Geographic Information Systems: An Introduction, 3rd Edition

12.5 Database Design

To solve typical tasks efficiently, GIS databases have to be designed in an appropriate way. Normally, database design comprises three main elements:

1. Conceptual design is hardware and software independent and specifies the end user's needs. Usually, conceptual design includes the same elements as those included in data structuring/data modeling.
2. Logical design is software dependent but hardware independent and sets out the logical structure of the database elements determined by the different GIS software.
3. Physical design is hardware dependent and includes file structure, memory and disk space, access, and speed, among other attributes.

Conceptual and logical design are described in the following section, and physical design is discussed further in Chapter 18.

12.5.1 Conceptual database design

Even though good DBMSs have been developed for GIS, the usefulness of any system will be no better than the data entered into the database. To be useful, data must be organized. Disorganized data in DBMS are unproductive; in other words, garbage in, garbage out. For example, if the intention is to show all water pipes in a network that are 10 cm in diameter, the result will be of doubtful value if the pipe data are entered sometimes as inside diameters and at other times as outside diameters. A transport analysis can be performed only if elements of the road network—its bridges, tunnels, and ferry routes—are entered as secondary parts of the primary network, not as ...