Simple solution to the 'twitter' scaling problem

You couldn't do this, because you would get ID conflicts from
auto-increment. Two inserts on the same table on each DB would
conflict.

However, there are facilities for multi-master replication in some
databases, such as Mysql 5 [1] You need to have some sort of code to
handle connections, at least to watch for dead servers and failover.
Also, you'd want to designate some read-only servers pretty early on
because writing across many masters would get expensive quickly. So
then you are back to square one, as need to handle writing to certain
databases and reading from others. Nic's plugin would handle that, I
believe.

In other words, scaling can start simple but it gets complicated quick :).

1 - http://www.onlamp.com/pub/a/onlamp/2006/04/20/advanced-mysql-replication.html

- Rob