Oracle Database Architectures
Oracle Tips by Burleson Consulting
High Performance Data Warehousing
Database Architectures For The 1990s
In this manner, aggregate datatypes can be
defined and addressed in a table definition just like any other
relational datatype. In the following example, we see the phone_nbr
and address datatypes being used in a table definition:
create table CUSTOMER (
Here, we see that a single data field in a table may be a range of
values or an entire table. This concept is called complex, or
unstructured, data typing (see Figure 1.11). The domain of values
for a specific field in a relational database may be defined with
this approach. This ability to nest data tables allows for
relationship data to be incorporated directly into the table
structure. For example, the occupations field in the table
establishes a one-to-many relationship between an employee and his
or her valid occupations. Also, note the ability to nest the entire
SKILLS table within a single field. In this example, only valid
skills may reside in the skills field, and this implements the
relational concept of domain integrity.
Figure 1.11 An example of abstract datatypes (ADTs).
DEFINITION OF AGGREGATE OBJECTS
In Oracle8, aggregate objects can be defined and preassembled for
fast retrieval. For example, a report_card may be defined for a
university database. The report_card object may be defined such that
it is assembled at runtime from its atomic components (similar to an
Oracle view), or the report_card may be preassembled and stored in
the database. These aggregate objects may have methods (such as
stored procedures) attached to them, such that an Oracle object
couples data and behavior together.
This is an excerpt from "High Performance
Data Warehousing", copyright 1997.
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