From 0cc31cc32da0ff6b3569eb73249eb1549b8731d1 Mon Sep 17 00:00:00 2001
From: Etsuro Fujita <efujita@postgresql.org>
Date: Fri, 8 Nov 2019 17:00:31 +0900
Subject: postgres_fdw: Fix error message for PREPARE TRANSACTION.

Currently, postgres_fdw does not support preparing a remote transaction
for two-phase commit even in the case where the remote transaction is
read-only, but the old error message appeared to imply that that was not
supported only if the remote transaction modified remote tables.  Change
the message so as to include the case where the remote transaction is
read-only.

Also fix a comment above the message.

Also add a note about the lack of supporting PREPARE TRANSACTION to the
postgres_fdw documentation.

Reported-by: Gilles Darold
Author: Gilles Darold and Etsuro Fujita
Reviewed-by: Michael Paquier and Kyotaro Horiguchi
Backpatch-through: 9.4
Discussion: https://postgr.es/m/08600ed3-3084-be70-65ba-279ab19618a5%40darold.net
---
 doc/src/sgml/postgres-fdw.sgml | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'doc/src')

diff --git a/doc/src/sgml/postgres-fdw.sgml b/doc/src/sgml/postgres-fdw.sgml
index 634a7141ef1..ed369cb54b8 100644
--- a/doc/src/sgml/postgres-fdw.sgml
+++ b/doc/src/sgml/postgres-fdw.sgml
@@ -483,6 +483,12 @@
    COMMITTED</literal> local transaction.  A future
    <productname>PostgreSQL</productname> release might modify these rules.
   </para>
+
+  <para>
+   Note that it is currently not supported by
+   <filename>postgres_fdw</filename> to prepare the remote transaction for
+   two-phase commit.
+  </para>
  </sect2>
 
  <sect2>
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