2 files changed, 25 insertions, 1 deletions

diff --git a/doc/src/sgml/backup.sgml b/doc/src/sgml/backup.sgml
index b3468eea3cb..91da3c26ba0 100644
--- a/doc/src/sgml/backup.sgml
+++ b/doc/src/sgml/backup.sgml
@@ -892,7 +892,11 @@ test ! -f /mnt/server/archivedir/00000001000000A900000065 && cp pg_wal/0
     only the incremental backup itself but also all earlier backups that
     are required to supply the blocks omitted from the incremental backup.
     See <xref linkend="app-pgcombinebackup"/> for further information about
-    this requirement.
+    this requirement. Note that there are restrictions on the use of
+    <literal>pg_combinebackup</literal> when the checksum status of the
+    cluster has been changed; see
+    <link linkend="app-pgcombinebackup-limitations">pg_combinebackup
+    limitations</link>.
    </para>
 
    <para>
diff --git a/doc/src/sgml/ref/pg_combinebackup.sgml b/doc/src/sgml/ref/pg_combinebackup.sgml
index 96df3d81f15..d1f70ba2358 100644
--- a/doc/src/sgml/ref/pg_combinebackup.sgml
+++ b/doc/src/sgml/ref/pg_combinebackup.sgml
@@ -261,6 +261,26 @@ PostgreSQL documentation
 
  </refsect1>
 
+ <refsect1 id="app-pgcombinebackup-limitations">
+  <title>Limitations</title>
+
+  <para>
+   <literal>pg_combinebackup</literal> does not recompute page checksums when
+   writing the output directory. Therefore, if any of the backups used for
+   reconstruction were taken with checksums disabled, but the final backup was
+   taken with checksums enabled, the resulting directory may contain pages
+   with invalid checksums.
+  </para>
+
+  <para>
+   To avoid this problem, taking a new full backup after changing the checksum
+   state of the cluster using <xref linkend="app-pgchecksums "/> is
+   recommended. Otherwise, you can disable and then optionally reenable
+   checksums on the directory produced by <literal>pg_combinebackup</literal>
+   in order to correct the problem.
+  </para>
+ </refsect1>
+
  <refsect1>
   <title>Environment</title>