From 2bf23cd8018c7e2cbff4f00be4aba1e806750998 Mon Sep 17 00:00:00 2001
From: Matthias van de Meent <boekewurm@gmail.com>
Date: Thu, 15 Apr 2021 20:43:00 +0200
Subject: [PATCH v1] ATTACH PARTITION locking documentation for DEFAULT
 partitions.

---
 doc/src/sgml/ddl.sgml | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml
index 30e4170963..f001f0b8a3 100644
--- a/doc/src/sgml/ddl.sgml
+++ b/doc/src/sgml/ddl.sgml
@@ -3934,6 +3934,9 @@ ALTER TABLE measurement_y2008m02 ADD CONSTRAINT y2008m02
 \copy measurement_y2008m02 from 'measurement_y2008m02'
 -- possibly some other data preparation work
 
+ALTER TABLE measurement_default ADD CONSTRAINT excl_y2008m02
+   CHECK ( (logdate &gt;= DATE '2008-02-01' AND logdate &lt; DATE '2008-03-01') IS FALSE );
+
 ALTER TABLE measurement ATTACH PARTITION measurement_y2008m02
     FOR VALUES FROM ('2008-02-01') TO ('2008-03-01' );
 </programlisting>
@@ -3953,6 +3956,21 @@ ALTER TABLE measurement ATTACH PARTITION measurement_y2008m02
      constraint after <command>ATTACH PARTITION</command> is finished.
     </para>
 
+    <para>
+     Similarly, if you have a default partition on the parent table, it is
+     recommended to create a <literal>CHECK</literal> constraint that excludes
+     the to be attached partition constraint. Here, too, without the
+     <literal>CHECK</literal> constraint, this table will be scanned to
+     validate that the updated default partition constraints while holding
+     an <literal>ACCESS EXCLUSIVE</literal> lock on the default partition.
+    </para>
+
+    <para>
+     Note that the locks on both the table that is being attached and the 
+     default partition are both recursive to all their child partitions, if 
+     these tables are partitioned tables themselves.
+    </para>
+
     <para>
      As explained above, it is possible to create indexes on partitioned tables
      so that they are applied automatically to the entire hierarchy.
-- 
2.20.1