SPI_scroll_cursor_move — move a cursor
void SPI_scroll_cursor_move(Portalportal, FetchDirectiondirection, longcount)
   SPI_scroll_cursor_move skips over some number of rows
   in a cursor.  This is equivalent to the SQL command
   MOVE.
  
Portal portalportal containing the cursor
FetchDirection direction
      one of FETCH_FORWARD,
      FETCH_BACKWARD,
      FETCH_ABSOLUTE or
      FETCH_RELATIVE
     
long count
      number of rows to move for
      FETCH_FORWARD or
      FETCH_BACKWARD; absolute row number to move to for
      FETCH_ABSOLUTE; or relative row number to move to for
      FETCH_RELATIVE
     
   SPI_processed is set as in
   SPI_execute if successful.
   SPI_tuptable is set to NULL, since
   no rows are returned by this function.
  
   See the SQL FETCH command
   for details of the interpretation of the
   direction and
   count parameters.
  
   Direction values other than FETCH_FORWARD
   may fail if the cursor's plan was not created
   with the CURSOR_OPT_SCROLL option.