Distributed databases

An SQL query can require information from multiple tables. When tables are distributed, the tables can be physically located in separate databases. To access data from distributed tables, the query is split into multiple queries, with one query for each database. To service each query, the application virtual machine activates multiple database drivers. One active database driver is called upon to retrieve the data required from a single database. When all of the data the original query requires is gathered from the databases, the database driver joins the data and returns the data to the application virtual machine.