System

Instance(s)

Ta

Da

b

tab

ase(s)

Tab 

DB Partition(s)

Tab 

Table space(s)

Ta

ta b

bl  es

index(es)

long data

Figure 1 4   DB2 Objects relationship

Instances

An instance is DB2 code that manages data. It controls what can be done to 

the data, and manages system resources assigned to it. Each instance is a 

complete, fairly independent environment. It contains all the database 

partitions defined for a given parallel database system. An instance has its 

own databases (which other instances cannot access directly), and all its 

database partitions share the same system directories. It also has separate 

security from other instances on the same machine (system), allowing for 

example both production and development environments to be run on the 

same machine under separate DB2 instances without interfering with each 

other. 

Databases

A relational database presents data as a collection of tables. Each database 

includes a set of system catalog tables that describe the logical and physical 

structure of the object in the database, a configuration file containing the 

parameter values configured for the database, and a recovery log. An 

 Chapter 1. Introduction 

11