connstr, text sql [, bool fail_on_error]) returns setof record
dblink(text sql [, bool fail_on_error]) returns setof record
</synopsis>
  </refsynopsisdiv>

  <refsect1>
   <title>Description</title>

   <para>
    <function>dblink</function> executes a query (usually a <command>SELECT</command>,
    but it can be any SQL statement that returns rows) in a remote database.
   </para>

   <para>
    When two <type>text</type> arguments are given, the first one is first
    looked up as a persistent connection's name; if found, the command
    is executed on that connection.  If not found, the first argument
    is treated as a connection info string as for <function>dblink_connect</function>,
    and the indicated connection is made just for the duration of this command.
   </para>
  </refsect1>

  <refsect1>
   <title>Arguments</title>

   <variablelist>
    <varlistentry>
     <term><parameter>connname</parameter></term>
     <listitem>
      <para>
       Name of the connection to use; omit this parameter to use the
       unnamed connection.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><parameter>connstr</parameter></term>
     <listitem>
      <para>
       A connection info string, as previously described for
       <function>dblink_connect</function>.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><parameter>sql</parameter></term>
     <listitem>
      <para>
       The SQL query that you wish to execute in the remote database,
       for example <literal>select * from foo</literal>.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><parameter>fail_on_error</parameter></term>
     <listitem>
      <para>
       If true (the default when omitted) then an error thrown on the
       remote side of the connection causes an error to also be thrown
       locally. If false, the remote error is locally reported as a NOTICE,
       and the function returns no rows.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </refsect1>

  <refsect1>
   <title>Return Value</title>

   <para>
    The function returns the row(s) produced by the query.  Since
    <function>dblink</function> can be used with any query, it is declared
    to return <type>record</type>, rather than specifying any particular
    set of columns.  This means that you must specify the expected
    set of columns in the calling query &mdash; otherwise
    <productname>PostgreSQL</productname> would not know what to expect.
    Here is an example:

<programlisting>
SELECT *
    FROM dblink('dbname=mydb options=-csearch_path=',
                'select proname, prosrc from pg_proc')
      AS t1(proname name, prosrc text)
    WHERE proname LIKE 'bytea%';
</programlisting>

    The <quote>alias</quote> part of the <literal>FROM</literal> clause must
    specify the column names and types that the function will return.
    (Specifying column names in an alias is actually 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