From d800b036d2e7c7dddf3114f1f02ca16824c13769 Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Sat, 29 May 2010 19:06:16 +0000
Subject: [PATCH] Document that NOT NULL domain constraints are not always
honored.
---
doc/src/sgml/ref/create_domain.sgml | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/doc/src/sgml/ref/create_domain.sgml b/doc/src/sgml/ref/create_domain.sgml
index 637326b58bb..eb3bb3d9823 100644
--- a/doc/src/sgml/ref/create_domain.sgml
+++ b/doc/src/sgml/ref/create_domain.sgml
@@ -1,5 +1,5 @@
<!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/create_domain.sgml,v 1.34 2010/04/03 07:22:58 petere Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/create_domain.sgml,v 1.35 2010/05/29 19:06:16 momjian Exp $
PostgreSQL documentation
-->
@@ -121,7 +121,12 @@ CREATE DOMAIN <replaceable class="parameter">name</replaceable> [ AS ] <replacea
<term><literal>NOT NULL</></term>
<listitem>
<para>
- Values of this domain are not allowed to be null.
+ Values of this domain are normally prevented from being null.
+ However, it is still possible for a domain with this constraint
+ to take a null value if it is assigned a matching domain type
+ that has become null, e.g. via a LEFT OUTER JOIN, or
+ <command>INSERT INTO tab (domcol) VALUES ((SELECT domcol FROM
+ tab WHERE false))</command>.
</para>
</listitem>
</varlistentry>
--
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