PM34867: LAZY FETCHING OF THE OBJECTS RETURNS MULTIPLE OBJECTS

Fixes are available

APAR status

Closed as program error.

Error description

Single Table Inheritance Strategy causes JPA entity identity
issues.

Local fix

Problem summary

****************************************************************
* USERS AFFECTED:  All users of IBM WebSphere Application      *
*                  Server V7.0.0 who make use of a Java        *
*                  Persistence API (JPA) single table          *
*                  inheritance strategy.                       *
*                                                              *
****************************************************************
* PROBLEM DESCRIPTION: Single Table Inheritance Strategy       *
*                      causes JPA entity identity issues.      *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
Take the following three entities and notice the
inheritance/hierarchy:

@Entity
@Inheritance
public class ParentRecord {

    @Id
    private long id;

    //Changing EAGER and LAZY effects the tests
    @OneToOne(fetch=FetchType.LAZY)
    ParentRecord parent;
..........
}



@Entity
public class HeaderRecord extends ParentRecord {

    //Changing EAGER and LAZY effects the tests
    @OneToOne(cascade=CascadeType.ALL, fetch=FetchType.EAGER)
    ControlRecord controlRecord;
.....
}



@Entity
public class ControlRecord extends ParentRecord{
    //intentionally empty
}



Notice that ParentRecord uses @Inheritance.  By default,
@Inheritance uses an InheritanceType.SINGLE_TABLE as the
default strategy (which plays a role in this issue).  With
these entities, take this test:


//Find an existing HeaderRecord; assume one exists with id 10
HeaderRecord hrSaved = em.find(HeaderRecord.class, 10);

//Now, get a HeaderRecord from the relationship
//with ControlRecord
HeaderRecord hrFromControl = (HeaderRecord)
hrSaved.getControlRecord().getParent();

//Compare the two header objects; they are expected to
//be identical as they have same primary key.
assertTrue(hrSaved == hrFromControl);


With this test, the 'assertTrue' method will fail as the two
HeaderRecord objects are not identical.  This is due to a bug
in OpenJPA code when an inheritance strategy of
InheritanceType.SINGLE_TABLE is used.  As the test shows, the
same HeaderRecord is retrieved in two ways: by a find method,
and by a getter method to traverse the relationship.
These methods should return the same identical
entity/object. However, there is a bug in the OpenJPA code
such that the same entity is not found by OpenJPA code, as
such another copy of the entity is retrieved from the
database.  Finally, as the comments in the entities above
suggest, the FetchType used plays a role in the outcome of the
test.  Using a FetchType of EAGER on both entities will allow
the test to pass.

Problem conclusion

With this fix, code has been added to ensure that the same
entity identity is used and found regardless of the means by
which the entity is retrieved (that is, finder or getter).

The fix for this APAR is currently targeted for inclusion in
Service Level (Fix Pack) 7.0.0.19 of WebSphere Application
Server version 7.0.0.

Please refer to the recommended updates page for delivery
information:
http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980

Temporary fix

Comments

APAR Information

APAR number
PM34867
Reported component name
WEBSPHERE APP S
Reported component ID
5724J0800
Reported release
700
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2011-03-15
Closed date
2011-03-31
Last modified date
2011-03-31

APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:

Fix information

Fixed component name
WEBSPHERE APP S
Fixed component ID
5724J0800

Applicable component levels

R700 PSY
UP

[{"Business Unit":{"code":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SSEQTP","label":"WebSphere Application Server"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"7.0","Line of Business":{"code":"LOB45","label":"Automation"}}]

Document Information

Modified date:
27 October 2021

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PM34867: LAZY FETCHING OF THE OBJECTS RETURNS MULTIPLE OBJECTS

Fixes are available

Subscribe

APAR status

Closed as program error.

Error description

Local fix

Problem summary

Problem conclusion

Temporary fix

Comments

APAR Information

APAR number

Reported component name

Reported component ID

Reported release

Status

PE

HIPER

Special Attention

Submitted date

Closed date

Last modified date

APAR is sysrouted FROM one or more of the following:

APAR is sysrouted TO one or more of the following:

Fix information

Fixed component name

Fixed component ID

Applicable component levels

R700 PSY

Document Information

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