diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 828e9084dd..e6c49eebad 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -4078,6 +4078,12 @@ SELECT pg_stat_get_backend_pid(s.backendid) AS pid,
        <command>CLUSTER</command> is currently sorting tuples.
      </entry>
     </row>
+    <row>
+     <entry><literal>writing new heap</literal></entry>
+     <entry>
+       <command>CLUSTER</command> is currently writing the new heap.
+     </entry>
+    </row>
     <row>
      <entry><literal>swapping relation files</literal></entry>
      <entry>