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<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/truncate.sgml,v 1.15.2.1 2005/02/22 19:06:49 tgl Exp $
PostgreSQL documentation
-->
<refentry id="SQL-TRUNCATE">
<refmeta>
<refentrytitle id="SQL-TRUNCATE-TITLE">TRUNCATE</refentrytitle>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>TRUNCATE</refname>
<refpurpose>empty a table</refpurpose>
</refnamediv>
<indexterm zone="sql-truncate">
<primary>TRUNCATE</primary>
</indexterm>
<refsynopsisdiv>
<synopsis>
TRUNCATE [ TABLE ] <replaceable class="PARAMETER">name</replaceable>
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>TRUNCATE</command> quickly removes all rows from a
table. It has the same effect as an unqualified
<command>DELETE</command> but since it does not actually scan the
table it is faster. This is most useful on large tables.
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><replaceable class="PARAMETER">name</replaceable></term>
<listitem>
<para>
The name (optionally schema-qualified) of the table to be truncated.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<para>
Only the owner of a table may <command>TRUNCATE</> it.
</para>
<para>
<command>TRUNCATE</> cannot be used if there are foreign-key references
to the table from other tables. Checking validity in such cases would
require table scans, and the whole point is not to do one.
</para>
<para>
<command>TRUNCATE</> will not run any user-defined ON DELETE triggers
that might exist for the table.
</para>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
Truncate the table <literal>bigtable</literal>:
<programlisting>
TRUNCATE TABLE bigtable;
</programlisting>
</para>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para>
There is no <command>TRUNCATE</command> command in the SQL standard.
</para>
</refsect1>
</refentry>
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Local variables:
mode: sgml
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sgml-always-quote-attributes:t
sgml-indent-step:1
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sgml-default-dtd-file:"../reference.ced"
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sgml-local-catalogs:"/usr/lib/sgml/catalog"
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