From 44ab2dac12a752022eb4fe3dba7beddbc3433a0e Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Thu, 20 Jan 2022 16:55:08 +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        | 2 +-
 doc/src/sgml/ref/comment.sgml | 5 +++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/doc/src/sgml/mvcc.sgml b/doc/src/sgml/mvcc.sgml
index 7e20a8a796..40159b8dcd 100644
--- a/doc/src/sgml/mvcc.sgml
+++ b/doc/src/sgml/mvcc.sgml
@@ -950,7 +950,7 @@ 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> and
+         <command>CREATE STATISTICS</command>, <command>COMMENT ON</command> and
          <command>ALTER TABLE VALIDATE</command> and other
          <command>ALTER TABLE</command> variants (for full details see
          <xref linkend="sql-altertable"/>).
diff --git a/doc/src/sgml/ref/comment.sgml b/doc/src/sgml/ref/comment.sgml
index fd7492a255..138cf718ce 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