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| -rw-r--r-- | doc/src/sgml/ddl.sgml | 32 |
1 files changed, 31 insertions, 1 deletions
diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml index 01f9acfd23e..334ad51082c 100644 --- a/doc/src/sgml/ddl.sgml +++ b/doc/src/sgml/ddl.sgml @@ -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"> <title>Data Definition</title> @@ -845,6 +845,36 @@ CREATE TABLE order_items ( <xref linkend="sql-createtable" endterm="sql-createtable-title">. </para> </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 &&) +); +</programlisting> + </para> + + <para> + See also <link linkend="SQL-CREATETABLE-EXCLUDE"><command>CREATE + TABLE ... CONSTRAINT ... EXCLUDE</></link> for details. + </para> + </sect2> </sect1> <sect1 id="ddl-system-columns"> |