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Add contraint exclusion section to contraint docs.

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Takahiro Itagaki
This commit is contained in:
Bruce Momjian 2010-04-01 01:18:17 +00:00
parent 54943734f8
commit 0189c42f31
1 changed files with 31 additions and 1 deletions
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doc/src/sgml/ddl.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/ddl.sgml,v 1.90 2010/02/24 15:54:31 momjian Exp $ --> <!-- $PostgreSQL: pgsql/doc/src/sgml/ddl.sgml,v 1.91 2010/04/01 01:18:17 momjian Exp $ -->
<chapter id="ddl"> <chapter id="ddl">
<title>Data Definition</title> <title>Data Definition</title>
@ -845,6 +845,36 @@ CREATE TABLE order_items (
<xref linkend="sql-createtable" endterm="sql-createtable-title">. <xref linkend="sql-createtable" endterm="sql-createtable-title">.
</para> </para>
</sect2> </sect2>
<sect2>
<title>Exclusion constraints</title>
<indexterm>
<primary>exclusion constraint</primary>
</indexterm>
<indexterm>
<primary>constraint</primary>
<secondary>exclusion</secondary>
</indexterm>
<para>
Exclusion constraints ensure that if any two rows are compared on
the specified columns or expressions using the specified operators,
at least one of these operator comparisons will be false. The syntax is:
<programlisting>
CREATE TABLE circles (
c circle,
EXCLUDE USING gist (c WITH &amp;&amp;)
);
</programlisting>
</para>
<para>
See also <link linkend="SQL-CREATETABLE-EXCLUDE"><command>CREATE
TABLE ... CONSTRAINT ... EXCLUDE</></link> for details.
</para>
</sect2>
</sect1> </sect1>
<sect1 id="ddl-system-columns"> <sect1 id="ddl-system-columns">