Example Product 2
To achieve the high levels of performance required by the largest Web sites, a multitier system typically balances the processing load for each tier across multiple servers. Microsoft® SQL Server™ 2000 shares the database processing load across a group of servers by horizontally partitioning the SQL Server data. These servers are managed independently, but cooperate to process the database requests from the applications; such a cooperative group of servers is called a federation.
A federated database tier can achieve extremely high levels of performance only if the application sends each SQL statement to the member server that has most of the data required by the statement. This is called collocating the SQL statement with the data required by the statement. Collocating SQL statements with the required data is not a requirement unique to federated servers.I It is also required in clustered systems.
Although a federation of servers presents the same image to the applications as a single database server, there are internal differences in how the database services tier is implemented.