Solving Operational Business Intelligence with InfoSphere Warehouse Advanced Edition

300 Solving Operational Business Intelligence with InfoSphere Warehouse Advanced Edition

minimum number of times. Optim High Performance Unload uses system

resources but does not require you to connect to the production database.

Data can be restored by using the LOAD command with an INSERT with

SELECT statement. Alternatively, the ALTER TABLE DETACH and ATTACH

command can be used to switch the recovered data partition with the

corrupted data partition. These operations do not take the system offline as is

required when using the RESTORE command.

򐂰 The recovery process has to take place away from the production system.

When data must be restored and validated outside of the production system,

you can unload data for dropped or corrupted tables into a non-production

system. This action allows you to cleanse and prepare data for load into the

production system. Use this approach to minimize the effect on the

production system.

When used in this way, Optim High Performance Unload must be installed on

the non-production system and a copy of the database catalog backup image

must be accessible. If only a single column has been compromised, use

Optim High Performance Unload to unload only the primary key and the

contents of the affected column.

8.4.3 Optim High Performance Unload in a production environment

Optim High Performance Unload is designed to unload data at fast speeds and

all available system resources are consumed in achieving this. It is important that

you configure Optim High Performance Unload to use the resources that you

want Optim High Performance Unload to use. There are two principle methods of

controlling the resources used by Optim High Performance Unload:

򐂰 Control parallelism with the MAXSELECTS parameter.

The MAXSELECTS parameter determines the number of SELECT

statements and therefore the number of tables to be processed in parallel

when unloading data from backup images. This minimizes the number of

times the backup image is read but increases the resources required by the

Optim High Performance Unload process.

If a value for MAXSELECTS is not specified, Optim High Performance Unload

attempts to process all SELECT statements in the unload block, or all tables

in a specified table space.

We recommend that you include a MAXSELECTS entry in the Optim High

Performance Unload configuration file, db2hpu.cfg, and associate a

value of 1 with the entry. This action prevents an Optim High Performance

Unload process from consuming more resources than intended. Use the

MAXSELECTS control file configuration parameter to restrict the number of