diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3de489e2f0d..02dab879d9b 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -785,7 +785,9 @@ postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: ser
      <entry>Text of this backend's most recent query. If
       <structfield>state</> is <literal>active</> this field shows the
       currently executing query. In all other states, it shows the last query
-      that was executed.
+      that was executed. By default the query text is truncated at 1024
+      characters; this value can be changed via the parameter
+      <xref linkend="guc-track-activity-query-size">.
      </entry>
     </row>
    </tbody>