truncate.sgml

PostgreSQL7.4.6 for Linux

<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/truncate.sgml,v 1.15 2003/09/19 21:06:39 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>
   <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>

<!-- Keep this comment at the end of the file
Local variables:
mode: sgml
sgml-omittag:t
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
sgml-parent-document:nil
sgml-default-dtd-file:"../reference.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:"/usr/lib/sgml/catalog"
sgml-local-ecat-files:nil
End:
-->