If there is a heavy load on the site then two databases are better than one.

You can always "slave" one database to the other so that all updates to the "master" database get automatically replicated into the other.

Mind you, this means that the second ("slave") database cannot be updated directly: all updates must be made to the first ("master") database, to be replicated through the replication system.

CountZero

"If you have four groups working on a compiler, you'll get a 4-pass compiler." - Conway's Law