Oracle9i added SQL type inheritance to
the database, as well as object view hierarchies, type evolution, generic and transient
datatypes, function-based indexes for type method functions, and multilevel
Figure 14-1. Purchase order class hierarchy
Internal Purchase Order External Purchase Order
Purchase Order
Purchase Order
Contracted Supplier
Purchase Order
Noncontracted Supplier
322 | Chapter 14: Oracle Extended Datatypes
collections. Oracle Database 10g added support for remote access to object types.
Oracle Database 11g added an ANSI SQL feature that provides a method invocation
scoping operator.
Other extensibility features
Several other extensibility features are included in the Objects and Extensibility features.
These include:
??? The ability to create new index types by defining the structure of the index
??? The ability to store the index data inside or outside the Oracle database
??? The ability to create user-defined operators for use in standard SQL statements
??? An interface to the cost-based optimizer to extend support for user-defined
object types and indexes
The use of object-relational features is most common today among software developers
who are building database extensions.
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