I don't think the problem is the database as such, but if you are relying on a framework which doesn't really have any business layer, you are kind of screwed. So I think that Twitters problem is rather the lack of a business layer, resulting in db overuse, rather than having routing decisions in the db. That can be a good way to go, as long as there is some intelligent handling of the routing itself, as you describe in your previous entry.
Hi, I was actually going to
Hi,
I was actually going to write a rather overbearing comment on this entry, but then I read another one of your entries http://www.appistry.com/blogs/bob/biz/how-make-twitter-scalable which I totally (well mostly) agree with.
I don't think the problem is the database as such, but if you are relying on a framework which doesn't really have any business layer, you are kind of screwed. So I think that Twitters problem is rather the lack of a business layer, resulting in db overuse, rather than having routing decisions in the db. That can be a good way to go, as long as there is some intelligent handling of the routing itself, as you describe in your previous entry.