Function execute_sqlcom_select

sql/sql_parse.cc:6123–6248

 }

static bool execute_sqlcom_select(THD *thd, TABLE_LIST *all_tables)
{
  LEX	*lex= thd->lex;
  select_result *result=lex->result;
  bool res;
  /* assign global limit variable if limit is not given */
  {
    SELECT_LEX *param= lex->unit.global_parameters();
    if (!param->limit_params.explicit_limit)
      param->limit_params.select_limit=
        new (thd->mem_root) Item_int(thd,
                                     (ulonglong) thd->variables.select_limit);
  }

  if (!(res= open_and_lock_tables(thd, all_tables, TRUE, 0)))
  {
    lex->resolve_optimizer_hints();
    if (lex->describe)
    {
      /*
        We always use select_send for EXPLAIN, even if it's an EXPLAIN
        for SELECT ... INTO OUTFILE: a user application should be able
        to prepend EXPLAIN to any query and receive output for it,
        even if the query itself redirects the output.
      */
      if (unlikely(!(result= new (thd->mem_root) select_send(thd))))
        return 1;                               /* purecov: inspected */
      thd->send_explain_fields(result, lex->describe, lex->analyze_stmt);
        
      /*
        This will call optimize() for all parts of query. The query plan is
        printed out below.
      */
      res= mysql_explain_union(thd, &lex->unit, result);
      
      /* Print EXPLAIN only if we don't have an error */
      if (likely(!res))
      {
        /* 
          Do like the original select_describe did: remove OFFSET from the
          top-level LIMIT
        */
        result->remove_offset_limit();
        if (lex->explain_json)
        {
          lex->explain->print_explain_json(result, lex->analyze_stmt);
        }
        else
        {
          lex->explain->print_explain(result, thd->lex->describe,
                                      thd->lex->analyze_stmt);
          if (lex->describe & DESCRIBE_EXTENDED)
          {
            char buff[1024];
            String str(buff,(uint32) sizeof(buff), system_charset_info);
            str.length(0);
            /*
              The warnings system requires input in utf8, @see