Getting Started with InfoSphere Data Architect

Chapter 3 – Logical Data Modeling 65
values.
SET_DEFAULT
DO_NOT_ENFORCE
When a parent entity is altered, each nullable foreign key
attribute is set to its default value. This option can only be
specified if all foreign-key attributes have default values.
This generates an informational constraint for DB2 systems.
The code that is generated is not enforced.
An informational referential constraint is a constraint that DB2
does not enforce during normal operations. Use these
constraints only when referential integrity can be enforced
through other means, such as when you retrieve data from
other sources. These constraints might improve performance by
allowing the system to automatically rewrite the query.
Table 3.1 – Definitions for parent and child entity actions
5. Save your work.
3.3 Working with glossary models
Sometimes, when working with various people on the same project, data object naming
varies. Where one data architect might refer to sales entities as SALES_x, another data
modeler might prefer SLS_x. Over time, the system becomes difficult to understand, and
the inconsistency can spread across systems, causing confusion, longer application
development times, or even the inability to make the connection between two fields that
mean the same thing in two different systems.
To avoid this problem, you should develop a set of naming standards early in the data
design process. Naming standards help you and other people in your organization look at
your data in a consistent manner, so that you all get the same meaning. With IBM
InfoSphere Data Architect, you can create a set of rules that all data modelers should
follow, and the workbench can automatically create names of some of the data objects
(such as relationships) for you.
A glossary model is a model that describes the names and abbreviations that an
organization allows for data objects. Data object naming standards promote a common
understanding of data, since you use the same name conventions across the entire
organization. You can use glossary models to enable sharing of data across organizational
boundaries and reduce data redundancy through the consolidation of synonymous and
overlapping data elements.
When you name a data object, you need to take into account two items: semantic rules and
format. Semantically, glossary model objects include prime words, class words, and
modifiers: