Converting the Data and Storing It in an Object Database
If you are in a situation where it makes more sense to convert the relational data to the object schema, then the equivalent views discussed earlier will again be of use. Each of these equivalent views has a corresponding relational view. See checking the class hierarchy.
The relational view can be used to access the data in the relational database. The conversion process, however, will only use the relational views that correspond with the classes at the bottom of the class hierarchy, the leaf classes described earlier. The converted data will be stored in these leaf classes. The classes in the object schema hierarchy above the leaf classes provide alternate ways to view or classify the data that is the equivalent to other views that existed in the relational schema.
To create a conversion program, use the single-valued views (the ones that use only one type code) to get the data from the relational database and populate object instances for the appropriate leaf class in the object schema managed by the Object DBMS (ODBMS). The upside of doing this is that you get the integration and performance provided by the ODBMS. The downside is that you will either convert the existing applications to access the ODBMS through an ODBC or JDBC interface or develop new applications. Many ODBMS products provide ODBC and JDBC interfaces. This allows the object data to appear as relational data, using the view equivalents that were presented earlier.
Next: Leaving the data in the relational database and using an object database. Also see the related content below.
More on the general topic: Using the Data
- Leaving the Data in the Relational Database
- Leaving the Data in a Relational Database and Using an Object Database