ONGOING MAINTENANCE AND GROWTH - Database Design and Development: An Essential Guide for IT Professionals - page 534

• Install new version in production and perform a dry run
• Run selected programs and queries in production before turning over new
version for use

TUNING FOR PERFORMANCE

During the design and implementation phases, all the facts and statistics are not
available. The designers and developers go by the information obtained while gath-
ering requirements. As users begin to use the database after deployment, new usage
patterns emerge. Over time, usage patterns change. Also, the size of the database
increases. Ongoing tuning for performance becomes an essential activity.
In a database environment, problems and bottlenecks affect the performance at
four levels: (1) the hardware level, primarily the data storage devices, (2) the level
of the operating system that enables the actual interface with the storage devices,
(3) the level of the DBMS that manages the database, and (4) the level of the appli-
cations that execute transactions and queries. Therefore, any effort at tuning must
include considerations at all these four levels. The DBA coordinates the tuning
activity, taking primary responsibility for tuning the DBMS. The technical support
personnel perform the tuning of the operating system and deal with hardware
configurations. Applications staff such as programmers and analysts get involved
in applications tuning.
Figure 17-6 illustrates the nature of tuning the database environment at differ-
ent levels.
Tuning the database environment involves looking at various aspects of perfor-
mance. The following is just a sample of the factors to be considered while tuning
for performance:

• Database configuration parameters
• Disk block utilization parameters
• Memory buffer pools

Tuning Level s

Appli-
cations

Systems Analyst

Users

DBMS

Pgmr/Analyst

Operating
System

DBA

Technical Support

Hardware

Systems Programmer

Figure 17-6 Tuning the database environment.