From 3ca40a2b18a0638994e35160dfc8d392b1aef898 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Thu, 20 Jan 2022 16:54:58 +0900
Subject: [PATCH] doc: Mention the level of locks taken on objects in COMMENT

This information was nowhere to be found.  This adds one note on the
page of COMMENT, and one note in the section dedicated to explicit
locking, both telling that a SHARE UPDATE EXCLUSIVE lock is taken on the
object commented.

Author: Nikolai Berkoff
Reviewed-by: Laurenz Albe
Discussion: https://postgr.es/m/_0HDHIGcCdCsUyXn22QwI2FEuNR6Fs71rtgGX6hfyBlUh5rrnE2qMmvIFu9EY4Pijr2gUmJEAXCjuNU2Oxku9TryLp9CdHllpsCfN3gD0-Y=@pm.me
Backpatch-through: 10
---
 doc/src/sgml/mvcc.sgml        | 9 +++++----
 doc/src/sgml/ref/comment.sgml | 5 +++++
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/doc/src/sgml/mvcc.sgml b/doc/src/sgml/mvcc.sgml
index 5e3b7477e38..23c5a2d1cb4 100644
--- a/doc/src/sgml/mvcc.sgml
+++ b/doc/src/sgml/mvcc.sgml
@@ -950,11 +950,12 @@ ERROR:  could not serialize access due to read/write dependencies among transact
         <para>
          Acquired by <command>VACUUM</command> (without <option>FULL</option>),
          <command>ANALYZE</command>, <command>CREATE INDEX CONCURRENTLY</command>,
+         <command>CREATE STATISTICS</command>, <command>COMMENT ON</command>,
          <command>REINDEX CONCURRENTLY</command>,
-         <command>CREATE STATISTICS</command>, and certain <command>ALTER
-         INDEX</command> and <command>ALTER TABLE</command> variants (for full
-         details see <xref linkend="sql-alterindex"/> and <xref
-         linkend="sql-altertable"/>).
+         and certain <command>ALTER INDEX</command> and
+         <command>ALTER TABLE</command> variants
+         (for full details see <xref linkend="sql-alterindex"/> and
+         <xref linkend="sql-altertable"/>).
         </para>
        </listitem>
       </varlistentry>
diff --git a/doc/src/sgml/ref/comment.sgml b/doc/src/sgml/ref/comment.sgml
index fd7492a2556..138cf718ce1 100644
--- a/doc/src/sgml/ref/comment.sgml
+++ b/doc/src/sgml/ref/comment.sgml
@@ -90,6 +90,11 @@ COMMENT ON
    Comments are automatically dropped when their object is dropped.
   </para>
 
+  <para>
+   A <literal>SHARE UPDATE EXCLUSIVE</literal> lock is acquired on the
+   object to be commented.
+  </para>
+
   <para>
    For most kinds of object, only the object's owner can set the comment.
    Roles don't have owners, so the rule for <literal>COMMENT ON ROLE</literal> is