rowley | 2021-08-08 11:56:41 | Strange code in EXPLAIN for queryid |