Method initialize_tables

sql/sql_delete.cc:1256–1367

}

bool
multi_delete::initialize_tables(JOIN *join)
{
  TABLE_LIST *walk;
  DBUG_ENTER("initialize_tables");

  if (unlikely((thd->variables.option_bits & OPTION_SAFE_UPDATES) &&
               error_if_full_join(join)))
    DBUG_RETURN(1);
  main_table=join->join_tab->table;

  table_map tables_to_delete_from= 0;
  delete_while_scanning= true;
  for (walk= delete_tables; walk; walk= walk->next_local)
  {
    TABLE_LIST *tbl= walk->correspondent_table->find_table_for_update();
    tables_to_delete_from|= tbl->table->map;

    /*
      Ensure that filesort re-reads the row from the engine before
      delete is called.
    */
    join->map2table[tbl->table->tablenr]->keep_current_rowid= true;

    if (delete_while_scanning &&
        unique_table(thd, tbl, join->tables_list, 0))
    {
      /*
        If the table we are going to delete from appears
        in join, we need to defer delete. So the delete
        doesn't interfere with the scanning of results.
      */
      delete_while_scanning= false;
    }
  }

  walk= delete_tables;
  uint index= 0;
  for (JOIN_TAB *tab= first_linear_tab(join, WITHOUT_BUSH_ROOTS,
                                       WITH_CONST_TABLES);
       tab;
       tab= next_linear_tab(join, tab, WITHOUT_BUSH_ROOTS))
  {
    if (!tab->bush_children && tab->table->map & tables_to_delete_from)
    {
      /* We are going to delete from this table */
      TABLE *tbl=walk->table=tab->table;
      TABLE_LIST *prior= walk;
      walk= walk->next_local;
      /* Don't use KEYREAD optimization on this table */
      tbl->no_keyread=1;
      /* Don't use record cache */
      tbl->no_cache= 1;
      tbl->covering_keys.clear_all();
      if (tbl->file->has_transactions())
	transactional_tables= 1;
      else
	normal_tables= 1;