ONGOING MAINTENANCE AND GROWTH - Database Design and Development: An Essential Guide for IT Professionals - page 530

• Have a regular schedule for archiving historical data. Operational systems
usually do not need historical data to be available on-line from the database.
• The greater the number of users in an organization, the greater is the need
for a fully streamlined procedure for security authorizations. The pro-
cedure should ensure strict screening of eligible users, prompt authorizations
wherever needed, and immediate revoking of privileges of terminated

employees.

Application Enhancements

At the time of deployment of the database system, you have initial applications uti-
lizing data from the database. Users access the database through these applications.
Application enhancements include revisions to the initial applications. The revisions
may just be enhancing the GUI screens with additional fields or adding new screens.
Very often, the enhancements take the form of newer phases of the initial applica-
tions. When the database is deployed in an organization for the first time, it is cus-
tomary to bring the users into a database environment with preliminary versions of
the initial applications. Then as the users get more and more accustomed to data-
base concepts, additional versions are implemented.
More involved enhancements relate to brand new applications. For example, the
database may be deployed to serve primarily as a repository for an initial order pro-
cessing application. When this application is pronounced a success, it is quickly fol-
lowed by an inventory control application. After the inventory control application,
another new application may be implemented.
Enhancements have two major requirements. First, application developers
need a development or test database environment for testing the changes. This
environment is separate from the production database environment. The DBA is
responsible for creating and maintaining the test environment. Second, enhance-
ments to the initial applications and development of new applications involve
revisions to the database schema. Depending on the nature of the enhancements or
the new applications, the revisions could be extensive. We will deal with issues
relating to the test environment first. In the next subsection, we will cover schema
revisions.

Test Environment We mentioned creating an entire test or development data-
base environment for the purpose of implementing enhancements to applications.
Why do you need a separate environment? Does this not involve much effort and
resources to have a separate environment operational? Why not accommodate the
testing of revisions in the production database environment itself?
You will find that a separate environment becomes necessary not just for
enhancements. A separate environment is needed even for resolving problems that
arise from time to time. Imagine that an application program that has been in use
for some time aborts suddenly. You need to diagnose the problem, fix it, and have
the user resume processing. The program execution must have tried to go through
one of the paths not taken until now. You need test data with proper conditions to
determine the reason for the problem and resolve it. You cannot add suitable test
data in the production database and corrupt it. You need a separate test database
environment.