Re: Benchmark Query 4x Faster on MySQL 5.5
I've got similar difference on my machine on the latest releases (all release tarball packages):

MariaDB 5.5.24: ~25 sec
MariaDB 5.3.7: ~25 sec
MariaDB 5.2.12: ~8 sec
MySQL 5.5.25: ~8 sec
MySQL 5.6.5: ~20 sec

Re: Benchmark Query 4x Faster on MySQL 5.5
Was there a real-life workload that goes much slower with MariaDB 5.5 or was this merely out-of-curiosity type of question?

If this is out-of-curiousity, the explanation is this:

MariaDB implemented microseconds precision for temporal datatypes. In the past, internal representation of temporal datatypes was 64 bit integer. Now, it is decimal. Decimals are slower than integers in many scenarios .

Now, there are still some optimizations to speed up datetimes and avoid decimals in different scenarios. For example, FROM_UNIXTIME understands that its parameter is integer and does not do decimal arithmetic in this case. In your example, FROM_UNIXTIME gets a double parameter and thus needs to be converted into decimal.

Thus, you can speed up your query by roughly 50%, if you rewrite it as

BENCHMARK(10000000,DATE_SUB(FROM_UNIXTIME(FLOOR(RAND() * 2147483648)), INTERVAL (FLOOR(1 + RAND() * 365)) DAY))

Note the FROM_UNIXTIME(FLOOR(...)), FLOOR was not there in original query.

Re: Benchmark Query 4x Faster on MySQL 5.5
It wasn't purely out-of-curiosity. It was to confirm the overall performance that MariaDB has vs MySQL. I'm new to MariaDB and not a DB engineer or even a full time DBA.

With your new query forcing a integer result from RAND it is still much slower than MySQL but is faster overall.

Results for new query from my workstation:

• MariaDB 5.3.3 - 15.00 secs
• MySQL 5.5.17 4.04 secs

I would think as a general rule that any query would run at least the same speed if not faster. Even with the FLOOR RAND it it still slower by a significant amount.

Launchpad bug id: 1008334