[Persistence, JBoss/CMP, Hibernate, Database] - @OneToOne and SELECT (1+n) problem
by Lupson
Lots of searching in various resources havn't solved this issue for me so here goes..:
Environment:
JBoss 4.0.5.GA
Seam 1.2.1
Oracle 10 running ojdbc14.jar
Basically, I have two entities, let's call them PERSON and PERSON_METADATA. They have a bi-directional @OneToOne relation.
Problem: I have 1000 PERSONs and I issue a JPA/HQL query such as: entityManager.createQuery("SELECT p FROM Person p").getResultList();
Looking at the SQL debug output in the log, this simple JPA query performs 1001 SELECTs instead of performing a JOIN (or LEFT JOIN if optional=true).
I've fiddled around with various FetchType.EAGER/LAZY, @LazyToOne, @Fetch(FetchMode.EAGER) etc. settings, but still I always get this 1+n number of queries, regardless of how I annotate the @OneToOne relation.
Any ideas on how to get JPA/Hibernate to EAGER load this using a single JOIN?
Thanks!
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18 years
[EJB 3.0] - Basic EJB - cant be invoked from client
by r12345_2003
Hi,
I am trying to create a simple EJB and deploy to JBoss. The EJB is created and deployed to JBoss successfully. However when i try to invoke it from a standalone client i am unable to do so. I get a javax.naming.CommunicationException: exception.
Following is the code for my EJB Local interface:
| import javax.ejb.Local;
|
| @Local
| public interface CalculatorLocal
| {
| public float add(float x, float y);
| }
|
Following is the code for the EJB:
| import javax.ejb.Local;
| import javax.ejb.Stateless;
|
|
| @Stateless
| public class CalculatorBean implements CalculatorLocal
| {
|
| public float add(float x, float y)
| {
| return x+y;
| }
|
| }
|
Following is the code for the client:
| import javax.naming.InitialContext;
|
| import uk.co.autotrader.ejb3.stateless.CalculatorLocal;
|
|
| public class CalculatorClient
| {
| public static void main(String args[]){
| try {
| InitialContext ic = new InitialContext();
| CalculatorLocal calculator = (CalculatorLocal)ic.lookup("CalculatorBean/local");
| float total = calculator.add(2F, 5F);
| System.out.println("sum is "+total);
| }
| catch(Exception e){
| System.out.println("Exception "+e);
| }
| }
| }
|
Following is the exception message at the console when the client is run:
| javax.naming.CommunicationException: Receive timed out [Root exception is java.net.SocketTimeoutException: Receive timed out]
|
I have included the necessary JAR files and also have jndi.properties in my client code class path (After referring http://www.jboss.org/?module=bb&op=viewtopic&t=57223)
I am using JBoss 4.2.2 GA.
Can anyone help?
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18 years