again, on benchmarks

Dear interweb, if you have no idea what you’re writing about, keep it to yourself, don’t litter into the tubes. Some people may not notice they’re eating absolute crap and get diarrhea.

This particular benchmark has two favorite parts, that go with each other together really well:

I didnt change absolutely any parameters for the servers, eg didn’t change the innodb_buffer_pool_size or key_buffer_size.

And..

If you need speed just to fetch a data for a given combination or key, Redis is a solution that you need to look at. MySQL can no way compare to Redis and Memcache. …

Seriously, how does one repay for all the damage of such idiotic benchmarks?

P.S. I’ve ranted at benchmarks before, and will continue doing so.

On file system benchmarks

I see this benchmark being quoted in multiple places, and there I see stuff like:

When carrying out more database benchmarking, but this time with PostgreSQL, XFS and Btrfs were too slow to even complete this test, even when it had been running for more than an hour for a single run. Between EXT3, EXT4, and NILFS2, the fastest file-system was EXT3 and then its successor, EXT4, was slightly behind that. Far behind the position of EXT4 were NILFS2 and then Btrfs and XFS.

There were few other benchmarks, e.g. SQLite showed ‘bad performance’ on XFS and Btrfs.

*clear throat*

Dear benchmarkers, don’t compare apples and oranges. If you see differences between benchmarks, do some very very tiny research, and use some intellect, that you, as primates, do have. If database tests are slowest on filesystems created by Oracle (who know some stuff about systems in general) or SGI (who, despite giving away their campus to Google, still have lots of expertise in the field), that can indicate, that your tests are probably flawed somewhere, at least for that test domain.

Now, probably you’ve heard about such thing as ‘data consistency’. That is something what database stack tries to ensure, sometimes at higher costs, like not trusting volatile caches, enforcing certain write orders, depending on acknowledgements by underlying hardware.

So, in this case it wasn’t “benchmarking file systems”, it was simply, benchmarking “consistency” against “no consistency”. But don’t worry, most benchmarks have such flaws – getting numbers but not understanding them makes results much more interesting, right?

Oh, and… thanks for few more misguided people.