<!--
doc/src/sgml/ref/create_materialized_view.sgml
PostgreSQL documentation
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<refentry id="sql-creatematerializedview">
 <indexterm zone="sql-creatematerializedview">
  <primary>CREATE MATERIALIZED VIEW</primary>
 </indexterm>

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

 <refnamediv>
  <refname>CREATE MATERIALIZED VIEW</refname>
  <refpurpose>define a new materialized view</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
<synopsis>
CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    [ (<replaceable>column_name</replaceable> [, ...] ) ]
    [ USING <replaceable class="parameter">method</replaceable> ]
    [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
    [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
    AS <replaceable>query</replaceable>
    [ WITH [ NO ] DATA ]
</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
   a query.  The query is executed and used to populate the view at the time
   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
   refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
  </para>

  <para>
   <command>CREATE MATERIALIZED VIEW</command> is similar to
   <command>CREATE TABLE AS</command>, except that it also remembers the query used
   to initialize the view, so that it can be refreshed later upon demand.
   A materialized view has many of the same properties as a table, but there
   is no support for temporary materialized views.
  </para>
 </refsect1>

 <refsect1>
  <title>Parameters</title>

  <variablelist>
   <varlistentry>
    <term><literal>IF NOT EXISTS</literal></term>
    <listitem>
     <para>
      Do not throw an error if a materialized view with the same name already
      exists. A notice is issued in this case.  Note that there is no guarantee
      that the existing materialized view is anything like the one that would
      have been created.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable>table_name</replaceable></term>
    <listitem>
     <para>
      The name (optionally schema-qualified) of the materialized view to be
      created.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable>column_name</replaceable></term>
    <listitem>
     <para>
      The name of a column in the new materialized view.  If column names are
      not provided, they are taken from the output column names of the query.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><literal>USING <replaceable class="parameter">method</replaceable></literal></term>
    <listitem>
     <para>
      This optional clause specifies the table access method to use to store
      the contents for the new materialized view; the method needs be an
      access method of type <literal>TABLE</literal>. See <xref
      linkend="tableam"/> for more information.  If this option is not
      specified, the default table access method is chosen for the new
      materialized view. See <xref linkend="guc-default-table-access-method"/>
      for more information.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><literal>WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] )</literal></term>
    <listitem>
     <para>
      This clause specifies optional storage parameters for the new
      materialized view; see
      <xref linkend="sql-createtable-storage-parameters"/> in the
      <xref linkend="sql-createtable"/> documentation for more
      information.  All parameters supported for <literal>CREATE
      TABLE</literal> are also supported for <literal>CREATE MATERIALIZED
      VIEW</literal>.
      See <xref linkend="sql-createtable"/> for more information.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><literal>TABLESPACE <replaceable class="parameter">tablespace_name</replaceable></literal></term>
    <listitem>
     <para>
      The <replaceable class="parameter">tablespace_name</replaceable> is the name
      of the tablespace in which the new materialized view is to be created.
      If not specified, <xref linkend="guc-default-tablespace"/> is consulted.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable>query</replaceable></term>
    <listitem>
     <para>
      A <link linkend="sql-select"><command>SELECT</command></link>, <link linkend="sql-table"><command>TABLE</command></link>,
      or <link linkend="sql-values"><command>VALUES</command></link> command.  This query will run within a
      security-restricted operation; in particular, calls to functions that
      themselves create temporary tables will fail.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><literal>WITH [ NO ] DATA</literal></term>
    <listitem>
     <para>
      This clause specifies whether or not the materialized view should be
      populated at creation time.  If not, the materialized view will be
      flagged as unscannable and cannot be queried until <command>REFRESH
      MATERIALIZED VIEW</command> is used.
     </para>
    </listitem>
   </varlistentry>

  </variablelist>
 </refsect1>

 <refsect1>
  <title>Compatibility</title>

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

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

  <simplelist type="inline">
   <member><xref linkend="sql-altermaterializedview"/></member>
   <member><xref linkend="sql-createtableas"/></member>
   <member><xref linkend="sql-createview"/></member>
   <member><xref linkend="sql-dropmaterializedview"/></member>
   <member><xref linkend="sql-refreshmaterializedview"/></member>
  </simplelist>
 </refsect1>

</refentry>
