From 7ba72f024223cbe1a8e1da1220b8f8efb8e8f215 Mon Sep 17 00:00:00 2001
From: amit <amitlangote09@gmail.com>
Date: Mon, 3 Apr 2017 16:45:15 +0900
Subject: [PATCH] Clarify that partition constraint is not enforced on foreign
 tables

---
 doc/src/sgml/ddl.sgml                      | 15 ++++++++++++---
 doc/src/sgml/ref/create_foreign_table.sgml | 17 +++++++++++------
 2 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml
index b05a9c2150..e7a10e15d3 100644
--- a/doc/src/sgml/ddl.sgml
+++ b/doc/src/sgml/ddl.sgml
@@ -2988,9 +2988,10 @@ VALUES ('Albany', NULL, NULL, 'NY');
    <para>
     Partitions can also be foreign tables
     (see <xref linkend="sql-createforeigntable">),
-    although these have some limitations that normal tables do not.  For
-    example, data inserted into the partitioned table is not routed to
-    foreign table partitions.
+    although they have some limitations that normal tables do not.  For
+    example, routing the data inserted into the partitioned table to foreign
+    table partitions is not supported, nor are the partition constraints
+    enforced when the data is directly inserted into them.
    </para>
 
    <sect3 id="ddl-partitioning-declarative-example">
@@ -3297,6 +3298,14 @@ ALTER TABLE measurement ATTACH PARTITION measurement_y2008m02
        not the partitioned table.
       </para>
      </listitem>
+
+     <listitem>
+      <para>
+       Routing tuples to partitions that are foreign tables is not supported.
+       So, if an inserted tuple routes to one of the foreign partitions, an
+       error will occur.
+      </para>
+     </listitem>
     </itemizedlist>
     </para>
     </sect3>
diff --git a/doc/src/sgml/ref/create_foreign_table.sgml b/doc/src/sgml/ref/create_foreign_table.sgml
index 065c982082..12087ec05c 100644
--- a/doc/src/sgml/ref/create_foreign_table.sgml
+++ b/doc/src/sgml/ref/create_foreign_table.sgml
@@ -79,7 +79,9 @@ CHECK ( <replaceable class="PARAMETER">expression</replaceable> ) [ NO INHERIT ]
   <para>
    If <literal>PARTITION OF</literal> clause is specified then the table is
    created as a partition of <literal>parent_table</literal> with specified
-   bounds.
+   bounds.  Note that routing tuples to partitions that are foreign tables
+   is not supported. So, if an inserted tuple routes to one of foreign
+   partitions, an error will occur.
   </para>
 
   <para>
@@ -279,16 +281,19 @@ CHECK ( <replaceable class="PARAMETER">expression</replaceable> ) [ NO INHERIT ]
   <title>Notes</title>
 
    <para>
-    Constraints on foreign tables (such as <literal>CHECK</>
-    or <literal>NOT NULL</> clauses) are not enforced by the
-    core <productname>PostgreSQL</> system, and most foreign data wrappers
-    do not attempt to enforce them either; that is, the constraint is
+    Constraints (both the user-defined constraints such as <literal>CHECK</>
+    or <literal>NOT NULL</> clauses and the partition constraint) are not
+    enforced by the core <productname>PostgreSQL</> system, and most foreign
+    data wrappers do not attempt to enforce them either; that is, the they is
     simply assumed to hold true.  There would be little point in such
     enforcement since it would only apply to rows inserted or updated via
     the foreign table, and not to rows modified by other means, such as
     directly on the remote server.  Instead, a constraint attached to a
     foreign table should represent a constraint that is being enforced by
-    the remote server.
+    the remote server.  That becomes especially important if the table is
+    being used in a partition hierarchy, where it is recommended to add
+    a constraint matching the partition constraint expression on
+    the remote table.
    </para>
 
    <para>
-- 
2.11.0