PHYSICAL ELEMENTS OF DATA MODELS - A Developer's Guide to Data Modeling for SQL Server - page 79

Supertypes and Subtypes: A Final Word
Implementing supertypes and subtypes can, at times, be tricky. If you take
the time to fully understand the data and look at the implications of split-
ting the data into multiple tables versus keeping it tighter, you should be
able to determine the best course of action. Don't be afraid to generate
some test data and run various options through performance tests to make
sure you make the correct choice. When we get to building the physical
model, we look at using subtype clusters as well as other alternatives for es-
pecially complex situations.
Summary
In this chapter, we have looked at the available objects inside SQL Server
that you will use when implementing your physical model. It's important to
understand these objects for many reasons. You must keep all this in mind
when you design your logical model so that you design with SQL Server in
mind. This also plays a large part later when you build and implement your
physical model. You will probably not use every object in SQL Server for
every database you build, but you need to know your options. Later, we
walk through creating your physical model, and at that time we go over the
various ways you can use these physical objects to solve problems.
In the next chapter, we talk about normalization, and then we move on
to the meat and potatoes of this topic by getting into our sample project
and digging into a lot of real-world issues.