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?
--
Álvaro Herrera Breisgau, Deutschland — https://www.EnterpriseDB.com/
>From 5bad2c5a4bcd2bf04751f980f947c1050aeafd03 Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvhe...@alvh.no-ip.org>
Date: Wed, 18 May 2022 18:41:04 +0200
Subject: [PATCH v2] Link to MVCC docs in MERGE docs.
---
doc/src/sgml/mvcc.sgml | 2 +-
doc/src/sgml/ref/merge.sgml | 2 ++
2 files changed, 3 insertions(+), 1 deletion(-)
diff --git a/doc/src/sgml/mvcc.sgml b/doc/src/sgml/mvcc.sgml
index 341fea524a..4446e1c484 100644
--- a/doc/src/sgml/mvcc.sgml
+++ b/doc/src/sgml/mvcc.sgml
@@ -425,7 +425,7 @@ COMMIT;
<para>
<command>MERGE</command> allows the user to specify various
combinations of <command>INSERT</command>, <command>UPDATE</command>
- or <command>DELETE</command> subcommands. A <command>MERGE</command>
+ and <command>DELETE</command> subcommands. A <command>MERGE</command>
command with both <command>INSERT</command> and <command>UPDATE</command>
subcommands looks similar to <command>INSERT</command> with an
<literal>ON CONFLICT DO UPDATE</literal> clause but does not
diff --git a/doc/src/sgml/ref/merge.sgml b/doc/src/sgml/ref/merge.sgml
index f68aa09736..6b94c863b5 100644
--- a/doc/src/sgml/ref/merge.sgml
+++ b/doc/src/sgml/ref/merge.sgml
@@ -539,6 +539,8 @@ MERGE <replaceable class="parameter">total_count</replaceable>
</para>
<para>
+ See <xref linkend="mvcc"/> for more details on the behavior of
+ <command>MERGE</command> under concurrency.
You may also wish to consider using <command>INSERT ... ON CONFLICT</command>
as an alternative statement which offers the ability to run an
<command>UPDATE</command> if a concurrent <command>INSERT</command>
--
2.30.2
