Re: support for MERGE

From: Justin Pryzby <pryzby(at)telsasoft(dot)com>
To: Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>
Cc: Peter Eisentraut <peter(dot)eisentraut(at)enterprisedb(dot)com>, Amit Langote <amitlangote09(at)gmail(dot)com>, Japin Li <japinli(at)hotmail(dot)com>, Zhihong Yu <zyu(at)yugabyte(dot)com>, Simon Riggs <simon(dot)riggs(at)enterprisedb(dot)com>, pgsql-hackers(at)lists(dot)postgresql(dot)org, Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com>, Daniel Westermann <dwe(at)dbi-services(dot)com>, Erik Rijkers <er(at)xs4all(dot)nl>, Jaime Casanova <jcasanov(at)systemguards(dot)com(dot)ec>, Andres Freund <andres(at)anarazel(dot)de>
Subject: Re: support for MERGE
Date: 2022-05-18 16:57:15
Message-ID: 20220518165715.GJ19626@telsasoft.com
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On Wed, May 18, 2022 at 06:42:38PM +0200, Alvaro Herrera wrote:
> On 2022-May-11, Justin Pryzby wrote:
>
> > I suggest to reference the mvcc docs from the merge docs, or to make the merge
> > docs themselves include the referenced information.
> >
> > diff --git a/doc/src/sgml/ref/merge.sgml b/doc/src/sgml/ref/merge.sgml
> > index f68aa09736c..99dd5814f36 100644
> > --- a/doc/src/sgml/ref/merge.sgml
> > +++ b/doc/src/sgml/ref/merge.sgml
> > @@ -544,6 +544,7 @@ MERGE <replaceable class="parameter">total_count</replaceable>
> > <command>UPDATE</command> if a concurrent <command>INSERT</command>
> > occurs. There are a variety of differences and restrictions between
> > the two statement types and they are not interchangeable.
> > + See <xref linkend="mvcc"/> for more information.
>
> Reading the paragraph, I think it may be better to do it the other way
> around: first mention that concurrency is described in the MVCC page,
> then explain that INSERT ON CONFLICT also exists. What do you think of
> the attached?

Hmm, it seems odd to put "see also" first.

My original complaint is that 1) merge.sgml doesn't include the detailed
information; but 3) mentions it vaguely without linking to it: "There are a
variety of differences and restrictions between the two statement types and
they are not interchangeable."

I prefer my original, but the most important thing is to include the link at
*somewhere*.

--
Justin

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