Learning Visually with Examples [Electronic resources] نسخه متنی

7.3. Partition Groups

A database

partition group is a set of one or more database partitions. By grouping database partitions, you can perform database operations at the partition group level rather than individually on each partition. This allows for database administration flexibility. For example, let's say you want to create a buffer pool with the same definition in three partitions. If you first create a partition group

pgall that consists of the three partitions, you can associate the buffer pool

bp1 you are about to create with this partition group. This lets you use the same buffer pool definition on each partition.

Partition groups also allow you to associate table spaces to database partitions. For example, if you would like table space

tbls1 to use only database partitions 1 and 2, you can create a partition group

pg12 with these two partitions, and then associate the table space

tbls1 to

pg12.

Figure 7.7 illustrates the objects discussed in the preceding examples.

In Chapter 8, The DB2 Storage Model, for more details.

When you create a database, three partition groups are created by default.

• IBMCATGROUP is the partition group where the DB2 catalog table space (SYSCATSPACE) resides. It consists of only one partition, the one where the

  CREATE DATABASE command is issued.

• IBMTEMPGROUP is the partition group where the system temporary table space (TEMPSPACE1) resides. It spans all partitions.

• IBMDEFAULTGROUP is the partition group where the user table space (USERSPACE1) resides. It spans all partitions.

These default partition groups are discussed in detail in Chapter 8, The DB2 Storage Model.