Function join_read_last_key

sql/sql_select.cc:25526–25573

*/
  
static int
join_read_last_key(JOIN_TAB *tab)
{
  int error;
  TABLE *table= tab->table;

  if (!table->file->inited &&
      unlikely((error= table->file->ha_index_init(tab->ref.key, tab->sorted))))
  {
    (void) report_error(table, error);
    return 1;
  }

  if (unlikely(cp_buffer_from_ref(tab->join->thd, table, &tab->ref)))
    return -1;
  if (unlikely((error=
                table->file->prepare_index_key_scan_map(tab->ref.key_buff,
                                                        make_prev_keypart_map(tab->ref.key_parts)))) )
  {
    report_error(table,error);
    return -1;
  }

  /*
    Tell the storage engine what the range endpoint is so that it can stop
    scanning once it has hit that point.
   */
  key_range range_endpoint
  {
    tab->ref.key_buff,
    tab->ref.key_length,
    make_prev_keypart_map(tab->ref.key_parts),
    HA_READ_PREFIX_LAST
  };
  table->file->set_end_range(&range_endpoint, handler::RANGE_SCAN_DESC);

  if (unlikely((error=
                table->file->ha_index_read_map(table->record[0],
                                               tab->ref.key_buff,
                                               make_prev_keypart_map(tab->ref.key_parts),
                                               HA_READ_PREFIX_LAST))))
  {
    if (error != HA_ERR_KEY_NOT_FOUND && error != HA_ERR_END_OF_FILE)
      return report_error(table, error);
    return -1; /* purecov: inspected */
  }
  return 0;
}


	/* ARGSUSED */