I've been following Tim O'Reilly's series on how large sites scale their databases. Also, this article about topix.net. They seem to fall into two camps:
Amazingly, Craig's List uses MyISAM tables. I guess it's nearly all reads, but I just didn't think the locking approach used for MyISAM tables would hold up to traffic like that. A primary reason why I use InnoDB is the row-level locking and the multi-version concurrency system, which means that readers don't block writers.
Two interesting things here are that none of them use PostgreSQL, despite a few of them being fairly new, and that none of them have tried commercial offerings for database clustering, like the stuff IMB and Oracle sell.
In fact, I've never met anyone who had tried the Oracle or DB2 clustering. Even the people who have the money seem to avoid it. Can anyone offer any personal anecdotes about it? Does it work at all?