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
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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 />
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