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

From: Peter Geoghegan <pg(at)bowt(dot)ie>
To: James Coleman <jtc331(at)gmail(dot)com>
Cc: Justin Pryzby <pryzby(at)telsasoft(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz>, Rafia Sabih <rafia(dot)pghackers(at)gmail(dot)com>, 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>, PostgreSQL Developers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, Andreas Karlsson <andreas(at)proxel(dot)se>
Subject: Re: [PATCH] Incremental sort (was: PoC: Partial sort)
Date: 2020-07-14 06:55:17
Message-ID: CAH2-Wz=kbMtVnkwjR2BgypCZ0xZ=QL=Te8_7rCoW1mEymATeTg@mail.gmail.com
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On Thu, Jul 2, 2020 at 8:47 AM James Coleman <jtc331(at)gmail(dot)com> wrote:
> It seems like the consensus over at another discussion on this topic
> [1] is that we ought to go ahead and print the zeros [for machine
> readable output formats], even though that creates some interesting
> scenarios like the fact that disk sorts will print 0 for memory even
> though that's not true.

What about having it print -1 for memory in this case instead? That's
still not ideal, but machine readable EXPLAIN output ought to
consistently show the same information per node, even when the answer
is in some sense indeterminate. That seems to be the standard that
we've settled on.

It might be worth teaching the JSON format to show a JSON null or
something instead. Not sure about that, though.

--
Peter Geoghegan

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