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Re: [eclipselink-users] EntityManager and historical sessions 
EclipseLink does not currently provide any JPA API for using a historical
session or queries.  There is an enhancement request for this that you can
vote for,

https://bugs.eclipse.org/bugs/show_bug.cgi?id=220807

A historical session is a non-transactional session, so you cannot acquire
it from a UnitOfWork.  The historical session is for querying a past time,
if you haven't committed the data yet, it will not exist in a past time, so
I'm confused as to why you would want to do this?

You can also use an asOf clause in any ReadAllQuery or ReadObjectQuery, and
do not need a historical session to do this.



Magnus Heino wrote:
> 
> Hi.
> 
> I have a HistoryPolicy configured for my entity that is managed by my
> entitymanager.
> 
> I begin a transaction, persist this entity, flush, change it, flush,
> change
> it, flush, and notice that rows are added by the HistoryPolicy to my _HIST
> tables just as expected.
> 
> This is the way I currently aquire my historical session;
> 
> Session historicalSession = this.entityManager.getServerSession()
> 
> .acquireClientSession().acquireHistoricalSession(asOfClause);
> 
> Historical queries are now in a separate database session from the one
> that
> I flushed and added things to above, since that transaction isn't commited
> at this moment.
> 
> Is it possible to have the historical session use the same database
> session
> (or whatever the name for this is) as the current session used by the
> transaction that the entityamanger is using so that I can do historical
> queries on the data that is about to be commited?
> 
> Also, is it possible to use JPA queries to access historical data or do I
> have to use eclipselink apis like ReadAllQuery etc? If not, is this likely
> to change with JPA 2.0 when we will have a standard query api like this?
> 
>  /Magnus Heino
> 


-----
---
http://wiki.eclipse.org/User:James.sutherland.oracle.com James Sutherland 
http://www.eclipse.org/eclipselink/
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