From 04ef4040186ac08b78ef0c88b78df3b0af4d6346 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Mon, 18 Jan 2010 00:32:21 +0000
Subject: [PATCH] Update SET CONSTRAINTS reference page --- it failed to
 mention EXCLUDE constraints and was lacking a couple of other interesting
 details.

---
 doc/src/sgml/ref/set_constraints.sgml | 35 +++++++++++++++++++--------
 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/doc/src/sgml/ref/set_constraints.sgml b/doc/src/sgml/ref/set_constraints.sgml
index e03910e252..94c2ecabc7 100644
--- a/doc/src/sgml/ref/set_constraints.sgml
+++ b/doc/src/sgml/ref/set_constraints.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/ref/set_constraints.sgml,v 1.17 2009/07/29 20:56:17 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/ref/set_constraints.sgml,v 1.18 2010/01/18 00:32:21 tgl Exp $ -->
 <refentry id="SQL-SET-CONSTRAINTS">
  <refmeta>
   <refentrytitle id="SQL-SET-CONSTRAINTS-title">SET CONSTRAINTS</refentrytitle>
@@ -8,7 +8,7 @@
 
  <refnamediv>
   <refname>SET CONSTRAINTS</refname>
-  <refpurpose>set constraint checking modes for the current transaction</refpurpose>
+  <refpurpose>set constraint check timing for the current transaction</refpurpose>
  </refnamediv>
 
  <indexterm zone="sql-set-constraints">
@@ -46,7 +46,8 @@ SET CONSTRAINTS { ALL | <replaceable class="parameter">name</replaceable> [, ...
 
   <para>
    <command>SET CONSTRAINTS</command> with a list of constraint names changes
-   the mode of just those constraints (which must all be deferrable).  The
+   the mode of just those constraints (which must all be deferrable).  Each
+   constraint name can be schema-qualified.  The
    current schema search path is used to find the first matching name if
    no schema name is specified.  <command>SET CONSTRAINTS ALL</command>
    changes the mode of all deferrable constraints.
@@ -66,13 +67,14 @@ SET CONSTRAINTS { ALL | <replaceable class="parameter">name</replaceable> [, ...
   </para>
 
   <para>
-   Currently, only <literal>UNIQUE</>, <literal>PRIMARY KEY</>, and
-   <literal>REFERENCES</> (foreign key) constraints are affected by this
-   setting.  <literal>NOT NULL</> and <literal>CHECK</> constraints are
+   Currently, only <literal>UNIQUE</>, <literal>PRIMARY KEY</>,
+   <literal>REFERENCES</> (foreign key), and <literal>EXCLUDE</>
+   constraints are affected by this setting.
+   <literal>NOT NULL</> and <literal>CHECK</> constraints are
    always checked immediately when a row is inserted or modified
    (<emphasis>not</> at the end of the statement).
-   Uniqueness constraints that have not been declared <literal>DEFERRABLE</>
-   are also checked immediately.
+   Uniqueness and exclusion constraints that have not been declared
+   <literal>DEFERRABLE</> are also checked immediately.
   </para>
 
   <para>
@@ -85,6 +87,16 @@ SET CONSTRAINTS { ALL | <replaceable class="parameter">name</replaceable> [, ...
  <refsect1>
   <title>Notes</title>
 
+  <para>
+   Because <productname>PostgreSQL</productname> does not require constraint
+   names to be unique within a schema (but only per-table), it is possible
+   that there is more than one match for a specified constraint name.
+   In this case <command>SET CONSTRAINTS</command> will act on all matches.
+   For a non-schema-qualified name, once a match or matches have been found in
+   some schema in the search path, schemas appearing later in the path are not
+   searched.
+  </para>
+
   <para>
    This command only alters the behavior of constraints within the
    current transaction. Thus, if you execute this command outside of a
@@ -100,8 +112,11 @@ SET CONSTRAINTS { ALL | <replaceable class="parameter">name</replaceable> [, ...
   <para>
    This command complies with the behavior defined in the SQL
    standard, except for the limitation that, in
-   <productname>PostgreSQL</productname>, it only applies to
-   foreign-key and uniqueness constraints.
+   <productname>PostgreSQL</productname>, it does not apply to
+   <literal>NOT NULL</> and <literal>CHECK</> constraints.
+   Also, <productname>PostgreSQL</productname> checks non-deferrable
+   uniqueness constraints immediately, not at end of statement as the
+   standard would suggest.
   </para>
 
  </refsect1>