Re: [eclipselink-users] Savepoints, Checkpoints, Rollbacks?

[James Sutherland <jamesssss@xxxxxxxxx>]

I suppose it would be nice if it were in both specifications.  But until that
day, it may be possible to provide a flush() like API in EclipseLink.

Feel free to request the spec extension with Sun or the JCP as well.



saasira wrote:
> 
> Hi,
>       excuse me if what I say doesn't make sense!
> 
> Isn't the save points a feature that should go into JTA rather than JPA,
> of
> course JPA should provide a facility to use the the save points provided
> by
> JTA.
> 
> Regards,
> Samba
> 
> On Tue, Feb 17, 2009 at 8:42 PM, James Sutherland
> <jamesssss@xxxxxxxxx>wrote:
> 
>>
>> There are no savepoints in JPA.  Please log this enhancement request in
>> EclipseLink.
>>
>> The native EclipseLink API has something similar called nested
>> UnitOfWork,
>> but these are entirely in-memory nested transactions.  Nested UnitOfWork
>> support has currently not been exposed in the EclipseLink JPA API.
>>
>> With your code the main thing to be careful of is ensuring the
>> consistency
>> of your object changes and database (the database will get rolled back,
>> but
>> your objects will remain the same).  Clear will clear out all the
>> objects,
>> so may be ok.  You also need to consider the shared cache, but by default
>> a
>> flush() followed by a clear() will invalidate the changed objects, so
>> should
>> be ok.
>>
>>
>>
>> paulccarey wrote:
>> >
>> > OK so it doesn't look like this is possible directly with JPA or
>> > Eclipselink as far as I can tell however I've managed to coble this
>> > together, in case its of any use to anyone hear goes....
>> >
>> > first to get a savepoint...
>> >
>> > EntityManager em;
>> > ...
>> >
>> >     public Savepoint getSavepoint() throws SQLException {
>> >         em.flush();
>> >         //Get the SQL connection
>> >         Connection conn = ((UnitOfWorkImpl) ((JpaEntityManager)
>> >
>> em).getActiveSession().acquireUnitOfWork()).getAccessor().getConnection();
>> >
>> >         //Get a savepoint from the SQL connection
>> >         return conn.setSavepoint();
>> >
>> >     }
>> >
>> > next to make use of it...
>> >     public void commitToSave1(Savepoint sp) throws SQLException {
>> >         Connection conn = ((UnitOfWorkImpl) ((JpaEntityManager)
>> >
>> em).getActiveSession().acquireUnitOfWork()).getAccessor().getConnection();
>> >         //roll the connection back to the savepoint
>> >         conn.rollback(sp);
>> >         //commit the current state of the transaction
>> >         conn.commit();
>> >         //clear the persistence context causing all managed entities to
>> >         //become detached
>> >         em.clear();
>> >         //commit the transaction to release locks and reset the entity
>> >         //manager
>> >         em.getTransaction().commit();
>> >     }
>> >
>> > Hope that may be of use to someone:-D
>> >
>> >
>> >
>> > paulccarey wrote:
>> >>
>> >> Hi I am using eclipselink with JPA
>> >>
>> >> Is it possible to create savepoints like JDBC can?
>> >>
>> >> So I can rollback a transaction to a certain point without losing all
>> >> changes?
>> >>
>> >> Thanks
>> >>
>> >> P
>> >>
>> >
>> >
> 
> 


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