Alright, thank you for looking into it. I will use a List of Entities that contain the key and value and see if performance is better.
Henno -----Oorspronkelijk bericht----- Van: Rick Curtis [mailto:[email protected]] Verzonden: donderdag 17 februari 2011 17:27 Aan: [email protected] Onderwerp: Re: N+1 select problem for Map no matter what I try Heno - It looks like this is the expected behavior. Keep an eye on OPENJPA-1920 for any changes that we may try to make in this area. Thanks, Rick On Thu, Feb 17, 2011 at 8:37 AM, Henno Vermeulen <[email protected]>wrote: > That's great, thank you for your time! > > Heno > > -----Oorspronkelijk bericht----- > Van: Rick Curtis [mailto:[email protected]] > Verzonden: donderdag 17 februari 2011 15:36 > Aan: [email protected] > Onderwerp: Re: N+1 select problem for Map no matter what I try > > Ok, now I was able to recreate the behavior that you reported... I'll dig > into this a little more and get back with you. > > Thanks, > Rick > > On Thu, Feb 17, 2011 at 4:25 AM, Henno Vermeulen <[email protected] > >wrote: > > > Thank you for your reply! I tried and it unfortunately doesn't work. I > > stripped my example down to the bare minimum. I am using OpenJPA 2.0.0 > > (downloaded openjpa-all using Maven). > > In my real application I use compile time enhancement and mssql server, I > > am running this test with hsqldb and openjpa as javaagent > > > (-javaagent:C:/Users/h.vermeulen/.m2/repository/org/apache/openjpa/openjpa-all/2.0.0/openjpa-all-2.0.0.jar). > > > > Here are my classes and settings: > > > > Persistence.xml: > > <persistence xmlns="http://java.sun.com/xml/ns/persistence"; > > xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"; > > xsi:schemaLocation=" > http://java.sun.com/xml/ns/persistencepersistence_1_0.xsd"; > > version="1.0"> > > > > <persistence-unit name="testPU"> > > > > <provider>org.apache.openjpa.persistence.PersistenceProviderImpl > > </provider> > > <class>entities.TestEntity</class> > > <exclude-unlisted-classes>true</exclude-unlisted-classes> > > <properties> > > <property name="openjpa.jdbc.SynchronizeMappings" > > value="buildSchema" /> > > <property name="openjpa.ConnectionDriverName" > > value="org.hsqldb.jdbcDriver" /> > > <property name="openjpa.ConnectionURL" > > value="jdbc:hsqldb:mem:test" /> > > <property name="openjpa.ConnectionUserName" > > value="sa" /> > > <property name="openjpa.ConnectionPassword" > value="" > > /> > > <property name="openjpa.Log" > > value="DefaultLevel=TRACE" /> > > </properties> > > </persistence-unit> > > </persistence> > > > > TestEntity.java: > > package entities; > > > > import java.util.HashMap; > > import java.util.Map; > > > > import javax.persistence.CascadeType; > > import javax.persistence.Entity; > > import javax.persistence.FetchType; > > import javax.persistence.GeneratedValue; > > import javax.persistence.Id; > > > > import org.apache.openjpa.persistence.PersistentMap; > > > > @Entity > > public class TestEntity { > > > > @Id > > @GeneratedValue > > private Long id; > > > > @PersistentMap(elementCascade = CascadeType.PERSIST, fetch = > > FetchType.EAGER) > > private Map<String, String> strings = new HashMap<String, > > String>(); > > > > public TestEntity() { > > } > > > > public Long getId() { > > return id; > > } > > > > public Map<String, String> getStrings() { > > return strings; > > } > > > > } > > > > MapPerformanceTest.java: > > import java.util.List; > > > > import javax.persistence.EntityManagerFactory; > > import javax.persistence.Persistence; > > > > import org.apache.openjpa.persistence.OpenJPAEntityManager; > > > > import entities.TestEntity; > > > > public class MapPerformanceTest { > > private EntityManagerFactory factory; > > > > public void createEntityManagerFactory() { > > factory = Persistence.createEntityManagerFactory("testPU", > > System > > .getProperties()); > > } > > > > private void persistInTransaction(TestEntity item) { > > OpenJPAEntityManager em = (OpenJPAEntityManager) factory > > .createEntityManager(); > > em.getTransaction().begin(); > > em.persist(item); > > em.getTransaction().commit(); > > em.close(); > > } > > > > private void createEntities() { > > for (int i = 0; i < 100; i++) { > > TestEntity entity = new TestEntity(); > > entity.getStrings().put("a", "test " + i); > > entity.getStrings().put("b", "another test " + i); > > persistInTransaction(entity); > > } > > } > > > > private List<TestEntity> findAllEntities() { > > OpenJPAEntityManager em = (OpenJPAEntityManager) factory > > .createEntityManager(); > > em.getTransaction().begin(); > > String query = "SELECT z FROM " + > > TestEntity.class.getSimpleName() > > + " z"; > > List<TestEntity> result = em.createQuery(query, > > TestEntity.class) > > .getResultList(); > > em.getTransaction().commit(); > > em.close(); > > return result; > > } > > > > public static void main(String[] args) { > > MapPerformanceTest t = new MapPerformanceTest(); > > t.createEntityManagerFactory(); > > t.createEntities(); > > System.err.println("----------- find all -----------"); > > t.findAllEntities(); > > } > > } > > > > > > Henno Vermeulen > > > > -----Oorspronkelijk bericht----- > > Van: Rick Curtis [mailto:[email protected]] > > Verzonden: woensdag 16 februari 2011 16:49 > > Aan: [email protected] > > Onderwerp: Re: N+1 select problem for Map no matter what I try > > > > Can you try using @PersistentMap(elementCascade = > > CascadeType.PERSIST,fetch=FetchType.EAGER) rather than > @ElementCollection? > > I > > don't see the N+1 select problem in my tests when using the persistentmap > > annotation. > > > > Thanks, > > Rick > > > > On Wed, Feb 16, 2011 at 8:36 AM, Henno Vermeulen <[email protected] > > >wrote: > > > > > When I have a Map inside a TestEntity (mapped either with @OneToMany or > > > @ElementCollection), OpenJPA 2 always performs N + 1 selects when I do > > the > > > simple query "SELECT z FROM TestEntity z". > > > > > > A solution to this would of course be great, but I would also be very > > happy > > > if an OpenJPA developer could quickly try this out and confirm to me > > whether > > > or not this is indeed an issue with OpenJPA or that it is simply > expected > > > behavior. > > > > > > Regards, > > > Henno Vermeulen > > > > > > (p.s. I have tried many settings and the problem occurs no matter what > I > > > try. See https://issues.apache.org/jira/browse/OPENJPA-1920 and my > > > unanswered post "preventing N+1 select performance problem on maps"). > > > > > > > > >
