Hibernate 2nd level cache invalidation when another process modifies the database

Question

We have an application that uses Hibernate\'s 2nd level caching to avoid database hits.

I was wondering if there is some easy way to invalidate the Java application

Answer 1

Both hibernate and JPA now provide direct access to the underlying 2nd level cache:

sessionFactory.getCache().evict(..);
entityManager.getCache().evict(..)

Answer 2

I was searching how to invalidate all Hibernate caches and I found this useful snippet:

sessionFactory.getCache().evictQueryRegions();
sessionFactory.getCache().evictDefaultQueryRegion();
sessionFactory.getCache().evictCollectionRegions();
sessionFactory.getCache().evictEntityRegions();

Hope it helps to someone else.

Answer 3

You may try doing this:

private EntityManager em;

public void clear2ndLevelHibernateCache() {
    Session s = (Session) em.getDelegate();
    SessionFactory sf = s.getSessionFactory();

    sf.getCache().evictQueryRegions();
    sf.getCache().evictDefaultQueryRegion();
    sf.getCache().evictCollectionRegions();
    sf.getCache().evictEntityRegions();

    return;
}

I hope It helps.

Answer 4

SessionFactory has plenty of evict() methods precisely for that purpose:

sessionFactory.evict(MyEntity.class); // remove all MyEntity instances
sessionFactory.evict(MyEntity.class, new Long(1)); // remove a particular MyEntity instances

Answer 5

One thing to take into account when using distributed cache is that QueryCache is local, and evicting it on one node, does not evicts it from other. Another issue is - evicting Entity region without evicting Query region will cause N+1 selects,when trying to retrieve date from Query cache. Good readings on this topic here.

Answer 6

Based on ChssPly76's comments here's a method that evicts all entities from 2nd level cache (we can expose this method to admins through JMX or other admin tools):

/**
 * Evicts all second level cache hibernate entites. This is generally only
 * needed when an external application modifies the game databaase.
 */
public void evict2ndLevelCache() {
    try {
        Map<String, ClassMetadata> classesMetadata = sessionFactory.getAllClassMetadata();
        for (String entityName : classesMetadata.keySet()) {
            logger.info("Evicting Entity from 2nd level cache: " + entityName);
            sessionFactory.evictEntity(entityName);
        }
    } catch (Exception e) {
        logger.logp(Level.SEVERE, "SessionController", "evict2ndLevelCache", "Error evicting 2nd level hibernate cache entities: ", e);
    }
}