26.10.2014 Views

z/VSE: 45 Years of Progress - z/VM - IBM

z/VSE: 45 Years of Progress - z/VM - IBM

z/VSE: 45 Years of Progress - z/VM - IBM

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

How DB2 for<br />

z/OS Application<br />

Requirements Affect<br />

Database Design<br />

For most DBAs, the question, “Do application requirements<br />

affect the database design?” has an obvious<br />

answer: Of course!<br />

Regrettably, important things are forgotten or ignored during<br />

data modeling and database design. This article discusses<br />

common post-implementation issues that can be avoided by<br />

giving them proper consideration during the design process.<br />

By Lockwood Lyon<br />

Database Design Practices<br />

Database design flows from business rules, application<br />

requirements, and your data modeling standards such as normalization<br />

and referential integrity enforcement.<br />

What about a set <strong>of</strong> tables implemented to augment a current<br />

batch system? These will probably be fully normalized per<br />

current database design standards. Is this a new database in an<br />

enterprise data warehouse? Most likely, the design will include<br />

fact, dimension, and key tables with star join access paths. Will<br />

this new data support a mission-critical application with tens<br />

<strong>of</strong> thousands <strong>of</strong> users? Perhaps there will be some denormalization<br />

<strong>of</strong> the design for performance reasons.<br />

DBAs tend to design databases based primarily on functionality<br />

and performance. Will the database support the business<br />

rules <strong>of</strong> the application? Will it perform based on the Service-<br />

Level Agreement (SLA)?<br />

This prioritization is backward. There are just as many, if not<br />

more, important issues that should be addressed during database<br />

design. Factors such as recoverability and data availability<br />

are either missed or given lower priority.<br />

After implementation, when recovery and availability issues ><br />

z / J o u r n a l • O c t o b e r / N o v e m b e r 2 0 1 0 • 3 1

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!