Method setup_ref_array

sql/sql_lex.cc:2095–2159

bool st_select_lex::setup_ref_array(THD *thd, uint order_group_num)
{
  // find_order_in_list() may need some extra space, so multiply by two.
  order_group_num*= 2;

  // create_distinct_group() may need some extra space
  const bool select_distinct= MY_TEST(options & SELECT_DISTINCT);
  if (select_distinct)
  {
    uint bitcount= 0;
    Item *item;
    List_iterator<Item> li(item_list);
    while ((item= li++))
    {
      /*
        Same test as in create_distinct_group, when it pushes new items to the
        end of ref_pointer_array. An extra test for 'fixed' which, at this
        stage, will be true only for columns inserted for a '*' wildcard.
      */
      if (item->fixed &&
          item->type() == Item::FIELD_ITEM &&
          item->field_type() == MYSQL_TYPE_BIT)
        ++bitcount;
    }
    order_group_num+= bitcount;
  }

  /*
    We have to create array in prepared statement memory if it is
    prepared statement
  */
  Query_arena *arena= thd->stmt_arena;
  const uint n_elems= (n_sum_items +
                       n_child_sum_items +
                       item_list.elements +
                       select_n_having_items +
                       select_n_where_fields +
                       order_group_num) * 5;
  DBUG_PRINT("info", ("setup_ref_array this %p %4u : %4u %4u %4u %4u %4u %4u",
                      this,
                      n_elems, // :
                      n_sum_items,
                      n_child_sum_items,
                      item_list.elements,
                      select_n_having_items,
                      select_n_where_fields,
                      order_group_num));
  if (!ref_pointer_array.is_null())
  {
    /*
      We need to take 'n_sum_items' into account when allocating the array,
      and this may actually increase during the optimization phase due to
      MIN/MAX rewrite in Item_in_subselect::single_value_transformer.
      In the usual case we can reuse the array from the prepare phase.
      If we need a bigger array, we must allocate a new one.
     */
    if (ref_pointer_array.size() >= n_elems)
      return false;