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Difference between revisions of "EclipseLink/Examples/JPA/Migration/Hibernate/V3Annotations"
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=== Custom Sequence Generator === | === Custom Sequence Generator === | ||
Revision as of 14:51, 15 July 2008
This example catalogs the migration from Hibernate(TM) Annotations to EclipseLink JPA with its custom annotations. This is a work in progress so please feel free to add your comment
Contents
Entity Annotations
@org.hibernate.annotations.Entity
@org.hibernate.annotations.Entity( selectBeforeUpdate = true, dynamicInsert = true, dynamicUpdate = true, optimisticLock = OptimisticLockType.ALL, polymorphism = PolymorphismType.EXPLICIT)
Optimistic Locking
EclipseLink's optimistic locking functionality supports all of the Hibernate locking types and more. This table translated the locking types from Hibernate's @Entity(optimisticLock) attributes into the EclipseLink locking policies which can be configured with @OptimisticLocking or in EclipseLink's ORM.XML.
| Hibernate's OptimisticLockType | Description | EclipseLink OptimisticLocking |
|---|---|---|
| NONE | no optimistic locking | EclipseLink defaults to no optimistic locking |
| VERSION | use a column version | JPA @Version
or EclipseLink @OptimisticLocking(type = OptimisticLockingType.VERSION_COLUMN) |
| DIRTY | dirty columns are compared | JPA @Version or EclipseLink @OptimisticLocking(type = OptimisticLockingType.CHANGED_COLUMNS) |
| ALL | all columns are compared | @OptimisticLocking(type = OptimisticLockingType.ALL_COLUMNS) |
Additionally EclipseLink provides support for comparing a specific set of selected columns using OptimisticLockingType.SELECTED_COLUMNS. This approach allows you to select the critical columns that should be compared if the CHANGED or ALL strategies do not meet your needs.
Custom Sequence Generator
In Hibernate a custom generator for sequence values can be defined and used as:
@Id @GeneratedValue(generator = "system-uuid") @GenericGenerator(name = "system-uuid", strategy = "mypackage.UUIDGenerator") public String getTransactionGuid()
With EclipseLink a custom sequence generator can be implemented and registered for use using the @GeneratedValue. See: How to use Custom Sequencing (ie. UUID) for more details.