From 534dbe09fa0f787b2b60d7cf5edd8d87dff378a4 Mon Sep 17 00:00:00 2001
From: Hayato Kuroda <kuroda.hayato@fujitsu.com>
Date: Tue, 9 Jul 2024 08:01:43 +0000
Subject: [PATCH v20 3/3] Notify users to roll back prepared transactions

---
 doc/src/sgml/ref/alter_subscription.sgml | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/doc/src/sgml/ref/alter_subscription.sgml b/doc/src/sgml/ref/alter_subscription.sgml
index df44415661..26f423a424 100644
--- a/doc/src/sgml/ref/alter_subscription.sgml
+++ b/doc/src/sgml/ref/alter_subscription.sgml
@@ -233,8 +233,6 @@ ALTER SUBSCRIPTION <replaceable class="parameter">name</replaceable> RENAME TO <
       <link linkend="sql-createsubscription-params-with-failover"><literal>failover</literal></link>, and
       <link linkend="sql-createsubscription-params-with-two-phase"><literal>two_phase</literal></link>.
       Only a superuser can set <literal>password_required = false</literal>.
-      The <literal>two_phase</literal> parameter can only be altered when the
-      subscription is disabled.
      </para>
 
      <para>
@@ -256,6 +254,25 @@ ALTER SUBSCRIPTION <replaceable class="parameter">name</replaceable> RENAME TO <
       <link linkend="sql-createsubscription-params-with-failover"><literal>failover</literal></link>
       option is enabled.
      </para>
+
+     <para>
+      The <link linkend="sql-createsubscription-params-with-failover"><literal>failover</literal></link>
+      and <link linkend="sql-createsubscription-params-with-two-phase"><literal>two_phase</literal></link>
+      parameters can only be altered when the subscription is disabled.
+     </para>
+
+     <para>
+      When altering <link linkend="sql-createsubscription-params-with-two-phase"><literal>two_phase</literal></link>
+      from <literal>true</literal> to <literal>false</literal>,
+      the backend process checks for any incomplete prepared transactions done
+      by the logical replication worker (from when <literal>two_phase</literal>
+      parameter was still <literal>true</literal>) and, if any are found, an
+      error is reported. If this happens, you can resolve prepared transactions
+      on the publisher node or manually roll back them on the subscriber, then
+      try again. After the altering from <literal>true</literal> to
+      <literal>false</literal>, the publisher will replicate transactions again
+      when they are committed.
+     </para>
     </listitem>
    </varlistentry>
 
-- 
2.43.0