Hibernate has a Stateless Version of its Session: Does something similar exist for the JPA EntityManager? I.e. an EntityManager that does not use the first level cache?
Is there a stateless version of the JPA EntityManager?
7.2k views Asked by Jens Schauder AtThere are 3 answers
From JPA point of view:
javax.persistence.EntityManager
stands for 1st level cache (persistence context, transactional cache)javax.persistence.EntityManagerFactory
stands for 2nd level cache (shared cache)
A given persistence provider may implement additional caching layers. Additionally JDBC Driver API may be treated as low-level cache for storing columns/tables and caching connections/statements. It's however transparent to JPA.
Both javax.persistence.EntityManager and org.hibernate.StatelessSession offer similar APIs.
You cannot disable 1st level cache with EntityManager beacuse these two things are equivalent. You can however:
- skip 1st level cache by using
createQuery
,createNamedQuery
,createNativeQuery
for querying and bulk updates/deletes (the persistence context is not updated to reflect their results). Such queries should be executed in their own transaction thus invalidating any cached entities, if any. Transaction-scoped entity manager (means stateless) should be used as well. - disable 2nd level cache by setting up
<shared-cache-mode>NONE</shared-cache-mode>
in persistence.xml orjavax.persistence.sharedCache.mode
in properties
On an interface point of view, RDBMS usually respect the ACID constraints, a stateless option would be very specific. I guess this is the reason why Hibernate proposes this feature but not the specification.
To disable the cache, you have implementation-specific configurations (here is the doc for EclipseLink). The @Cacheable annotation (JPA 2.0) at the entity level is standard.
But if you would like to perform bulk operations, this would not do the job. Anyway, such a behavior would be implementation-specific.
Not part of the JPA API or spec. Individual implementations may allow disabling the L1 cache. DataNucleus JPA, the one I have used, does allow this