[hibernate-issues] [Hibernate-JIRA] Created: (HHH-4477) DiscriminatorValue could be used in WHERE Statement in OneToMany Joins to Speed up the Result

[Robert Bartl (JIRA)]

DiscriminatorValue could be used in WHERE Statement in OneToMany Joins to Speed up the Result
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                 Key: HHH-4477
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-4477
             Project: Hibernate Core
          Issue Type: Improvement
    Affects Versions: 3.3.1
            Reporter: Robert Bartl


Currently the DiscriminatorValue is not used in Queries that fetch multiple Entities.
Adding this could increase the Speed of the Fetch as another index could be used.

Example:

@Entity(name="Issues")
public class Issue
{
  @Id
  @Column(nullable = false, insertable = true, updatable = false)
  private int id;
  @OneToMany(cascade=CascadeType.ALL,fetch=FetchType.LAZY,mappedBy="objectId")
  private List<TicketTransaction> transactions;
  public List<TicketTransaction> getTransactions()
  {
    return transactions;
  }
}

@Entity(name = "Transactions")
@Table(name = "Transactions")
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "ObjectType", discriminatorType = DiscriminatorType.STRING, length = 20)
@DiscriminatorValue("null")
public abstract class Transaction  {
  @Id
  @Column(nullable = false, insertable = true, updatable = false)
  private int id;
}

@DiscriminatorValue("Issue")
@Entity
public final class TicketTransaction extends Transaction {
  @Column(nullable = true, insertable = false, updatable = false, name = "ObjectId")
  private int objectId;
}

ObjectId is in ticketTransaction class because of HBX-1075 Bug, should have been in Transaction class.


This setup results in the following Query if Issue.getTransactions() is called:
 select transactio0_.ObjectId as ObjectId1_, transactio0_.id as id1_, transactio0_.ObjectType as ObjectType4_0_, transactio0_.ObjectId as ObjectId4_0_ from Transactions transactio0_ where transactio0_.ObjectId=4236

missing: "AND ObjectType = 'Issue'"


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