There are many reasons for splitting a database.
For example, suppose that a company maintains an organizational database that contains several international subsidiaries in several time zones. Each subsidiary relies on time-sensitive financial calculations. You can split the database for groups of subsidiaries in the same time zone to ensure that financial calculations are timely.
You can also use a partitioned application to separate information by subsidiary.
Essbase - Suppression of interdimensional irrelevance by splitting the database