Re: Hibernate mapping for sql join
On 12.03.2011 15:51, Arved Sandstrom wrote:
OK, I see where you're coming from a bit more clearly. For background,
JPA is the standard Java EE persistence API, and it describes/defines
JPQL - the Java Persistence Query Language. Think of JPA as an ORM
abstraction that persistence providers like Hibernate and
Toplink/EclipseLink support. Hibernate and EclipseLink still retain
their own native ORM APIs.
JPQL is actually a subset of HQL as of Hibernate 3, and in any case has
always looked like HQL a lot.
Now, if you're using Hibernate, but _not_ the JPA layer supported by
Hibernate (since it is a JPA provider as well), that's cool. I'm no
expert on Hibernate, and in fact when I use EclipseLink I don't use the
native APIs unless there's a really good reason to. So I don't know all
the nooks and crannies of the Hibernate native APIs. But one possibility
is using native SQL in your Hibernate queries and applying a result
transformer. This is similar to iBatis result maps as near as I can tell.
As a side note, I'm guessing Hibernate Session here means a client (as
opposed to server) session, in which case *if* you were using JPA - and
I'm not saying you should - a Session would back up a JPA EntityManager.
In the scenario here what Peter probably wants is a stateless session,
because the result set seems to be large and you don't want all those
instances to go to the cache:
http://docs.jboss.org/hibernate/core/3.6/reference/en-US/html/batch.html#batch-statelesssession
Of course one loses a lot of Hibernate's functionality that way but two
aspects (SQL abstraction, ORM) are still there.
I am not 100% sure whether JPA provides a similar mechanism, but
constructor expression does indeed look similar.
Kind regards
robert
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