From e16a2db21688b14bfc9394a22d7bff2e2d445c5b Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Fri, 23 May 2025 11:16:04 +0200
Subject: [PATCH] doc PG 18 relnotes: Add incompatibility note about checksums
 now default

---
 doc/src/sgml/release-18.sgml | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/doc/src/sgml/release-18.sgml b/doc/src/sgml/release-18.sgml
index 246e49ce740..d0867b981c0 100644
--- a/doc/src/sgml/release-18.sgml
+++ b/doc/src/sgml/release-18.sgml
@@ -191,6 +191,27 @@ <title>Migration to Version 18</title>
 <para>
 These were previously zero-based.
 </para>
+</listitem>
+
+<!--
+Author: Peter Eisentraut <peter@eisentraut.org>
+2024-10-16 [04bec894a04] initdb: Change default to using data checksums.
+-->
+
+<listitem>
+<para>
+initdb defaults to enabling data checksums
+<ulink url="&commit_baseurl;04bec894a04">&sect;</ulink>
+</para>
+
+<para>
+The previous default behavior (checksums disabled) can be obtained using the
+new option --no-data-checksums.  Note that pg_upgrade will reject upgrading
+between clusters with different checksum settings, so if the old cluster was
+initialized without checksums (the previous default), then the new cluster
+will need to be initialized with --no-data-checksums in order to allow
+pg_upgrade to succeed.
+</para>
 </listitem>
 
    </itemizedlist>
-- 
2.49.0