Method init

sql/sql_expression_cache.cc:95–179

*/

void Expression_cache_tmptable::init()
{
  List_iterator<Item> li(items);
  Item_iterator_list it(li);
  uint field_counter;
  LEX_CSTRING cache_table_name= { STRING_WITH_LEN("subquery-cache-table") };
  DBUG_ENTER("Expression_cache_tmptable::init");
  DBUG_ASSERT(!inited);
  inited= TRUE;
  cache_table= NULL;

  if (items.elements == 0)
  {
    DBUG_PRINT("info", ("All parameters were removed by optimizer."));
    DBUG_VOID_RETURN;
  }

  /* add result field */
  items.push_front(val);

  cache_table_param.init();
  /* dependent items and result */
  cache_table_param.field_count= cache_table_param.func_count= items.elements;
  /* postpone table creation to index description */
  cache_table_param.skip_create_table= 1;

  if (!(cache_table= create_tmp_table(table_thd, &cache_table_param,
                                      items, (ORDER*) NULL,
                                      FALSE, TRUE,
                                      ((table_thd->variables.option_bits |
                                        TMP_TABLE_ALL_COLUMNS) &
                                        ~TMP_TABLE_FORCE_MYISAM),
                                      HA_POS_ERROR,
                                      &cache_table_name,
                                      TRUE)))
  {
    DBUG_PRINT("error", ("create_tmp_table failed, caching switched off"));
    DBUG_VOID_RETURN;
  }

  if (cache_table->s->db_type() != heap_hton)
  {
    DBUG_PRINT("error", ("we need only heap table"));
    goto error;
  }

  field_counter= 1;

  if (cache_table->alloc_keys(1) ||
      cache_table->add_tmp_key(0, items.elements - 1, &field_enumerator,
                                (uchar*)&field_counter, TRUE) ||
      ref.tmp_table_index_lookup_init(table_thd, cache_table->key_info, it,
                                      TRUE, 1 /* skip result field*/))
  {
    DBUG_PRINT("error", ("creating index failed"));
    goto error;
  }
  cache_table->s->keys= 1;