Federated Engine is available as of MySQL 5.0.3. Many environments tend to run MySQL on a single server. Indeed, this is fine for many purposes, but what if you need to aggregate data from a number of different MySQL servers, some of which might reside outside the network or even be owned by another organization altogether? Because it's long been possible to connect to a remote MySQL database server, this doesn't really present a problem; however, the process of managing connections to each separate server can quickly become tedious. To alleviate this problem, you can create a local pointer to remote tables by using the FEDERATED table hander. Doing so allows you to execute queries as if the tables reside locally, saving the hassle of separately connecting to each remote database.
The federated storage engine isnít installed by default, so if it is needed, you will have to configure MySQL with the option --with-federated-storage-engine to take advantage of its features.
Federated Engine Related FAQs