This tutorial uses as it's basis a MySQL replication system in the simplest configuration possible. The reader should be familiar with the implementation and management of such a configuration. All of the databases in the replication group must be configured to allow incoming connections from the machine running as the PHP client.
The MySQL replication system provides an easily to implement alternative to true clustering, but is limited in the fact that it allows only a single read-write node in it's configuration. Updates are spawned almost simultaneously to all other nodes. If the goal of the configuration is to delegate server load by running resource-intensive, expensive queries to a secondary machine, this can be achieved simply using the ADOdb Load Balancer (ADB).