Internet database system

1. Field of the Invention An incrementally-scalable database system and method. The system architecture enables database servers to be scaled by adding resources, such as additional servers, without requiring that the system be taken offline. Such scaling includes both adding one or more computer servers to a given server cluster, which enables an increase in database read transaction throughput, and adding one or more server clusters to the system configuration, which provides for increased read and write transaction throughput. The system also provides for load balancing read transactions across each server cluster, and load balancing write transactions across a plurality of server clusters. The system architecture includes an application server layer including one or more computers on which an application program(s) is running, a database server layer comprising two or more server clusters that each include two or more computer servers with replicated data, and an intermediate "virtual transaction" layer that includes at least two computers that facilitate database transactions with one or more databases operating in the database server layer. Data in the database(s) are evenly distributed across the server clusters in fragmented mutually exclusive subsets of data based on a hashing function. An application program interface is provided so as to enable application programs to perform a full range of database transactions without regard for where data is stored, or what database(s) is operating in the database server layer.