diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml
index 498654876f..c4aaf906c7 100644
--- a/doc/src/sgml/ddl.sgml
+++ b/doc/src/sgml/ddl.sgml
@@ -3970,6 +3970,11 @@ ALTER TABLE measurement ATTACH PARTITION measurement_y2008m02
 </programlisting>
     </para>
 
+    <para>
+     The <command>ATTACH PARTITION</command> command requires taking a
+     <literal>SHARE UPDATE EXCLUSIVE</literal> lock on the partitioned table.
+    </para>
+
     <para>
      Before running the <command>ATTACH PARTITION</command> command, it is
      recommended to create a <literal>CHECK</literal> constraint on the table to
@@ -3978,10 +3983,21 @@ ALTER TABLE measurement ATTACH PARTITION measurement_y2008m02
      which is otherwise needed to validate the implicit
      partition constraint. Without the <literal>CHECK</literal> constraint,
      the table will be scanned to validate the partition constraint while
-     holding both an <literal>ACCESS EXCLUSIVE</literal> lock on that partition
-     and a <literal>SHARE UPDATE EXCLUSIVE</literal> lock on the parent table.
-     It is recommended to drop the now-redundant <literal>CHECK</literal>
-     constraint after <command>ATTACH PARTITION</command> is finished.
+     holding an <literal>ACCESS EXCLUSIVE</literal> lock on that partition
+     and all of its child partitions, if any.  It is recommended to drop the
+     now-redundant <literal>CHECK</literal> constraint after the
+     <command>ATTACH PARTITION </command> is complete.
+    </para>
+
+    <para>
+     Similarly, if the partitioned table has a <literal>DEFAULT</literal>
+     partition, it is recommended to create a <literal>CHECK</literal>
+     constraint which excludes the to-be-attached partition's constraint.  If
+     this is not done then the <literal>DEFAULT</literal> partition will be
+     scanned to verify that it contains no records which should be located in
+     the partition being attached.  This operation will be performed whilst
+     holding an <literal>ACCESS EXCLUSIVE</literal> lock on the <literal>
+     DEFAULT</literal> partition and all of its sub-partitions, if any.
     </para>
 
     <para>
diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c5e5e84e06..281d26fe27 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -965,8 +965,17 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
      <para>
       Attaching a partition acquires a
       <literal>SHARE UPDATE EXCLUSIVE</literal> lock on the parent table,
-      in addition to <literal>ACCESS EXCLUSIVE</literal> locks on the table
-      to be attached and on the default partition (if any).
+      in addition to the <literal>ACCESS EXCLUSIVE</literal> locks on the table
+      being attached and the default partition (if any).
+     </para>
+
+     <para>
+      Further locks must also be held on all sub-partitions if the table being
+      attached is itself a partitioned table.  Likewise if the default
+      partition is itself a partitioned table.  The locking of the
+      sub-partitions can be avoided by adding a <literal>CHECK</literal>
+      constraint as described in
+      <xref linkend="ddl-partitioning-declarative-maintenance"/>.
      </para>
     </listitem>
    </varlistentry>