Method save_explain_data_intern

sql/sql_select.cc:31620–31802

*/

int JOIN::save_explain_data_intern(Explain_query *output, 
                                   bool need_tmp_table_arg,
                                   bool need_order_arg, bool distinct_arg, 
                                   const char *message)
{
  JOIN *join= this; /* Legacy: this code used to be a non-member function */
  DBUG_ENTER("JOIN::save_explain_data_intern");
  DBUG_PRINT("info", ("Select %p (%u), type %s, message %s",
		      join->select_lex,  join->select_lex->select_number,
                      join->select_lex->type,
		      message ? message : "NULL"));
  DBUG_ASSERT(have_query_plan == QEP_AVAILABLE);
  /* fake_select_lex is created/printed by Explain_union */
  DBUG_ASSERT(join->select_lex != join->unit->fake_select_lex);

  /* There should be no attempts to save query plans for merged selects */
  DBUG_ASSERT(!join->select_lex->master_unit()->derived ||
              join->select_lex->master_unit()->derived->is_materialized_derived() ||
              join->select_lex->master_unit()->derived->is_with_table());

  /* Don't log this into the slow query log */

  if (message)
  {
    if (!(explain= new (output->mem_root)
          Explain_select(output->mem_root,
                         thd->lex->analyze_stmt)))
      DBUG_RETURN(1);
#ifndef DBUG_OFF
    explain->select_lex= select_lex;
#endif
    join->select_lex->set_explain_type(true);

    explain->select_id= join->select_lex->select_number;
    explain->select_type= join->select_lex->type;
    explain->linkage= select_lex->get_linkage();
    explain->using_temporary= need_tmp;
    explain->using_filesort=  need_order_arg;
    /* Setting explain->message means that all other members are invalid */
    explain->message= message;

    if (select_lex->master_unit()->derived)
      explain->connection_type= Explain_node::EXPLAIN_NODE_DERIVED;
    if (save_agg_explain_data(this, explain))
      DBUG_RETURN(1);

    output->add_node(explain);
  }
  else if (pushdown_query)
  {
    if (!(explain= new (output->mem_root)
          Explain_select(output->mem_root,
                         thd->lex->analyze_stmt)))
      DBUG_RETURN(1);
    select_lex->set_explain_type(true);

    explain->select_id=   select_lex->select_number;
    explain->select_type= select_lex->type;