DB2 extends the database manager to the parallel, multi-node environment. A database partition is a part of a database that consists of its own data, indexes, configuration files, and transaction logs. A database partition is sometimes called a node or a database node. (Node was the term used in the DB2 Parallel Edition for AIX Version 1 product.)
A single-partition database is a database having only one database partition. All data in the database is stored in that partition. In this case nodegroups (see Nodegroups), while present, provide no additional capability.
A partitioned database is a database with two or more database partitions. Tables can be located in one or more database partitions. When a table is in a nodegroup consisting of multiple partitions, some of its rows are stored in one partition, and other rows are stored in other partitions.
Usually, a single database partition exists on each physical node, and the processors on each system are used by the database manager at each database partition to manage its part of the total data in the database.
Because data is divided across database partitions, you can use the power of multiple processors on multiple physical nodes to satisfy requests for information. Data retrieval and update requests are decomposed automatically into sub-requests, and executed in parallel among the applicable database partitions. The fact that databases are split across database partitions is transparent to users issuing SQL statements.
User interaction occurs through one database partition, known as the coordinator node for that user. The coordinator runs on the same database partition as the application, or in the case of a remote application, the database partition to which that application is connected. Any database partition can be used as a coordinator node.