ODMG Object-Oriented Data Warehouse
Oracle Tips by Burleson Consulting
High Performance Data Warehousing
Database Architectures For The 1990s
The IS-A Construct
While the object-oriented data model as defined by ODMG appears to
be more rigid than the relational data model, it still has some
compelling features for data warehousing. The main drawback to
object-oriented databases is their use of embedded pointers to
establish data relationships. This means that new relationships
cannot be easily added to a data warehouse model. In an
object-oriented database, when a new relationship is added, each
object in the database must be visited and restructured to make room
for the new pointer that establishes the new relationship. Once the
objects have restructured to make room for the pointer, a program
must be written to add the physical pointers to the pointer fields.
This is a very complex and time-consuming operation. In short, the
object-oriented data model requires much more careful up-front
analysis to ensure that all of the data relationships have been
identified before the database schema is compiled.
On the positive side, object-oriented databases have some very
useful features for data warehousing. The ability to tightly couple
data with behavior makes it very easy to locate warehouse queries.
In addition, we can also quickly overload existing behaviors to
create new methods. Finally, encapsulation helps ensure that changes
to methods only affect their target object type--we never see any
unintended side effects from code changes.
Now that we have reviewed the basic database architectures, we
should address some of the issues that will arise when extracting
data for Oracle warehouses. Remember, many of the data sources for
your Oracle warehouse will come from non-relational database
architectures, and the savvy warehouse designer must understand how
data extraction will function.
To understand the types of applications that Oracle warehouses will
be expected to support, letís move on to discuss the basics of
decision support systems and expert systems.
This is an excerpt from "High Performance
Data Warehousing", copyright 1997.
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