Databases Reference
In-Depth Information
The DBA is also responsible for database design, testing, and performance tuning.
The DBA establishes a sound methodology for database design, such as the one discussed in Chapter 6, and
ensures that all database designers follow the methodology. The DBA also verifies that the designers obtain all
pertinent information from the appropriate users. After the database designers complete the information-
level design, the DBA does the physical-level design.
The DBA establishes documentation standards for all the steps in the database design process. The DBA
also makes sure that these standards are followed, that the documentation is kept up to date, and that the
appropriate personnel have access to the documentation they need.
Requirements don't remain stable over time; they change constantly. The DBA reviews all changes to
requirements and determines whether the changes will require that modifications be made to the database. If
so, the DBA makes the changes in the design and in the data in the database. The DBA also verifies that pro-
grammers modify all programs and documentation affected by the change.
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The hardware, software, and database for the users is called the
production system
,or
live system
. The DBA
strictly controls the production system. With just two exceptions, the DBA grants access and update privi-
leges to the production system only to authorized users. The first exception is when problems occur, such as
with software. The DBA and others must troubleshoot the problem by accessing the production system. The
second exception is when programmers complete new programs or modify existing programs for the produc-
tion system. For both exceptions, the DBA performs any necessary database modifications or closely con-
trols the activities of others.
Other than for these two exceptions, the DBA does not grant programmers access to the production system.
Instead, the DBA and the programmers create a separate system, called the
test system
,or
sandbox
, that pro-
grammers use to develop new programs and modify existing programs. After programmers complete the test-
ing of their programs in the test system, a separate quality assurance group performs futher tests, the DBA and
the users review and approve the test results, and the DBA reviews and approves the programs and
documentation. If the DBA and the users approve, the DBA notifies all affected users when new or corrected fea-
tures will be available. The DBA then transfers the programs to the production system and makes any required
database changes, as shown in Figure 8-9.
