From a65eb067ff48d8ea1f4b12e437b0a00d0dac54a2 Mon Sep 17 00:00:00 2001
From: Nathan Bossart <nathan@postgresql.org>
Date: Fri, 27 Jun 2025 14:33:30 -0500
Subject: [PATCH v6 1/1] Document pg_get_multixact_members().
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Oversight in commit 0ac5ad5134.

Author: Sami Imseih <samimseih@gmail.com>
Co-authored-by: Álvaro Herrera <alvherre@kurilemu.de>
Reviewed-by: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Discussion: https://postgr.es/m/20150619215231.GT133018%40postgresql.org
Discussion: https://postgr.es/m/CAA5RZ0sjQDDwJfMRb%3DZ13nDLuRpF13ME2L_BdGxi0op8RKjmDg%40mail.gmail.com
Backpatch-through: 13
---
 doc/src/sgml/func.sgml        | 25 +++++++++++++++++++++++++
 doc/src/sgml/maintenance.sgml |  5 ++++-
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 224d4fe5a9f..d2968a2d175 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -27687,6 +27687,31 @@ acl      | {postgres=arwdDxtm/postgres,foo=r/postgres}
         details.
        </para></entry>
       </row>
+
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_get_multixact_members</primary>
+        </indexterm>
+        <function>pg_get_multixact_members</function> ( <parameter>multixid</parameter> <type>xid</type> )
+        <returnvalue>setof record</returnvalue>
+        ( <parameter>xid</parameter> <type>xid</type>,
+        <parameter>mode</parameter> <type>text</type> )
+       </para>
+       <para>
+        Returns the transaction ID and lock mode for each member of the
+        specified multixact ID.  The lock modes <literal>forupd</literal>,
+        <literal>fornokeyupd</literal>, <literal>sh</literal>, and
+        <literal>keysh</literal> correspond to the row-level locks
+        <literal>FOR UPDATE</literal>, <literal>FOR NO KEY UPDATE</literal>,
+        <literal>FOR SHARE</literal>, and <literal>FOR KEY SHARE</literal>,
+        respectively, as described in <xref linkend="locking-rows"/>.  Two
+        additional modes are specific to multixacts:
+        <literal>nokeyupd</literal>, used by updates that do not modify key
+        columns, and <literal>upd</literal>, used by updates or deletes that
+        modify key columns.
+       </para></entry>
+      </row>
      </tbody>
     </tgroup>
    </table>
diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml
index 600e4b3f2f3..e7a9f58c015 100644
--- a/doc/src/sgml/maintenance.sgml
+++ b/doc/src/sgml/maintenance.sgml
@@ -779,7 +779,10 @@ HINT:  Execute a database-wide VACUUM in that database.
      careful aging management, storage cleanup, and wraparound handling.
      There is a separate storage area which holds the list of members in
      each multixact, which also uses a 32-bit counter and which must also
-     be managed.
+     be managed.  The system function
+     <function>pg_get_multixact_members()</function> described in
+     <xref linkend="functions-pg-snapshot"/> can be used to examine the
+     transaction IDs associated with a multixact ID.
     </para>
 
     <para>
-- 
2.39.5 (Apple Git-154)