bool Explain_join::explain_key_and_len()

{

  if (tab->ref.key_parts)

    return explain_key_and_len_index(tab->ref.key, tab->ref.key_length,

                                     tab->ref.key_parts);

  else if (tab->type == JT_INDEX_SCAN)

    return explain_key_and_len_index(tab->index);

  else if (select && select->quick)

    return explain_key_and_len_quick(select);

  else

  {

    const TABLE_LIST *table_list= table->pos_in_table_list;

    if (table_list->schema_table &&

        table_list->schema_table->i_s_requested_object & OPTIMIZE_I_S_TABLE)

    {

      StringBuffer<> str_key(cs);

      const char *f_name;

      int f_idx;

      if (table_list->has_db_lookup_value)

      {

        f_idx= table_list->schema_table->idx_field1;

        f_name= table_list->schema_table->fields_info[f_idx].field_name;

        str_key.append(f_name, strlen(f_name), cs);

      }

      if (table_list->has_table_lookup_value)

      {

        if (table_list->has_db_lookup_value)

          str_key.append(',');

        f_idx= table_list->schema_table->idx_field2;

        f_name= table_list->schema_table->fields_info[f_idx].field_name;

        str_key.append(f_name, strlen(f_name), cs);

      }

      if (str_key.length())

        return fmt->entry()->col_key.set(str_key);

    }

  }

  return false;

}