Working with Descriptors

A TopLink descriptor stores all the information describing how an instance of a particular class can be represented in a relational database. Although you may need to amend a descriptor (for example, to specify a property not supported by TopLink), do not modify any descriptors after registering them with the session.

TopLink descriptors contain the following information:

The persistent Java class it describes and the corresponding database table(s) for storing instances of that class
A collection of mappings, which describe how the attributes and relationships for that class are stored in the database
The primary key information of the table(s)
A list of query keys (or aliases) for field names
Information for sequence numbers
A set of optional properties for tailoring the behavior of the descriptor, including support for identity maps, optimistic locking, the Event Manager, and the Query Manager
Caching refresh options