Re: [PATCH] Incremental sort (was: PoC: Partial sort)

From: Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
To: James Coleman <jtc331(at)gmail(dot)com>
Cc: Michael Paquier <michael(at)paquier(dot)xyz>, Rafia Sabih <rafia(dot)pghackers(at)gmail(dot)com>, Peter Geoghegan <pg(at)bowt(dot)ie>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Shaun Thomas <shaun(dot)thomas(at)2ndquadrant(dot)com>, Dmitry Dolgov <9erthalion6(at)gmail(dot)com>, Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL Developers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
Subject: Re: [PATCH] Incremental sort (was: PoC: Partial sort)
Date: 2020-03-13 18:01:50
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(dot)vondra(at)2ndquadrant(dot)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

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