diff --git i/doc/src/sgml/mvcc.sgml w/doc/src/sgml/mvcc.sgml
index cfdcb742..06ed5985 100644
--- i/doc/src/sgml/mvcc.sgml
+++ w/doc/src/sgml/mvcc.sgml
@@ -951,7 +951,7 @@ ERROR:  could not serialize access due to read/write dependencies among transact
          Acquired by <command>VACUUM</command> (without <option>FULL</option>),
          <command>ANALYZE</command>, <command>CREATE INDEX CONCURRENTLY</command>,
          <command>REINDEX CONCURRENTLY</command>,
-         <command>CREATE STATISTICS</command>, and certain <link linkend="sql-alterindex"><command>ALTER
+         <command>CREATE STATISTICS</command>, <command>COMMENT ON</command>, and certain <link linkend="sql-alterindex"><command>ALTER
          INDEX</command></link> and <link linkend="sql-altertable"><command>ALTER TABLE</command></link> variants (for full
          details see the documentation of these commands).
         </para>
diff --git i/doc/src/sgml/ref/comment.sgml w/doc/src/sgml/ref/comment.sgml
index e07fc47f..04361e73 100644
--- i/doc/src/sgml/ref/comment.sgml
+++ w/doc/src/sgml/ref/comment.sgml
@@ -88,6 +88,7 @@ COMMENT ON
    issue a new <command>COMMENT</command> command for the same object.  To remove a
    comment, write <literal>NULL</literal> in place of the text string.
    Comments are automatically dropped when their object is dropped.
+   A SHARE UPDATE EXCLUSIVE lock is acquired on the object.
   </para>
 
   <para>