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Diffstat (limited to 'doc/src/sgml/ref/set_constraints.sgml')
| -rw-r--r-- | doc/src/sgml/ref/set_constraints.sgml | 83 |
1 files changed, 39 insertions, 44 deletions
diff --git a/doc/src/sgml/ref/set_constraints.sgml b/doc/src/sgml/ref/set_constraints.sgml index 32abdee89f3..3d5b58bee2e 100644 --- a/doc/src/sgml/ref/set_constraints.sgml +++ b/doc/src/sgml/ref/set_constraints.sgml @@ -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"> - <title>Compatibility</title> + <refsect1> + <title>Notes</title> - <refsect2 id="R2-SQL-SET-CONSTRAINT-4"> - <title>SQL92, SQL99</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> - <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> |