<!--
doc/src/sgml/ref/clusterdb.sgml
PostgreSQL documentation
-->

<refentry id="app-clusterdb">
 <indexterm zone="app-clusterdb">
  <primary>clusterdb</primary>
 </indexterm>

 <refmeta>
  <refentrytitle><application>clusterdb</application></refentrytitle>
  <manvolnum>1</manvolnum>
  <refmiscinfo>Application</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>clusterdb</refname>
  <refpurpose>cluster a <productname>PostgreSQL</productname> database</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
  <cmdsynopsis>
   <command>clusterdb</command>
   <arg rep="repeat"><replaceable>connection-option</replaceable></arg>
   <arg rep="repeat"><replaceable>option</replaceable></arg>

   <arg choice="plain" rep="repeat">
     <arg choice="opt">
       <group choice="plain">
         <arg choice="plain"><option>--table</option></arg>
         <arg choice="plain"><option>-t</option></arg>
       </group>
       <replaceable>table</replaceable>
     </arg>
   </arg>

   <arg choice="opt">
    <group choice="plain">
     <arg choice="plain"><replaceable>dbname</replaceable></arg>
     <arg choice="plain"><option>-a</option></arg>
     <arg choice="plain"><option>--all</option></arg>
    </group>
   </arg>
  </cmdsynopsis>
 </refsynopsisdiv>


 <refsect1>
  <title>Description</title>

  <para>
   <application>clusterdb</application> is a utility for reclustering tables
   in a <productname>PostgreSQL</productname> database.  It finds tables
   that have previously been clustered, and clusters them again on the same
   index that was last used.  Tables that have never been clustered are not
   affected.
  </para>

  <para>
   <application>clusterdb</application> is a wrapper around the SQL
   command <xref linkend="sql-cluster"/>.
   There is no effective difference between clustering databases via
   this utility and via other methods for accessing the server.
  </para>

 </refsect1>


 <refsect1>
  <title>Options</title>

   <para>
    <application>clusterdb</application> accepts the following command-line arguments:

    <variablelist>
     <varlistentry>
      <term><option>-a</option></term>
      <term><option>--all</option></term>
      <listitem>
       <para>
        Cluster all databases.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option><optional>-d</optional> <replaceable class="parameter">dbname</replaceable></option></term>
      <term><option><optional>--dbname=</optional><replaceable class="parameter">dbname</replaceable></option></term>
      <listitem>
       <para>
        Specifies the name of the database to be clustered,
        when <option>-a</option>/<option>--all</option> is not used.
        If this is not specified, the database name is read
        from the environment variable <envar>PGDATABASE</envar>.  If
        that is not set, the user name specified for the connection is
        used.  The <replaceable>dbname</replaceable> can be a <link
        linkend="libpq-connstring">connection string</link>.  If so,
        connection string parameters will override any conflicting command
        line options.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-e</option></term>
      <term><option>--echo</option></term>
      <listitem>
       <para>
        Echo the commands that <application>clusterdb</application> generates
        and sends to the server.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-q</option></term>
      <term><option>--quiet</option></term>
      <listitem>
       <para>
        Do not display progress messages.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-t <replaceable class="parameter">table</replaceable></option></term>
      <term><option>--table=<replaceable class="parameter">table</replaceable></option></term>
      <listitem>
       <para>
        Cluster <replaceable class="parameter">table</replaceable> only.
        Multiple tables can be clustered by writing multiple
        <option>-t</option> switches.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-v</option></term>
      <term><option>--verbose</option></term>
      <listitem>
       <para>
        Print detailed information during processing.
       </para>
      </listitem>
     </varlistentry>

    <varlistentry>
      <term><option>-V</option></term>
      <term><option>--version</option></term>
      <listitem>
      <para>
      Print the <application>clusterdb</application> version and exit.
      </para>
      </listitem>
    </varlistentry>

    <varlistentry>
      <term><option>-?</option></term>
      <term><option>--help</option></term>
      <listitem>
      <para>
      Show help about <application>clusterdb</application> command line
      arguments, and exit.
      </para>
      </listitem>
    </varlistentry>

    </variablelist>
   </para>

   <para>
    <application>clusterdb</application> also accepts
    the following command-line arguments for connection parameters:

    <variablelist>
     <varlistentry>
      <term><option>-h <replaceable class="parameter">host</replaceable></option></term>
      <term><option>--host=<replaceable class="parameter">host</replaceable></option></term>
      <listitem>
       <para>
        Specifies the host name of the machine on which the server is
        running.  If the value begins with a slash, it is used as the
        directory for the Unix domain socket.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-p <replaceable class="parameter">port</replaceable></option></term>
      <term><option>--port=<replaceable class="parameter">port</replaceable></option></term>
      <listitem>
       <para>
        Specifies the TCP port or local Unix domain socket file
        extension on which the server
        is listening for connections.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-U <replaceable class="parameter">username</replaceable></option></term>
      <term><option>--username=<replaceable class="parameter">username</replaceable></option></term>
      <listitem>
       <para>
        User name to connect as.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-w</option></term>
      <term><option>--no-password</option></term>
      <listitem>
       <para>
        Never issue a password prompt.  If the server requires
        password authentication and a password is not available by
        other means such as a <filename>.pgpass</filename> file, the
        connection attempt will fail.  This option can be useful in
        batch jobs and scripts where no user is present to enter a
        password.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-W</option></term>
      <term><option>--password</option></term>
      <listitem>
       <para>
        Force <application>clusterdb</application> to prompt for a
        password before connecting to a database.
       </para>

       <para>
        This option is never essential, since
        <application>clusterdb</application> will automatically prompt
        for a password if the server demands password authentication.
        However, <application>clusterdb</application> will waste a
        connection attempt finding out that the server wants a password.
        In some cases it is worth typing <option>-W</option> to avoid the extra
        connection attempt.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>--maintenance-db=<replaceable class="parameter">dbname</replaceable></option></term>
      <listitem>
       <para>
        Specifies the name of the database to connect to to discover which
        databases should be clustered,
        when <option>-a</option>/<option>--all</option> is used.
        If not specified, the <literal>postgres</literal> database will be used,
        or if that does not exist, <literal>template1</literal> will be used.
        This can be a <link linkend="libpq-connstring">connection
        string</link>.  If so, connection string parameters will override any
        conflicting command line options.  Also, connection string parameters
        other than the database name itself will be re-used when connecting
        to other databases.
       </para>
      </listitem>
     </varlistentry>
    </variablelist>
   </para>
 </refsect1>


 <refsect1>
  <title>Environment</title>

  <variablelist>
   <varlistentry>
    <term><envar>PGDATABASE</envar></term>
    <term><envar>PGHOST</envar></term>
    <term><envar>PGPORT</envar></term>
    <term><envar>PGUSER</envar></term>

    <listitem>
     <para>
      Default connection parameters
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><envar>PG_COLOR</envar></term>
    <listitem>
     <para>
      Specifies whether to use color in diagnostic messages. Possible values
      are <literal>always</literal>, <literal>auto</literal> and
      <literal>never</literal>.
     </para>
    </listitem>
   </varlistentry>
  </variablelist>

  <para>
   This utility, like most other <productname>PostgreSQL</productname> utilities,
   also uses the environment variables supported by <application>libpq</application>
   (see <xref linkend="libpq-envars"/>).
  </para>

 </refsect1>


 <refsect1>
  <title>Diagnostics</title>

  <para>
   In case of difficulty, see <xref linkend="sql-cluster"/>
   and <xref linkend="app-psql"/> for
   discussions of potential problems and error messages.
   The database server must be running at the
   targeted host.  Also, any default connection settings and environment
   variables used by the <application>libpq</application> front-end
   library will apply.
  </para>

 </refsect1>


 <refsect1>
  <title>Examples</title>

   <para>
    To cluster the database <literal>test</literal>:
<screen>
<prompt>$ </prompt><userinput>clusterdb test</userinput>
</screen>
   </para>

   <para>
    To cluster a single table
    <literal>foo</literal> in a database named
    <literal>xyzzy</literal>:
<screen>
<prompt>$ </prompt><userinput>clusterdb --table=foo xyzzy</userinput>
</screen></para>

 </refsect1>

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

  <simplelist type="inline">
   <member><xref linkend="sql-cluster"/></member>
  </simplelist>
 </refsect1>

</refentry>
