Unnecessary updates during flush operation.
-------------------------------------------
Key: OPENJPA-444
URL: https://issues.apache.org/jira/browse/OPENJPA-444
Project: OpenJPA
Issue Type: Bug
Components: kernel
Affects Versions: 1.0.1
Environment: OpenJPA without field tracking. (JDK 5.0 )
Reporter: Sławomir Wojtasiak
OpenJPA performs unnecessary updates during flush operation. For example:
When we are trying to persist versioned entity with collection of other
entities:
|Article|1-------------*|Quantity| ( Relation owner. )
************ CODE *************
EntityManagerFactory factory = Persistence.createEntityManagerFactory(
"testjpa", System.getProperties() );
EntityManager em = factory.createEntityManager();
em.getTransaction().begin();
Article a = new Article();
a.setName( "atricle" );
Quantity q = new Quantity();
q.setName( "quantity" );
q.setArticle( a );
a.getQuantities().add( q );
em.persist( a );
em.flush();
em.flush();
************* END OF CODE ************
Following queries are generated after first flush operation:
SELECT SEQUENCE_VALUE FROM OPENJPA_SEQUENCE_TABLE WHERE ID = ? FOR UPDATE
[params=(int) 0]
UPDATE OPENJPA_SEQUENCE_TABLE SET SEQUENCE_VALUE = ? WHERE ID = ? AND
SEQUENCE_VALUE = ? [params=(long) 2651, (int) 0, (long) 2601]
SELECT SEQUENCE_VALUE FROM OPENJPA_SEQUENCE_TABLE WHERE ID = ? FOR UPDATE
[params=(int) 0]
UPDATE OPENJPA_SEQUENCE_TABLE SET SEQUENCE_VALUE = ? WHERE ID = ? AND
SEQUENCE_VALUE = ? [params=(long) 2701, (int) 0, (long) 2651]
INSERT INTO Article (id, name, version) VALUES (?, ?, ?) [params=(long) 2601,
(String) atricle, (int) 1]
INSERT INTO Quantity (id, name, version, article_id) VALUES (?, ?, ?, ?)
[params=(long) 2651, (String) quantity, (int) 1, (long) 2601]
Everything looks ok but after next flush we will get version update:
UPDATE Article SET version = ? WHERE id = ? AND version = ? [params=(int) 2,
(long) 2601, (int) 1]
I am not completely sure that this analysis is correct, but I hope it helps
anyway:
During persist operation SaveFieldManager sets collection of quantities as
unloaded and unsaved field (Because this field is mutable). During next flush,
StateManager checks which fields are dirty by comparing its values to those
stored by SaveFieldManager. Method dirtyCheck() of the StateManager is
responsible for that. (It's necessary taking into consideration fact that I do
not use OpenJPA enhancer with JDK 5.0). SaveFieldManager always returns false
from its isFieldEqual() method because this collection (Collection of
quantities) is treated as unsaved ( Comment from OpenJPA code: if the field is
not available, assume that it has changed) so StateManager sets it as dirty and
clears its flush bit. Then AbstractUpdateManager try to add UPDATE_ACTION for
this dirty collection, but with no effect because this field is not set as
updatable and insertable ( I think so. ). In next step AbstractUpdateManager
adds UPDATE_ACTION for version field because StateManager is marked as dirty.
It causes unnecessary update of entity version field because nothing changed in
the database.
I didn't check how it works with field tracking.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
