Correct. Blaine Cook blogged (in the post this article riffs from) that they don't use ActiveRecord, for example.
I believe someone has made the defensible claim that most of their activity occurs via clients (twhirl, alert thingy) and SMS over the API rather than through the website. Unless they are using ActionController and ActionView to do the rendering and output there, it seems they would be using "traditional RoR" in a very limited capacity.
I'm not being an apologist, but I think if people are discussing Twitter and scaling for the purposes of learning something useful and not just framework bashing, language bashing or avoiding doing homework, we should probably avoiding talking as if they use the full stack in a significant way as it's a red herring.
Well said - I remember reading somewhere before that the database was mentioned (as usual) as the problem area.
Someone else in the comments mentioned 400K messages a day, plus personal messages, say thats even another 400K.
I have zero experience working on a high traffic web application, but I work on a serious database application were we can push somewhere in the region of 1M transactions in a 6-8 hour window. Each of these transactions comes in the form of an XML string and results in as many as 20 plus selects and maybe 10 - 20 inserts.
Our application is build on top of Oracle and implemented in PLSQL - not too sexy, but it seems to get the job done.
The point I am trying to make is that with a bit of a caching layer it takes some serious throughput to reach the limits of database scalability (certainly with Oracle, where is where my experience lies).
I believe someone has made the defensible claim that most of their activity occurs via clients (twhirl, alert thingy) and SMS over the API rather than through the website. Unless they are using ActionController and ActionView to do the rendering and output there, it seems they would be using "traditional RoR" in a very limited capacity.
I'm not being an apologist, but I think if people are discussing Twitter and scaling for the purposes of learning something useful and not just framework bashing, language bashing or avoiding doing homework, we should probably avoiding talking as if they use the full stack in a significant way as it's a red herring.