Adding DMS containers

You can increase the size of a DMS table space (that is, one created with the MANAGED BY DATABASE clause) by adding one or more containers to the table space.

About this task

No rebalancing occurs if you are adding new containers and creating a new stripe set. A new stripe set is created using the BEGIN NEW STRIPE SET clause on the ALTER TABLESPACE statement. You can also add containers to existing stripe sets using the ADD TO STRIPE SET clause on the ALTER TABLESPACE statement.

The addition or modification of DMS containers (both file and raw device containers) is performed in parallel through prefetchers. To achieve an increase in parallelism of these create or resize container operations, you can increase the number of prefetchers running in the system. The only process which is not done in parallel is the logging of these actions and, in the case of creating containers, the tagging of the containers.

Note: To maximize the parallelism of the CREATE TABLESPACE or ALTER TABLESPACE statements (with respect to adding new containers to an existing table space) ensure that the number of prefetchers is greater than or equal to the number of containers being added. The number of prefetchers is controlled by the num_ioservers database configuration parameter. The database must be stopped for the new parameter value to take effect. In other words, all applications and users must disconnect from the database for the change to take effect.

Important: The DMS table space type is deprecated for user-defined permanent table spaces and might be removed in a future release. The DMS table space type is not deprecated for catalog and temporary table spaces. For more information, see DMS permanent table spaces have been deprecated.

Example

The following example illustrates how to add two new device containers (each with 10 000 pages) to a table space on a Linux® or UNIX operating system:

    ALTER TABLESPACE RESOURCE
      ADD (DEVICE '/dev/rhd9'  10000,
           DEVICE  '/dev/rhd10' 10000)

Note that the ALTER TABLESPACE statement allows you to change other properties of the table space that can affect performance.