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Last round of reference page editing.

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Peter Eisentraut
2003-05-04 02:23:16 +00:00
parent ac5fdea687
commit d1b4327d02
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doc/src/sgml/ref/set_constraints.sgml
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@@ -1,20 +1,19 @@
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/ref/set_constraints.sgml,v 1.5 2002/08/17 12:15:48 momjian Exp $ -->
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/ref/set_constraints.sgml,v 1.6 2003/05/04 02:23:16 petere Exp $ -->
<refentry id="SQL-SET-CONSTRAINTS">
<refmeta>
<refentrytitle id="SQL-SET-CONSTRAINTS-title">SET CONSTRAINTS</refentrytitle>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>SET CONSTRAINTS</refname>
<refpurpose>set the constraint mode of the current transaction</refpurpose>
</refnamediv>
<refsynopsisdiv>
<refsynopsisdivinfo>
<date>2000-06-01</date>
</refsynopsisdivinfo>
<synopsis>
<synopsis>
SET CONSTRAINTS { ALL | <replaceable class="parameter">constraint</replaceable> [, ...] } { DEFERRED | IMMEDIATE }
</synopsis>
</synopsis>
</refsynopsisdiv>
<refsect1>
@@ -22,39 +21,26 @@ SET CONSTRAINTS { ALL | <replaceable class="parameter">constraint</replaceable>
<para>
<command>SET CONSTRAINTS</command> sets the behavior of constraint
evaluation in the current transaction. In <option>IMMEDIATE
</option> mode, constraints are checked at the end of each
statement. In <option>DEFERRED</option> mode, constraints are not
checked until transaction commit.
evaluation in the current transaction. In
<literal>IMMEDIATE</literal> mode, constraints are checked at the
end of each statement. In <literal>DEFERRED</literal> mode,
constraints are not checked until transaction commit.
</para>
<note>
<para>
This command only alters the behavior of constraints within the
current transaction. Thus, if you execute this command outside
of an explicit transaction block (such as one started with
<command>BEGIN</command>), it will not appear to have any effect.
If you wish to change the behavior of a constraint without needing
to issue a <command>SET CONSTRAINTS</command> command in every
transaction, specify <option>INITIALLY DEFERRED</option> or
<option>INITIALLY IMMEDIATE</option> when you create the constraint.
</para>
</note>
<para>
When you change the mode of a constraint to be <option>IMMEDIATE
</option>, the new constraint mode takes effect retroactively:
any outstanding data modifications that would have been checked
at the end of the transaction (when using
<option>DEFERRED</option>) are instead checked during the
When you change the mode of a constraint to be
<literal>IMMEDIATE</literal>, the new constraint mode takes effect
retroactively: any outstanding data modifications that would have
been checked at the end of the transaction (when using
<literal>DEFERRED</literal>) are instead checked during the
execution of the <command>SET CONSTRAINTS</command> command.
</para>
<para>
Upon creation, a constraint is always give one of three
characteristics: <option>INITIALLY DEFERRED</option>,
<option>INITIALLY IMMEDIATE DEFERRABLE</option>, or
<option>INITIALLY IMMEDIATE NOT DEFERRABLE</option>. The third
characteristics: <literal>INITIALLY DEFERRED</literal>,
<literal>INITIALLY IMMEDIATE DEFERRABLE</literal>, or
<literal>INITIALLY IMMEDIATE NOT DEFERRABLE</literal>. The third
class is not affected by the <command>SET CONSTRAINTS</command>
command.
</para>
@@ -66,21 +52,30 @@ SET CONSTRAINTS { ALL | <replaceable class="parameter">constraint</replaceable>
</para>
</refsect1>
<refsect1 id="R1-SQL-SET-CONSTRAINT-3">
<refsect1>
<title>Notes</title>
<para>
This command only alters the behavior of constraints within the
current transaction. Thus, if you execute this command outside of a
transaction block
(<command>BEGIN</command>/<command>COMMIT</command> pair), it will
not appear to have any effect. If you wish to change the behavior
of a constraint without needing to issue a <command>SET
CONSTRAINTS</command> command in every transaction, specify
<literal>INITIALLY DEFERRED</literal> or <literal>INITIALLY
IMMEDIATE</literal> when you create the constraint.
</para>
</refsect1>
<refsect1>
<title>Compatibility</title>
<refsect2 id="R2-SQL-SET-CONSTRAINT-4">
<title>SQL92, SQL99</title>
<para>
<command>SET CONSTRAINTS</command> is defined in
<acronym>SQL92</acronym> and <acronym>SQL99</acronym>. The
implementation in <productname>PostgreSQL</productname> complies
with the behavior defined in the standard, except for the
<productname>PostgreSQL</productname> limitation that <command>SET
CONSTRAINTS</command> cannot be applied to check or unique constraints.
</para>
</refsect2>
<para>
This command complies with the behavior defined in the SQL
standard, except for the limitation that, in PostgreSQL, it only
applies to foreign-key constraints.
</para>
</refsect1>
</refentry>