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From: Kefan Yang <starordust@gmail.com>
To: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: Andrey Borodin <x4mmm@yandex-team.ru>
Cc: Peter Geoghegan <pg@bowt.ie>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: RE: GSOC 2018 Project - A New Sorting Routine
Date: Wed, 18 Jul 2018 14:13:38 -0700
Message-ID: <5b4fad82.1c69fb81.7a6f6.d32b@mx.google.com> (raw)
In-Reply-To: <78b9c822-e127-5250-a01c-4c51a50c82bd@2ndquadrant.com>
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	<78b9c822-e127-5250-a01c-4c51a50c82bd@2ndquadrant.com>

Hey Tomas!

I am trying to reproduce the results on my machine. Could you please share the script to generate .ods files?

Regards,
Kefan

From: Tomas Vondra
Sent: July 18, 2018 2:05 AM
To: Andrey Borodin
Cc: Peter Geoghegan; Kefan Yang; PostgreSQL Hackers
Subject: Re: GSOC 2018 Project - A New Sorting Routine



On 07/18/2018 07:06 AM, Andrey Borodin wrote:
> Hi, Tomas!
> 
>> 15 июля 2018 г., в 1:20, Tomas Vondra <tomas.vondra@2ndquadrant.com 
>> <mailto:tomas.vondra@2ndquadrant.com>> написал(а):
>>
>> So I doubt it's this, but I've tweaked the scripts to also set this GUC
>> and restarted the tests on both machines. Let's see what that does.
> 
> Do you observe any different results?
> 

It did change the CREATE INDEX results, depending on the scale. The full 
data is available at [1] and [2], attached is a spreadsheet summary from 
the Xeon box.

For the largest scale (1M rows) the regressions for CREATE INDEX queries 
mostly disappeared. For 10k rows it still affects CREATE INDEX with a 
text column, and the 100k case behaves just like before (so significant 
regressions for CREATE INDEX).

I don't have time to investigate this further at the moment, but I'm 
still of the opinion that there's little to gain by replacing our 
current sort algorithm with this.


[1] https://bitbucket.org/tvondra/sort-intro-sort-xeon/src/master/
[2] https://bitbucket.org/tvondra/sort-intro-sort-i5/src/master/

regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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