Commit acaa584c authored by dlenev@mockturtle.local's avatar dlenev@mockturtle.local
Browse files

Fix for bug#22338 "Valgrind warning: uninitialized variable in 

create_tmp_table()".

The fix for bug 21787 "COUNT(*) + ORDER BY + LIMIT returns wrong
result" introduced valgrind warnings which occured during execution
of information_schema.test and sp-prelocking.test in version 5.0.
There were no user visible effects.

The latter fix made create_tmp_table() dependant on
THD::lex::current_select value. Valgrind warnings occured when this
function was executed and THD::lex::current_select member pointed
to uninitialized SELECT_LEX instance.

This fix tries to remove this dependancy by moving some logic
outside of create_tmp_table() function.
parent 7897f061

sql/sql_select.cc

+24 −19
Original line number Diff line number Diff line
@@ -932,17 +932,28 @@ JOIN::optimize() 


    tmp_table_param.hidden_field_count= (all_fields.elements -

					 fields_list.elements);

    ORDER *tmp_group= ((!simple_group && !procedure &&

                        !(test_flags & TEST_NO_KEY_GROUP)) ? group_list :

                                                             (ORDER*) 0);

    /*

      Pushing LIMIT to the temporary table creation is not applicable

      when there is ORDER BY or GROUP BY or there is no GROUP BY, but

      there are aggregate functions, because in all these cases we need

      all result rows.

    */

    ha_rows tmp_rows_limit= ((order == 0 || skip_sort_order ||

                              test(select_options & OPTION_BUFFER_RESULT)) &&

                             !tmp_group &&

                             !thd->lex->current_select->with_sum_func) ?

                            select_limit : HA_POS_ERROR;



    if (!(exec_tmp_table1 =

	  create_tmp_table(thd, &tmp_table_param, all_fields,

			   ((!simple_group && !procedure &&

			     !(test_flags & TEST_NO_KEY_GROUP)) ?

			    group_list : (ORDER*) 0),

                           tmp_group,

			   group_list ? 0 : select_distinct,

			   group_list && simple_group,

			   select_options,

			   (order == 0 || skip_sort_order || 

                            test(select_options & OPTION_BUFFER_RESULT)) ? 

                             select_limit : HA_POS_ERROR,

                           tmp_rows_limit,

			   (char *) "")))

      DBUG_RETURN(1);
@@ -5566,6 +5577,13 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields, 
			  thd->variables.max_heap_table_size) :

		      thd->variables.tmp_table_size)/ table->reclength);

  set_if_bigger(table->max_rows,1);		// For dummy start options

  /*

    Push the LIMIT clause to the temporary table creation, so that we

    materialize only up to 'rows_limit' records instead of all result records.

  */

  set_if_smaller(table->max_rows, rows_limit);

  param->end_write_records= rows_limit;



  keyinfo=param->keyinfo;



  if (group)
@@ -5686,19 +5704,6 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields, 
    }

  }



  /*

    Push the LIMIT clause to the temporary table creation, so that we

    materialize only up to 'rows_limit' records instead of all result records.

    This optimization is not applicable when there is GROUP BY or there is

    no GROUP BY, but there are aggregate functions, because both must be

    computed for all result rows.

  */

  if (!group && !thd->lex->current_select->with_sum_func)

  {

    set_if_smaller(table->max_rows, rows_limit);

    param->end_write_records= rows_limit;

  }



  if (thd->is_fatal_error)				// If end of memory

    goto err;					 /* purecov: inspected */

  table->db_record_offset=1;