169 words

javax.persistence.Version - JPA annotation

javax.persistence
Annotation Version

Target:
Fields (including property get methods)
Specifies the version field or property of an entity class that serves as its optimistic lock value. The version is used to ensure integrity when performing the merge operation and for optimistic concurrency control.

Only a single Version property or field should be used per class; applications that use more than one Version property or field will not be portable.

The Version property should be mapped to the primary table for the entity class; applications that map the Version property to a table other than the primary table will not be portable.

The following types are supported for version properties: int, Integer, short, Short, long, Long, java.sql.Timestamp.

Example:

    @Version
    @Column(name="OPTLOCK")
    protected int getVersionNum() { return versionNum; }

Since:
JPA 1.0
Learn how to define and use version fields in Chapter 2 of the ObjectDB/JPA manual.
This annotation is a marker annotation (with no elements).

This documentation page is derived (with some adjustments) from the open source JPA 2 RI (EclipseLink)
and is available under the terms of the Eclipse Public License, v. 1.0 and Eclipse Distribution License, v. 1.0.
Object Relational Mapping (ORM) JPA 2 providers include Hibernate, EclipseLink, TopLink, OpenJPA and DataNucleus.
Object DB is not an ORM JPA implementation but an Object Database for Java with built in JPA 2 support.