dblink_fetch — returns rows from an open cursor in a remote database
dblink_fetch(text cursorname, int howmany [, bool fail_on_error]) returns setof record dblink_fetch(text connname, text cursorname, int howmany [, bool fail_on_error]) returns setof record
    dblink_fetch fetches rows from a cursor previously
    established by dblink_open.
   
connnameName of the connection to use; omit this parameter to use the unnamed connection.
cursornameThe name of the cursor to fetch from.
howmany
       The maximum number of rows to retrieve. The next howmany
       rows are fetched, starting at the current cursor position, moving
       forward. Once the cursor has reached its end, no more rows are produced.
      
fail_on_errorIf 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.
    The function returns the row(s) fetched from the cursor.  To use this
    function, you will need to specify the expected set of columns,
    as previously discussed for dblink.
   
    On a mismatch between the number of return columns specified in the
    FROM clause, and the actual number of columns returned by the
    remote cursor, an error will be thrown. In this event, the remote cursor
    is still advanced by as many rows as it would have been if the error had
    not occurred.  The same is true for any other error occurring in the local
    query after the remote FETCH has been done.
   
SELECT dblink_connect('dbname=postgres options=-csearch_path=');
 dblink_connect
----------------
 OK
(1 row)
SELECT dblink_open('foo', 'select proname, prosrc from pg_proc where proname like ''bytea%''');
 dblink_open
-------------
 OK
(1 row)
SELECT * FROM dblink_fetch('foo', 5) AS (funcname name, source text);
 funcname |  source
----------+----------
 byteacat | byteacat
 byteacmp | byteacmp
 byteaeq  | byteaeq
 byteage  | byteage
 byteagt  | byteagt
(5 rows)
SELECT * FROM dblink_fetch('foo', 5) AS (funcname name, source text);
 funcname  |  source
-----------+-----------
 byteain   | byteain
 byteale   | byteale
 bytealike | bytealike
 bytealt   | bytealt
 byteane   | byteane
(5 rows)
SELECT * FROM dblink_fetch('foo', 5) AS (funcname name, source text);
  funcname  |   source
------------+------------
 byteanlike | byteanlike
 byteaout   | byteaout
(2 rows)
SELECT * FROM dblink_fetch('foo', 5) AS (funcname name, source text);
 funcname | source
----------+--------
(0 rows)