Horton

Re: support for MERGE

Justin Pryzby <pryzby@telsasoft.com>

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From: Justin Pryzby <pryzby@telsasoft.com>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Peter Eisentraut <peter.eisentraut@enterprisedb.com>, Amit Langote <amitlangote09@gmail.com>, Japin Li <japinli@hotmail.com>, Zhihong Yu <zyu@yugabyte.com>, Simon Riggs <simon.riggs@enterprisedb.com>, 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>
Date: 2022-05-18T16:57:15Z
Lists: pgsql-hackers 
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

Commits

  1. Doc fixes for MERGE statement

  2. MERGE docs adjustments

  3. Link to MVCC docs in MERGE docs

  4. Fix EXPLAIN MERGE output when no tuples are processed

  5. Make EXPLAIN MERGE output format more compact

  6. Add support for MERGE SQL command

  7. Split ExecUpdate and ExecDelete into reusable pieces

  8. Add API of sorts for transition table handling in trigger.c

  9. Represent Lists as expansible arrays, not chains of cons-cells.