[eclipselink-users] Uregntly need help for thesis: Batch reading of coll

["Mario Schwarz" <Mario.Sandro.Schwarz@xxxxxx>]

Hi everybody.

I have to do a run time comparison on Eclipselink and Hibernate for my Bachelor Thesis. I really have an urgent problem, I don't get BatchReading to work correctly.

I implemented use-case based test cases that call specific methods of a  SessionBean called "PartnerService". PartnerService acts as a Facade and manages the transactions (@TransactionAttributeType.REQUIRED). It calls methods on a DAO called "PartnerDAO". PartnerDAO requires an open transaction (@TransactionAttributeType.MANDATORY)

I have the following NamedQuery which retrieves me all partners with their addresses and their roles:

@NamedQuery(name = "getAllPartnersWithAdressesAndRoles", query = "SELECT p FROM Partner as p ", hints = {
@QueryHint(name = QueryHints.LEFT_FETCH, value = "p.roles"),
@QueryHint(name = QueryHints.LEFT_FETCH, value = "p.addresses"),
@QueryHint(name = QueryHints.JDBC_FETCH_SIZE, value = "1000") })

Now I also want to retrieve the bank account of the specific role "employee"  which is a unidirectional onetoone-relation. In the PartnerDAO-method I do the following:

public List<Partner> findAllPartners() {
  Query q = em.createNamedQuery("getAllPartnersWithAdressesAndRoles");
  // results in just 1 SELECTs
  List<Partner> l = q.getResultList();
  for (Partner partner : l) {
    for (Role role : partner.getRoles()) {
      // results in l.size() SELECTs
      BankAccount ba = ((Employee) role).getBankAccount();
    }
  }
}

My goal is to iterate over all roles and retrieve all BankAccounts in a single SELECT. I guess the problem is, that BankAccount has no ForeignKey of its Employee. With Hibernate it works though. Oh, by the way, I am not able to change the mapping to bidirectional anymore!

Any help is more than appeciated!
Thanks
Mario  


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