Date: Thu, 17 Mar 2022 19:36:48 +0100
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Justin Pryzby <pryzby@telsasoft.com>,
	Amit Langote <amitlangote09@gmail.com>,
	Japin Li <japinli@hotmail.com>
Cc: Zhihong Yu <zyu@yugabyte.com>,
	Simon Riggs <simon.riggs@enterprisedb.com>,
	Pg Hackers <pgsql-hackers@lists.postgresql.org>,
	Tomas Vondra <tomas.vondra@enterprisedb.com>,
	Daniel Westermann <dwe@dbi-services.com>,
	Erik Rijkers <er@xs4all.nl>,
	Jaime Casanova <jcasanov@systemguards.com.ec>,
	Andres Freund <andres@anarazel.de>
Subject: Re: support for MERGE
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On 2022-Mar-17, Alvaro Herrera wrote:

> I'll see what to do about Instrumentation->nfiltered{1,2,3} that was
> complained about by Andres upthread.  Maybe some additional macros will
> help.

This turns out not to be as simple as I expected, mostly because we want
to keep Instrumentation as a node-agnostic struct.  Things are already a
bit wonky with nfiltered/nfiltered2, and the addition of nfiltered3
makes things a lot uglier, and my impulse of using a union to separate
what is used for scans/joins vs. what is used for MERGE results in an
even more node-specific definition rather than the other way around.

Looking at the history I came across this older thread where this was
discussed
https://postgr.es/m/20180409215851.idwc75ct2bzi6tea@alvherre.pgsql
particularly this message from Robert,
https://www.postgresql.org/message-id/CA%2BTgmoaE3R6%3DV0G6zbht2L_LE%2BTsuYuSTPJXjLW%2B9_tpMGubZQ%40mail.gmail.com

I'll keep looking at this in the coming days, see if I can come up with
something sensible.

-- 
Álvaro Herrera           39°49'30"S 73°17'W  —  https://www.EnterpriseDB.com/
Y una voz del caos me habló y me dijo
"Sonríe y sé feliz, podría ser peor".
Y sonreí. Y fui feliz.
Y fue peor.