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Re: tmp-table-tests MariaDB 5.2.6 vs. 5.5.12 vs. 5.1.57


Hi, erkan!

On May 30, erkan yanar wrote:
> Moin, 
> I did some tmp-table tests. As it is told MariaDB is faster on
> tmp-tables because of the Aria-Engine.

I've tried that, but without mysqlslap. Your table structure, few times more rows,
mysql-5.1, mariadb-5.2 with aria tmp tables, mariadb-5.2 with myisam tmp
tables. I didn't try mysql-5.5. I used a query like

  SELECT id, tea from t1 group by left(id,1) order by null;

where "group by left(id,1)" makes sure the number of groups is small
(only ten), so the result set is small and the query doesn't spend most
of its time sending thousands of result rows. And "order by null"
removes filesort from the query plan.

I've got almost identical numbers (which is a bit scary, considering
different setup, and different queries).

MariaDB with myisam tmp tables performed similar to MySQL (1.2-1.5 sec)
MariaDB with aria tables was slower (5.1-5.7 sec).

I remember that few months ago Monty fixed a slowdown caused by Aria
temp tables. May be this fix didn't get into 5.2? Or you've found a
different problem? I'll let Monty comment on it - he was already
debugging this problem once.


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