reset.sgml

来自「postgresql8.3.4源码,开源数据库」· SGML 代码 · 共 114 行

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$PostgreSQL: pgsql/doc/src/sgml/ref/reset.sgml,v 1.36 2007/09/11 00:06:41 tgl Exp $
PostgreSQL documentation
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<refentry id="SQL-RESET">
 <refmeta>
  <refentrytitle id="SQL-RESET-TITLE">RESET</refentrytitle>
  <refmiscinfo>SQL - Language Statements</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>RESET</refname>
  <refpurpose>restore the value of a run-time parameter to the default value</refpurpose>
 </refnamediv>

 <indexterm zone="sql-reset">
  <primary>RESET</primary>
 </indexterm>

 <refsynopsisdiv>
<synopsis>
RESET <replaceable class="PARAMETER">configuration_parameter</replaceable>
RESET ALL
</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <command>RESET</command> restores run-time parameters to their
   default values.  <command>RESET</command> is an alternative
   spelling for
<synopsis>
SET <replaceable class="parameter">configuration_parameter</replaceable> TO DEFAULT
</synopsis>
   Refer to <xref linkend="sql-set" endterm="sql-set-title"> for
   details.
  </para>

  <para>
   The default value is defined as the value that the parameter would
   have had, if no <command>SET</> had ever been issued for it in the
   current session.  The actual source of this value might be a
   compiled-in default, the configuration file, command-line options,
   or per-database or per-user default settings.  This is subtly different
   from defining it as <quote>the value that the parameter had at session
   start</>, because if the value came from the configuration file, it
   will be reset to whatever is specified by the configuration file now.
   See <xref linkend="runtime-config"> for details.
  </para>

  <para>
   The transactional behavior of <command>RESET</> is the same as
   <command>SET</>: its effects will be undone by transaction rollback.
  </para>
 </refsect1>

 <refsect1>
  <title>Parameters</title>

  <variablelist>
   <varlistentry>
    <term><replaceable class="PARAMETER">configuration_parameter</replaceable></term>
    <listitem>
     <para>
      Name of a settable run-time parameter.  Available parameters are
      documented in <xref linkend="runtime-config"> and on the
      <xref linkend="sql-set" endterm="sql-set-title"> reference page.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><literal>ALL</literal></term>
    <listitem>
     <para>
      Resets all settable run-time parameters to default values.
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1>
  <title>Examples</title>

  <para>
   Set the <varname>timezone</> configuration variable to its default value:
<screen>
RESET timezone;
</screen>
  </para>
 </refsect1>

 <refsect1>
  <title>Compatibility</title>

  <para>
   <command>RESET</command> is a <productname>PostgreSQL</productname> extension.
  </para>
 </refsect1>

 <refsect1>
  <title>See Also</title>

  <simplelist type="inline">
   <member><xref linkend="SQL-SET" endterm="SQL-SET-title"></member>
   <member><xref linkend="SQL-SHOW" endterm="SQL-SHOW-title"></member>
  </simplelist>
 </refsect1>
</refentry>