Method init_derived

sql/table.cc:10159–10291

*/

bool TABLE_LIST::init_derived(THD *thd, bool init_view)
{
  SELECT_LEX *first_select= get_single_select();
  SELECT_LEX_UNIT *unit= get_unit();

  if (!unit)
    return FALSE;
  /*
    Check whether we can merge this derived table into main select.
    Depending on the result field translation will or will not
    be created.
  */
  TABLE_LIST *first_table= (TABLE_LIST *) first_select->table_list.first;
  if (first_select->table_list.elements > 1 ||
      (first_table && first_table->is_multitable()))
    set_multitable();

  if (!unit->derived)
    unit->derived= this;
  else if (!is_with_table_recursive_reference() && unit->derived != this)
  {
    if (unit->derived->is_with_table_recursive_reference())
      unit->derived= this;
    else if (vers_conditions.eq(unit->derived->vers_conditions))
      vers_conditions.empty();
    else
    {
      my_error(ER_CONFLICTING_FOR_SYSTEM_TIME, MYF(0));
      return TRUE;
    }
  }

  if (init_view && !view &&
      !derived_table_optimization_done(this))
  {
    /* This is all what we can do for a derived table for now. */
    set_derived();
  }

  if (!derived_table_optimization_done(this))
  {
    /* A subquery might be forced to be materialized due to a side-effect. */
    bool forced_no_merge_for_update_delete=
           belong_to_view ? belong_to_view->updating :
                           !unit->outer_select()->outer_select();

    if (with && updating)
    {
      /*
        We are trying to update or delete from a CTE. This is not allowed.
        Don't merge it, then the check for update of non-updatable table
        will catch this and report an error.
      */
      set_materialized_derived();
    }

    /*
       In the case where a table merge operation moves a derived table from