<!--
doc/src/sgml/ref/create_foreign_data_wrapper.sgml
PostgreSQL documentation
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<refentry id="sql-createforeigndatawrapper">
 <indexterm zone="sql-createforeigndatawrapper">
  <primary>CREATE FOREIGN DATA WRAPPER</primary>
 </indexterm>

 <refmeta>
  <refentrytitle>CREATE FOREIGN DATA WRAPPER</refentrytitle>
  <manvolnum>7</manvolnum>
  <refmiscinfo>SQL - Language Statements</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>CREATE FOREIGN DATA WRAPPER</refname>
  <refpurpose>define a new foreign-data wrapper</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
<synopsis>
CREATE FOREIGN DATA WRAPPER <replaceable class="parameter">name</replaceable>
    [ HANDLER <replaceable class="parameter">handler_function</replaceable> | NO HANDLER ]
    [ VALIDATOR <replaceable class="parameter">validator_function</replaceable> | NO VALIDATOR ]
    [ OPTIONS ( <replaceable class="parameter">option</replaceable> '<replaceable class="parameter">value</replaceable>' [, ... ] ) ]
</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <command>CREATE FOREIGN DATA WRAPPER</command> creates a new
   foreign-data wrapper.  The user who defines a foreign-data wrapper
   becomes its owner.
  </para>

  <para>
   The foreign-data wrapper name must be unique within the database.
  </para>

  <para>
   Only superusers can create foreign-data wrappers.
  </para>
 </refsect1>

 <refsect1>
  <title>Parameters</title>

  <variablelist>
   <varlistentry>
    <term><replaceable class="parameter">name</replaceable></term>
    <listitem>
     <para>
      The name of the foreign-data wrapper to be created.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><literal>HANDLER <replaceable class="parameter">handler_function</replaceable></literal></term>
    <listitem>
     <para><replaceable class="parameter">handler_function</replaceable> is the
      name of a previously registered function that will be called to
      retrieve the execution functions for foreign tables.
      The handler function must take no arguments, and
      its return type must be <type>fdw_handler</type>.
     </para>

     <para>
      It is possible to create a foreign-data wrapper with no handler
      function, but foreign tables using such a wrapper can only be declared,
      not accessed.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><literal>VALIDATOR <replaceable class="parameter">validator_function</replaceable></literal></term>
    <listitem>
     <para><replaceable class="parameter">validator_function</replaceable>
      is the name of a previously registered function that will be called to
      check the generic options given to the foreign-data wrapper, as
      well as options for foreign servers, user mappings and foreign tables
      using the foreign-data wrapper.  If no validator function or <literal>NO
      VALIDATOR</literal> is specified, then options will not be
      checked at creation time.  (Foreign-data wrappers will possibly
      ignore