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Add warning about DOMAINs.

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David Fetter
This commit is contained in:
Bruce Momjian 2005-09-22 23:56:46 +00:00
parent c79671bdbb
commit 0135cd88bd
1 changed files with 8 additions and 5 deletions
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13
doc/src/sgml/ref/create_domain.sgml
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@ -1,5 +1,5 @@
<!-- <!--
$PostgreSQL: pgsql/doc/src/sgml/ref/create_domain.sgml,v 1.22 2005/05/02 01:52:50 neilc Exp $ $PostgreSQL: pgsql/doc/src/sgml/ref/create_domain.sgml,v 1.23 2005/09/22 23:56:46 momjian Exp $
PostgreSQL documentation PostgreSQL documentation
--> -->
@ -48,10 +48,13 @@ where <replaceable class="PARAMETER">constraint</replaceable> is:
</para> </para>
<para> <para>
Domains are useful for abstracting common fields between tables into Domains are useful for abstracting common fields between tables
a single location for maintenance. For example, an email address column may be used into a single location for maintenance. For example, an email address
in several tables, all with the same properties. Define a domain and column may be used in several tables, all with the same properties.
use that rather than setting up each table's constraints individually. Define a domain and use that rather than setting up each table's
constraints individually. <note>Keep in mind also that declaring a
function result value as a domain is pretty dangerous, because none of
the PLs enforce domain constraints on their results.</note>
</para> </para>
</refsect1> </refsect1>