title: em.persist seems doesn't persist data on postgreSQL db
body: <p>I've got a simple java main which must write bean data on a PostgreSQL database. I use Entity manager to persist or update object. I use hibernate and toplink driver connection which are specified in persistence.xml file. 
  When I call em.persist(obj), nothing is saved on database, I don't know why. here is my simple code:</p>
  
  <pre><code>private static void importa(FileReader f) throws IOException {
  
    EntityManagerFactory emf = Persistence
    .createEntityManagerFactory("orpt2");
    EntityManager em = emf.createEntityManager();
  
  dispositivoMedico = new DispositivoMedico();
  dispositivoMedico.setCategoria("prova");
  dispositivoMedico.setCodice("323");
  em.persist(dispositivoMedico);
  </code></pre>
  
  <p>And here is my persistence.xml</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;persistence version="1.0"
   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/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"&gt;
   &lt;persistence-unit name="orpt2"&gt;
     &lt;class&gt;it.ariadne.orpt2.entities.AccessoriScheda&lt;/class&gt;
      &lt;class&gt;it.ariadne.orpt2.entities.CampiSchede&lt;/class&gt;
    &lt;class&gt;it.ariadne.orpt2.entities.CampiSchedeSalvati&lt;/class&gt;
    &lt;class&gt;it.ariadne.orpt2.entities.CampoAggiuntivo&lt;/class&gt; 
     &lt;class&gt;it.ariadne.orpt2.entities.Categorie&lt;/class&gt;
    &lt;class&gt;it.ariadne.orpt2.entities.CategorieCampi&lt;/class&gt;
    &lt;class&gt;it.ariadne.orpt2.entities.CategorieCampiPK&lt;/class&gt;
    &lt;class&gt;it.ariadne.orpt2.entities.ClasseCivab&lt;/class&gt; 
    &lt;class&gt;it.ariadne.orpt2.entities.DecodificaStato&lt;/class&gt;
    &lt;class&gt;it.ariadne.orpt2.entities.DispositivoMedico&lt;/class&gt;
     &lt;class&gt;it.ariadne.orpt2.entities.Ente&lt;/class&gt;
      &lt;class&gt;it.ariadne.orpt2.entities.FormaNegoziazione&lt;/class&gt;
    &lt;class&gt;it.ariadne.orpt2.entities.Fornitore&lt;/class&gt; 
    &lt;class&gt;it.ariadne.orpt2.entities.LogSession&lt;/class&gt; 
    &lt;class&gt;it.ariadne.orpt2.entities.Modello&lt;/class&gt; 
    &lt;class&gt;it.ariadne.orpt2.entities.Periodicita&lt;/class&gt;
    &lt;class&gt;it.ariadne.orpt2.entities.Produttore&lt;/class&gt;
     &lt;class&gt;it.ariadne.orpt2.entities.Ruolo&lt;/class&gt;
    &lt;class&gt;it.ariadne.orpt2.entities.RuoloPK&lt;/class&gt;
    &lt;class&gt;it.ariadne.orpt2.entities.RuoloUtente&lt;/class&gt; 
    &lt;class&gt;it.ariadne.orpt2.entities.Scheda&lt;/class&gt;
    &lt;class&gt;it.ariadne.orpt2.entities.SchedaSalvata&lt;/class&gt;
    &lt;class&gt;it.ariadne.orpt2.entities.Tipologia&lt;/class&gt; 
     &lt;class&gt;it.ariadne.orpt2.entities.Utente&lt;/class&gt;
  
    &lt;!-- locale 2010--&gt;&lt;!-- optsanmatteo_prova300310 --&gt;
     &lt;properties&gt;
  
     &lt;property name="hibernate.connection.driver_class"
      value="org.postgresql.Driver" /&gt;
  
     &lt;property name="hibernate.connection.url"
      value="jdbc:postgresql://localhost:5432/optsanmatteo_provaHash" /&gt;
  
     &lt;property name="hibernate.connection.password"
      value="s4sh4gr3y" /&gt;
  
     &lt;property name="hibernate.connection.username"
      value="sanmatteo" /&gt;
  
     &lt;property name="hibernate.dialect"
      value="org.hibernate.dialect.PostgreSQLDialect" /&gt;
  
  
     &lt;property name="toplink.logging.level" value="WARNING" /&gt;
     &lt;property name="toplink.jdbc.driver"
      value="org.postgresql.Driver" /&gt;
  
     &lt;property name="toplink.jdbc.url"
      value="jdbc:postgresql://localhost:5432/optsanmatteo_provaHash" /&gt;
  
     &lt;property name="toplink.jdbc.password" value="s4sh4gr3y" /&gt;
  
     &lt;property name="toplink.jdbc.user"
      value="sanmatteo" /&gt;
    &lt;/properties&gt;
  
   &lt;/persistence-unit&gt;
  
  &lt;/persistence&gt;
  </code></pre>
  
  <p>Thank you for your help.</p>
  
  <p>Mario</p>