Databases Reference
In-Depth Information
Figure 3-3
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Conceptual Design
Logical Design
Physical Design
Data requirements
Information
requirements
Collection needs
Data locations
Logical framework
Applicable data
Data services
Data modeling
Physical modeling
Database objects
Object placement
Optimization
Physical design.
3.1.2 Determining the Database Type
Early in the modeling process, you need to identify the functional type of data-
base you need. This directly impacts your design requirements. You identify the
functional type by looking at the business and the user application or applica-
tions the database will support.
Databases functionally fall into three general categories:
▲
Transactional
▲
Decision support system (DSS)
▲
Hybrid
This chapter focuses on the transactional database model as its primary exam-
ple, but we must also consider the other models and their core concerns. The
core data modeling concerns are much the same in each of these models.
Designing a Transactional Database
A
transactional database
is designed to support the processing of business
transactions, such as the sales of a product. The primary function of the data-
base is to support the addition of new data and the modification or deletion of
existing data. This is performed at a granular level, typically working in very
small chunks, such as individual records. The database design must be optimized
to support these activities.
The transactional database model is the one used in the vast majority of
database applications. Almost every business you can imagine uses a transac-
tional database as its production database. For example, a retail business needs
to be able to quickly process individual sales and inventory changes. Think about
the checkout lines at the local discount store and it's easy to see why optimiz-
ing these operations is critical. A bank needs to quickly and accurately process
each change to each account, hundreds or thousands of incremental changes
