Question

Background: I’m writing a little desktop application with connection to existing SQL Server DB.

I’m quite familiar with writing SQL queries but this time I want to give JPA a shot. I have my entities mapped and everything is fine, but I’m little worried about perfomance.

I made some profiling and the result is that the JPA code is not really slower than mapping by hands. But there is a still one problem that is bugging me.

I’ve recorded the queries with SQL Server Profiler and Eclipse link is constantly calling exec sp_prepexec and exec sp_unprepare with the same query but diffent parameters.

I’ve rewriten the code to use parameters in query, but still no luck.

The class code is:

In constructor I create EntityManagerFactory and EntityManager

    emf = Persistence.createEntityManagerFactory("ZapytaniaOKonta_1.0");
    em = emf.createEntityManager();
    query=prepareQuery();

In prepareQuery I prepare the query using criteria builder and parameters

    CriteriaBuilder builder = em.getCriteriaBuilder();
    CriteriaQuery<Uczestnik> criteria = builder.createQuery(Uczestnik.class);
    Root<Uczestnik> uczestnikRoot = criteria.from(Uczestnik.class);
    criteria.select(uczestnikRoot);
    ParameterExpression<Boolean> peselFilterParameter = builder.parameter(Boolean.class, "peselFilterParameter");
    ParameterExpression<String> peselParameter = builder.parameter(String.class, "peselParameter");
    Predicate peselPredicate = orBuilder(builder, uczestnikRoot, peselParameter, peselFilterParameter, Uczestnik_.pesel);

    ParameterExpression<Boolean> nipFilterParameter = builder.parameter(Boolean.class, "nipFilterParameter");
    ParameterExpression<String> nipParameter = builder.parameter(String.class, "nipParameter");
    Predicate nipPredicate = orBuilderNip(builder, uczestnikRoot, nipParameter, nipFilterParameter, Uczestnik_.nip);

    ParameterExpression<Boolean> regonFilterParameter = builder.parameter(Boolean.class, "regonFilterParameter");
    ParameterExpression<String> regonParameter = builder.parameter(String.class, "regonParameter");
    Predicate regonPredicate = orBuilder(builder, uczestnikRoot, regonParameter, regonFilterParameter, Uczestnik_.regon);

    criteria.where(builder.and(peselPredicate, nipPredicate, regonPredicate));
    uczestnikPeselRegonNipQuery = em.createQuery(criteria);
    return uczestnikPeselRegonNipQuery;

when using the query I set all the parameters and call

    query.getResultList();

So my question is how can I make EclipseLink or other JPA2 provider use prepared statements?

Answer 1

EclipseLink does not use a statement cache by default. To enable one use,

“eclipselink.jdbc.cache-statements”=”true”

This can only be used with EclipseLink’s connection pooling. When using a JavaEE DataSource, you need to enable statement caching in your JavaEE server’s DataSource config.