standard SQL
    syntax, but specifying column types is a <productname>PostgreSQL</productname>
    extension.)  This allows the system to understand what
    <literal>*</literal> should expand to, and what <structname>proname</structname>
    in the <literal>WHERE</literal> clause refers to, in advance of trying
    to execute the function.  At run time, an error will be thrown
    if the actual query result from the remote database does not
    have the same number of columns shown in the <literal>FROM</literal> clause.
    The column names need not match, however, and <function>dblink</function>
    does not insist on exact type matches either.  It will succeed
    so long as the returned data strings are valid input for the
    column type declared in the <literal>FROM</literal> clause.
   </para>
  </refsect1>

  <refsect1>
   <title>Notes</title>

   <para>
    A convenient way to use <function>dblink</function> with predetermined
    queries is to create a view.
    This allows the column type information to be buried in the view,
    instead of having to spell it out in every query.  For example,

<programlisting>
CREATE VIEW myremote_pg_proc AS
  SELECT *
    FROM dblink('dbname=postgres options=-csearch_path=',
                'select proname, prosrc from pg_proc')
    AS t1(proname name, prosrc text);

SELECT * FROM myremote_pg_proc WHERE proname LIKE 'bytea%';
</programlisting></para>
  </refsect1>

  <refsect1>
   <title>Examples</title>

<screen>
SELECT * FROM dblink('dbname=postgres options=-csearch_path=',
                     'select proname, prosrc from pg_proc')
  AS t1(proname name, prosrc text) WHERE proname LIKE 'bytea%';
  proname   |   prosrc
------------+------------
 byteacat   | byteacat
 byteaeq    | byteaeq
 bytealt    | bytealt
 byteale    | byteale
 byteagt    | byteagt
 byteage    | byteage
 byteane    | byteane
 byteacmp   | byteacmp
 bytealike  | bytealike
 byteanlike | byteanlike
 byteain    | byteain
 byteaout   | byteaout
(12 rows)

SELECT dblink_connect('dbname=postgres options=-csearch_path=');
 dblink_connect
----------------
 OK
(1 row)

SELECT * FROM dblink('select proname, prosrc from pg_proc')
  AS t1(proname name, prosrc text) WHERE proname LIKE 'bytea%';
  proname   |   prosrc
------------+------------
 byteacat   | byteacat
 byteaeq    | byteaeq
 bytealt    | bytealt
 byteale    | byteale
 byteagt    | byteagt
 byteage    | byteage
 byteane    | byteane
 byteacmp   | byteacmp
 bytealike  | bytealike
 byteanlike | byteanlike
 byteain    | byteain
 byteaout   | byteaout
(12 rows)

SELECT dblink_connect('myconn', 'dbname=regression options=-csearch_path=');
 dblink_connect
----------------
 OK
(1 row)

SELECT * FROM dblink('myconn', 'select proname, prosrc from pg_proc')
  AS t1(proname name, prosrc text) WHERE proname LIKE 'bytea%';
  proname   |   prosrc
------------+------------
 bytearecv  | bytearecv
 byteasend  | byteasend
 byteale    | byteale
 byteagt    | byteagt
 byteage    | byteage
 byteane    | byteane
 byteacmp   | byteacmp
 bytealike  | bytealike
 byteanlike | byteanlike
 byteacat   | byteacat
 byteaeq    | byteaeq
 bytealt    | bytealt
 byteain    | byteain
 byteaout   | byteaout
(14 rows)
</screen>
  </refsect1>
 </refentry>

 <refentry id="contrib-dblink-exec">
  <indexterm>
   <primary>dblink_exec</primary>
  </indexterm>

  <refmeta>
   <refentrytitle>dblink_exec</refentrytitle>
   <manvolnum>3</manvolnum>
  </refmeta>

  <refnamediv>
   <refname>dblink_exec</refname>
   <refpurpose>executes a command in a remote database</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
<synopsis>
dblink_exec(text connname, text sql [, bool fail_on_error]) returns text
dblink_exec(text connstr, text sql [, bool fail_on_error]) returns text
dblink_exec(text sql [, bool fail_on_error]) returns text
</synopsis>
  </refsynopsisdiv>

  <refsect1>
   <title>Description</title>

   <para>
    <function>dblink_exec</function> executes a command (that is, any SQL statement
    that doesn't