Date: Fri, 13 Mar 2020 19:01:50 +0100
From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
To: James Coleman <jtc331@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>,
	Rafia Sabih <rafia.pghackers@gmail.com>,
	Peter Geoghegan <pg@bowt.ie>, Simon Riggs <simon@2ndquadrant.com>,
	Shaun Thomas <shaun.thomas@2ndquadrant.com>,
	Dmitry Dolgov <9erthalion6@gmail.com>,
	Alexander Korotkov <a.korotkov@postgrespro.ru>,
	Tom Lane <tgl@sss.pgh.pa.us>,
	PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>,
	Alvaro Herrera <alvherre@2ndquadrant.com>
Subject: Re: [PATCH] Incremental sort (was: PoC: Partial sort)
Message-ID: <20200313180150.fud6yy3pji25hid7@development>
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On Fri, Mar 13, 2020 at 01:16:44PM -0400, James Coleman wrote:
>On Tue, Mar 10, 2020 at 10:44 PM Tomas Vondra
><tomas.vondra@2ndquadrant.com> wrote:
>...
>> Now, a couple comments about parts 0001 - 0003 of the patch ...
>>
>> 1) I see a bunch of failures in the regression test, due to minor
>> differences in the explain output. All the differences are about minor
>> changes in memory usage, like this:
>>
>> -               "Sort Space Used": 30,                             +
>> +               "Sort Space Used": 29,                             +
>>
>> I'm not sure if it happens on my machine only, but maybe the test is not
>> entirely stable.
>
>make check passes on multiple machines for me; what arch/distro are you using?
>

Nothing exotic - Fedora on x64. My guess is that things like enabling
asserts will make a difference too, because then we track additional
stuff for allocated chunks etc. So I agree with Tom trying to keep this
stable is a lost cause, essentially.


regards

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