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, let’s move on to discuss the basics of decision support systems and expert systems.

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This is an excerpt from "High Performance Data Warehousing", copyright 1997.

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