diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml
index cae307470c8..f99052fa5c2 100644
--- a/doc/src/sgml/ddl.sgml
+++ b/doc/src/sgml/ddl.sgml
@@ -4029,7 +4029,7 @@ ALTER TABLE measurement ATTACH PARTITION measurement_y2008m02
 <programlisting>
 CREATE INDEX measurement_usls_idx ON ONLY measurement (unitsales);
 
-CREATE INDEX measurement_usls_200602_idx
+CREATE INDEX CONCURRENTLY measurement_usls_200602_idx
     ON measurement_y2006m02 (unitsales);
 ALTER INDEX measurement_usls_idx
     ATTACH PARTITION measurement_usls_200602_idx;