1- <!-- $PostgreSQL: pgsql/doc/src/sgml/ref/set_constraints.sgml,v 1.17 2009/07/29 20:56:17 tgl Exp $ -->
1+ <!-- $PostgreSQL: pgsql/doc/src/sgml/ref/set_constraints.sgml,v 1.18 2010/01/18 00:32:21 tgl Exp $ -->
22<refentry id="SQL-SET-CONSTRAINTS">
33 <refmeta>
44 <refentrytitle id="SQL-SET-CONSTRAINTS-title">SET CONSTRAINTS</refentrytitle>
88
99 <refnamediv>
1010 <refname>SET CONSTRAINTS</refname>
11- <refpurpose>set constraintchecking modes for the current transaction</refpurpose>
11+ <refpurpose>set constraintcheck timing for the current transaction</refpurpose>
1212 </refnamediv>
1313
1414 <indexterm zone="sql-set-constraints">
@@ -46,7 +46,8 @@ SET CONSTRAINTS { ALL | <replaceable class="parameter">name</replaceable> [, ...
4646
4747 <para>
4848 <command>SET CONSTRAINTS</command> with a list of constraint names changes
49- the mode of just those constraints (which must all be deferrable). The
49+ the mode of just those constraints (which must all be deferrable). Each
50+ constraint name can be schema-qualified. The
5051 current schema search path is used to find the first matching name if
5152 no schema name is specified. <command>SET CONSTRAINTS ALL</command>
5253 changes the mode of all deferrable constraints.
@@ -66,13 +67,14 @@ SET CONSTRAINTS { ALL | <replaceable class="parameter">name</replaceable> [, ...
6667 </para>
6768
6869 <para>
69- Currently, only <literal>UNIQUE</>, <literal>PRIMARY KEY</>, and
70- <literal>REFERENCES</> (foreign key) constraints are affected by this
71- setting. <literal>NOT NULL</> and <literal>CHECK</> constraints are
70+ Currently, only <literal>UNIQUE</>, <literal>PRIMARY KEY</>,
71+ <literal>REFERENCES</> (foreign key), and <literal>EXCLUDE</>
72+ constraints are affected by this setting.
73+ <literal>NOT NULL</> and <literal>CHECK</> constraints are
7274 always checked immediately when a row is inserted or modified
7375 (<emphasis>not</> at the end of the statement).
74- Uniqueness constraints that have not been declared <literal>DEFERRABLE</>
75- are also checked immediately.
76+ Uniquenessand exclusion constraints that have not been declared
77+ <literal>DEFERRABLE</> are also checked immediately.
7678 </para>
7779
7880 <para>
@@ -85,6 +87,16 @@ SET CONSTRAINTS { ALL | <replaceable class="parameter">name</replaceable> [, ...
8587 <refsect1>
8688 <title>Notes</title>
8789
90+ <para>
91+ Because <productname>PostgreSQL</productname> does not require constraint
92+ names to be unique within a schema (but only per-table), it is possible
93+ that there is more than one match for a specified constraint name.
94+ In this case <command>SET CONSTRAINTS</command> will act on all matches.
95+ For a non-schema-qualified name, once a match or matches have been found in
96+ some schema in the search path, schemas appearing later in the path are not
97+ searched.
98+ </para>
99+
88100 <para>
89101 This command only alters the behavior of constraints within the
90102 current transaction. Thus, if you execute this command outside of a
@@ -100,8 +112,11 @@ SET CONSTRAINTS { ALL | <replaceable class="parameter">name</replaceable> [, ...
100112 <para>
101113 This command complies with the behavior defined in the SQL
102114 standard, except for the limitation that, in
103- <productname>PostgreSQL</productname>, it only applies to
104- foreign-key and uniqueness constraints.
115+ <productname>PostgreSQL</productname>, it does not apply to
116+ <literal>NOT NULL</> and <literal>CHECK</> constraints.
117+ Also, <productname>PostgreSQL</productname> checks non-deferrable
118+ uniqueness constraints immediately, not at end of statement as the
119+ standard would suggest.
105120 </para>
106121
107122 </refsect1>