Proper way to use query cache

[Francesco Chicchiriccò <il...@apache.org>]

Hi all,
I was used (in Hibernate) to enable query cache on a per-query base by
mean of query hints like as follows:

        Query query = entityManager.createQuery("SELECT e FROM "
                + SchemaMapping.class.getSimpleName() + " e");
        query.setHint("javax.persistence.cache.retrieveMode",
                CacheRetrieveMode.USE);

        return query.getResultList();

Even though I've found this approach not for hibernate only (see [1],
[2] and [3] for example), I've understood that OpenJPA does not support
it (yet?).

Now my question is: provided that I've set

        <shared-cache-mode>ENABLE_SELECTIVE</shared-cache-mode>

and

                <property name="openjpa.DataCache" value="true" />
                <property name="openjpa.QueryCache" value="true" />

in my persistence unit,
how can I activate query cache for a certain query?

TIA.

Regards.

[1] http://en.wikibooks.org/wiki/Java_Persistence/Caching#JPA_2.0_Cache_APIs
[2]
http://wiki.eclipse.org/EclipseLink/Examples/JPA/Caching#How_to_refresh_the_cache
[3] http://www.objectdb.com/java/jpa/persistence/cache

-- 
Francesco Chicchiriccò

Apache Cocoon Committer and PMC Member
http://people.apache.org/~ilgrosso/