DB2® Multisystem, a separately priced feature, provides a simple and direct method of distributing a database file over multiple systems in a loosely-coupled environment.
DB2 Multisystem allows users on distributed iSeries™ systems real-time query and update access to a distributed database as if it existed totally on their particular system. DB2 Multisystem places new records on the appropriate system based on a user-defined key field or fields. DB2 Multisystem chooses a system on the basis of either a system-supplied or user-defined hashing algorithm.
Query performance is improved by a factor approaching the number of nodes in the environment. For example, a query against a database distributed over four systems runs in approximately one quarter of the time. However, performance can vary greatly when queries involve joins and grouping. Performance is also influenced by the balance of the data across the multiple nodes. Multisystem runs the query on each system concurrently. DB2 Multisystem can significantly reduce query time on very large databases.