How To Configure Query Cacheing in EclipseLink

Question

I have a collection of states, that I want to cache for the life of the application, preferably after it is called for the first time. I'm using EclipseLink as my persistence provider. In my EJB3 entity I have the following code:

@Cache
@NamedQueries({
    @NamedQuery(
        name = "State.findAll",
        query = "SELECT s FROM State s",
        hints = {
                @QueryHint(name=QueryHints.CACHE_USAGE, value=CacheUsage.CheckCacheThenDatabase),
                @QueryHint(name=QueryHints.READ_ONLY, value=HintValues.TRUE)
            }
    )
})

This doesn't seem to do anything though, if I monitor the SQL queries going to MySQL it still does a select each time my Session Bean uses this NamedQuery.

What is the correct way to configure this query so that it is only ever read once from the database, preferably across all sessions?

Edit: I am calling the query like this:

Query query = em.createNamedQuery("State.findAll");
List<State> states = query.getResultList();

Viridissa

Best of luck figuring out the session/caching configuration of EclipseLink. I never could. – Winne

QueryHints.CACHE_USAGE with CacheUsage.CheckCacheThenDatabase caused my list query to return only one entry. Works correctly with @André Luiz Cardoso's answer. – Haun

Answer 1

The solutions posted here not worked for me. But i've made it work with:

@Cache
@NamedQueries({@NamedQuery(
      name = "State.findAll",
      query = "SELECT s FROM State s", 
      hints = {
          @QueryHint(name = QueryHints.QUERY_RESULTS_CACHE, value = HintValues.TRUE)
      }
    )})

Goofball

Exactly, QueryHints.CACHE_USAGE is for the use of second level cache. If you want query cache the hint you have to use is, as Andre said: QueryHints.QUERY_RESULTS_CACHE – Stretchy

The @Cache annotation is not required for query to work with cache – Sanborne

Answer 2

Just a guess here, but you might try

query.cacheQueryResults();

after you create it but before you getResultList.

-- MarkusQ

Annal

Can you elaborate on how this would work? The JPA Query object does not support the cacheQueryResults() method. If I instead create a ReadObjectQuery I don't know how (or if I can) ask it for a list? – Viridissa

If you don't want to use the eclipselink especific query, you have to use hints. It can be done through annotations, as Andre explained or through query.setHint(QueryHints.QUERY_RESULTS_CACHE, HintValues.TRUE) – Stretchy

Answer 3

I got EclipseLink 1.0.1 cache to work by adding just the query hint:

Query query = em.createNamedQuery("Person.find");
query.setParameter("NAME", name);      
query.setHint("eclipselink.cache-usage", "CheckCacheThenDatabase");
return (Person)query.getSingleResult();

I didn't change the entity at all, and haven't yet tried to configure cache using annotations.

Euphony

For single result eclipselink.cache-usage with CheckCacheThenDatabase seem to be needed. But for result list it caused the query to return only one item. – Haun