Databases

A DB2® database is a relational database. The database stores all data in tables that are related to one another. Relationships are established between tables such that data is shared and duplication is minimized.

A relational database is a database that is treated as a set of tables and manipulated in accordance with the relational model of data. It contains a set of objects used to store, manage, and access data. Examples of such objects are tables, views, indexes, functions, triggers, and packages. Objects can be either defined by the system (built-in objects) or defined by the user (user-defined objects).

A distributed relational database consists of a set of tables and other objects that are spread across different but interconnected computer systems. Each computer system has a relational database manager to manage the tables in its environment. The database managers communicate and cooperate with each other in a way that allows a given database manager to execute SQL statements on another computer system.

A partitioned relational database is a relational database whose data is managed across multiple database partitions. This separation of data across database partitions is transparent to most SQL statements. However, some data definition language (DDL) statements take database partition information into consideration (for example, CREATE DATABASE PARTITION GROUP). DDL is the subset of SQL statements used to describe data relationships in a database.

A federated database is a relational database whose data is stored in multiple data sources (such as separate relational databases). The data appears as if it were all in a single large database and can be accessed through traditional SQL queries. Changes to the data can be explicitly directed to the appropriate data source.