27 Configuring an Object-Relational Descriptor

This chapter describes the various components that you must configure to be able to use an object-relational descriptor.

For more information, see the following:

Table 27-1 lists the configurable options for a relational descriptor.

Object-Relational Descriptor Configuration Overview

Table 27-1 lists the configurable options for an object-relational descriptor.

Table 27-1 Configurable Options for Object-Relational Descriptor

Option	Type	TopLink Workbench	Java
"Configuring Field Ordering"	Basic
"Configuring Primary Keys"	Basic
"Configuring Read-Only Descriptors"	Advanced
"Configuring Unit of Work Conforming at the Descriptor Level"	Advanced
"Configuring Query Keys"	Advanced
"Configuring Cache Expiration at the Descriptor Level"	Advanced
"Configuring Amendment Methods"	Advanced
"Configuring Reading Subclasses on Queries"	Advanced
"Configuring Inheritance for a Child (Branch or Leaf) Class Descriptor"	Advanced
"Configuring Inheritance for a Parent (Root) Descriptor"	Advanced
"Configuring Inheritance Expressions for a Parent (Root) Class Descriptor"	Advanced
"Configuring Inherited Attribute Mapping in a Subclass"	Advanced
"Configuring Cache Type and Size at the Descriptor Level"	Advanced
"Configuring a Domain Object Method as an Event Handler"	Advanced
"Configuring a Descriptor Event Listener as an Event Handler"	Advanced
"Configuring Locking Policy"	Advanced
"Configuring Copy Policy"	Advanced
"Configuring Instantiation Policy"	Advanced
"Configuring Wrapper Policy"	Advanced
"Configuring a History Policy"	Advanced
"Configuring Returning Policy"	Advanced

Configuring Field Ordering

If your object-relational data source driver uses JDBC indexed arrays, you can specify the order in which TopLink persists object attributes to define the field index.

Using Java

Use ObjectRelationalDescriptor method addFieldOrdering to specify the field ordering. Example 27-1 shows how to specify the order of the object-relational database fields OBJECT_ID, F_NAME, and L_NAME for the Employee descriptor.

Example 27-1 Field Ordering

descriptor.addFieldOrdering("ID");
descriptor.addFieldOrdering("F_NAME");
descriptor.addFieldOrdering("L_NAME");