doc/src/sgml/ref/create_tablespace.sgml

<!--
doc/src/sgml/ref/create_tablespace.sgml
PostgreSQL documentation
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<refentry id="sql-createtablespace">
 <indexterm zone="sql-createtablespace">
  <primary>CREATE TABLESPACE</primary>
 </indexterm>

 <refmeta>
  <refentrytitle>CREATE TABLESPACE</refentrytitle>
  <manvolnum>7</manvolnum>
  <refmiscinfo>SQL - Language Statements</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>CREATE TABLESPACE</refname>
  <refpurpose>define a new tablespace</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
<synopsis>
CREATE TABLESPACE <replaceable class="parameter">tablespace_name</replaceable>
    [ OWNER { <replaceable>new_owner</replaceable> | CURRENT_ROLE | CURRENT_USER | SESSION_USER } ]
    LOCATION '<replaceable class="parameter">directory</replaceable>'
    [ WITH ( <replaceable class="parameter">tablespace_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] ) ]
</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <command>CREATE TABLESPACE</command> registers a new cluster-wide
   tablespace.  The tablespace name must be distinct from the name of any
   existing tablespace in the database cluster.
  </para>

  <para>
   A tablespace allows superusers to define an alternative location on
   the file system where the data files containing database objects
   (such as tables and indexes) can reside.
  </para>

  <para>
   A user with appropriate privileges can pass
   <replaceable class="parameter">tablespace_name</replaceable> to
   <command>CREATE DATABASE</command>, <command>CREATE TABLE</command>,
   <command>CREATE INDEX</command> or <command>ADD CONSTRAINT</command> to have the data
   files for these objects stored within the specified tablespace.
  </para>

  <warning>
   <para>
    A tablespace cannot be used independently of the cluster in which it
    is defined;  see <xref linkend="manage-ag-tablespaces"/>.
   </para>
  </warning>

 </refsect1>

 <refsect1>
  <title>Parameters</title>

    <variablelist>
     <varlistentry>
      <term><replaceable class="parameter">tablespace_name</replaceable></term>
      <listitem>
       <para>
        The name of a tablespace to be created.  The name cannot
        begin with <literal>pg_</literal>, as such names
        are reserved for system tablespaces.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><replaceable class="parameter">user_name</replaceable></term>
      <listitem>
       <para>
        The name of the user who will own the tablespace.  If omitted,
        defaults to the user executing the command.  Only superusers
        can create tablespaces, but they can assign ownership of tablespaces
        to non-superusers.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><replaceable class="parameter">directory</replaceable></term>
      <listitem>
       <para>
        The directory that will be used for the tablespace. The directory
        must exist (<command>CREATE TABLESPACE</command> will not create it),
        should be empty, and must be owned by the
        <productname>PostgreSQL</productname> system user.  The directory must be
        specified by an absolute path name.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><replaceable class="parameter">tablespace_option</replaceable></term>
      <listitem>
       <para>
        A tablespace parameter to be set or reset.  Currently, the only
        available parameters are <varname>seq_page_cost</varname>,
        <varname>random_page_cost</varname>, <varname>effective_io_concurrency</varname>
        and <varname>maintenance_io_concurrency</varname>.
        Setting these values for a particular tablespace will override the
        planner's usual estimate of the cost of reading pages from tables in
        that tablespace, and the executor's prefetching behavior, as established
        by the configuration parameters of the
        same name (see <xref linkend="guc-seq-page-cost"/>,
        <xref linkend="guc-random-page-cost"/>,
        <xref linkend="guc-effective-io-concurrency"/>,
        <xref linkend="guc-maintenance-io-concurrency"/>).  This may be useful if
        one tablespace is located on a disk which is faster or slower than the
        remainder of the I/O subsystem.
       </para>
      </listitem>
     </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1>
  <title>Notes</title>

  <para>
   Tablespaces are only supported on systems that support symbolic links.
  </para>

   <para>
    <command>CREATE TABLESPACE</command> cannot be executed inside a transaction
    block.
   </para>
 </refsect1>

 <refsect1>
  <title>Examples</title>

  <para>
   To create a tablespace <literal>dbspace</literal> at file system location
   <literal>/data/dbs</literal>, first create the directory using operating
   system facilities and set the correct ownership:
<programlisting>
mkdir /data/dbs
chown postgres:postgres /data/dbs
</programlisting>
   Then issue the tablespace creation command inside
   <productname>PostgreSQL</productname>:
<programlisting>
CREATE TABLESPACE dbspace LOCATION '/data/dbs';
</programlisting>
  </para>

  <para>
   To create a tablespace owned by a different database user, use a command
   like this:
<programlisting>
CREATE TABLESPACE indexspace OWNER genevieve LOCATION '/data/indexes';
</programlisting></para>
 </refsect1>

 <refsect1>
  <title>Compatibility</title>

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

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

  <simplelist type="inline">
   <member><xref linkend="sql-createdatabase"/></member>
   <member><xref linkend="sql-createtable"/></member>
   <member><xref linkend="sql-createindex"/></member>
   <member><xref linkend="sql-droptablespace"/></member>
   <member><xref linkend="sql-altertablespace"/></member>
  </simplelist>
 </refsect1>

</refentry>