Commit f962fa5b authored by sergefp@mysql.com's avatar sergefp@mysql.com
Browse files

Merge spetrunia@bk-internal.mysql.com:/home/bk/mysql-5.0 

into  mysql.com:/home/psergey/mysql-5.0-bug18237-review
parents 85ff7bec be0ebd9e

sql/opt_sum.cc

+7 −20
Original line number Diff line number Diff line
@@ -123,8 +123,11 @@ int opt_sum_query(TABLE_LIST *tables, List<Item> &all_fields,COND *conds) 
      If the storage manager of 'tl' gives exact row count, compute the total

      number of rows. If there are no outer table dependencies, this count

      may be used as the real count.

      Schema tables are filled after this function is invoked, so we can't

      get row count 

    */

    if (tl->table->file->table_flags() & HA_NOT_EXACT_COUNT)

    if ((tl->table->file->table_flags() & HA_NOT_EXACT_COUNT) ||

        tl->schema_table)

    {

      is_exact_count= FALSE;

      count= 1;                                 // ensure count != 0
@@ -149,32 +152,16 @@ int opt_sum_query(TABLE_LIST *tables, List<Item> &all_fields,COND *conds) 
      switch (item_sum->sum_func()) {

      case Item_sum::COUNT_FUNC:

        /*

          If the expr in count(expr) can never be null we can change this

          If the expr in COUNT(expr) can never be null we can change this

          to the number of rows in the tables if this number is exact and

          there are no outer joins.

        */

        if (!conds && !((Item_sum_count*) item)->args[0]->maybe_null &&

            !outer_tables && is_exact_count)

        {

          longlong count= 1;

          TABLE_LIST *table;

          for (table= tables; table; table= table->next_leaf)

          {

            if (outer_tables || (table->table->file->table_flags() &

                                 HA_NOT_EXACT_COUNT) || table->schema_table)

            {

              const_result= 0;			// Can't optimize left join

              break;

            }

            tables->table->file->info(HA_STATUS_VARIABLE | HA_STATUS_NO_LOCK);

            count*= table->table->file->records;

          }

          if (!table)

        {

          ((Item_sum_count*) item)->make_const(count);

          recalc_const_item= 1;

        }

        }

        else

          const_result= 0;

        break;