On Mon, 13 Oct 2008, Mikkel H�gh wrote:
> Well, in that benchmark, what you say is only true for the Niagara
> processors. On the Opteron page, MySQL performance only drops slightly as
> concurrency passes 50.
That's partly because the upper limit on the graph only goes to 100
concurrent processes. Since the Opterons are faster, that's not a broad
enough scale to see how fast the right edge of the MySQL curve falls.
You are right that the Niagara processors have a sharper decline than the
more traditional platforms. The MySQL 5.0.20a graphs at
http://tweakers.net/reviews/657/6 has a nice comparison graph showing a
few different architectures that's also interesting.
Anyway, you don't actually have to believe any of this; you've got a
testbed to try for yourself if you just crank the user count up. The main
thing I was trying to suggest is that MySQL being a bit faster at 5 users
is not unusual, but it's not really representative of which performs
better either.
> In general, MySQL seems to have problems with some kinds of threading,
> since their perfomance on Mac OS X is crappy as well for that reason.
One of the reasons (but by no means not the only one) that PostgreSQL uses
a multi-process based architecture instead of a threaded one is because
thread library quality varies so much between platforms.
--
* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD