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Re: [eclipselink-users] Order of persist operations
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Can you provide a specific test-case where the order actually causes a problem?
The JPA specification allows a persistence provider to order statements in the
way that is most efficient for it. This, in fact, is essential to solving the
very problem you are worried about. i.e. A JPA provider has to be able to
compute an order of statements that allow foreign key constraints to be properly
satisfied. As long as your entities are configured so that JPA is made aware of
all your constraints, the order of statements should not cause any problems of
that type.
The power of this functionality is that when you are writing your JPA code, you
do not have to think about the database constraints, you just manipulate your
objects and the order will be taken care of.
-Tom
On 17/01/2013 6:27 AM, Deyan Tsvetanov wrote:
Well, the order that EclipseLink chooses is RANDOM :)
It is a fairly simple example, only 1 entity with only 1 column.
I'd really expect that the INSERT statements are executed in same order as the
persist() calls.
My real-life use case is importing data from an XML file into the database.
There are relations and FKs in my database and when exported and re-imported the
order of the XML entries, persist() calls and INSERT statements is critical.
EclipseLink basically inserts each XML entry randomly. Currently the only
workaround is to flush after each persist call. It could work for few hundred
calls,
but not for few thousand.
JPA says nothing about the order of the database operations. When writing the
spec they probably have assumed that it would be logical to execute the database
operations in the
same order as the persist() or merge() calls.
This is not the case of mixed remove(), persist() and merge() calls, in our case
we have only persist() calls and the case is very simple.
Best regards,
Deyan
On Jan 17, 2013, at 13:19 , Wim Bervoets <wbervoets@xxxxxxxxx
<mailto:wbervoets@xxxxxxxxx>> wrote:
If you want to know the order in which the rows were inserted I use @OrderColumn
(eg. in combinantion with INDEX(..) function in a JPQL for example).
I think that EclipseLink can choose the order in which it commits the entities
to the database... (I haven't read the JPA spec so this is an assumption)
Wim
On Thu, Jan 17, 2013 at 12:09 PM, Deyan Tsvetanov <deyan@xxxxxxxxxxxx
<mailto:deyan@xxxxxxxxxxxx>> wrote:
Hibernate persists the entities in the correct order:
2:57:58,867 TRACE TypeFactory:72 - Scoping types to session factory
org.hibernate.internal.SessionFactoryImpl@395fa2b5
Hibernate: insert into ROLE (ID) values (?)
12:57:59,365 TRACE BasicBinder:83 - binding parameter [1] as [VARCHAR] - TEST0
Hibernate: insert into ROLE (ID) values (?)
12:57:59,369 TRACE BasicBinder:83 - binding parameter [1] as [VARCHAR] - TEST1
Hibernate: insert into ROLE (ID) values (?)
12:57:59,371 TRACE BasicBinder:83 - binding parameter [1] as [VARCHAR] - TEST2
Hibernate: insert into ROLE (ID) values (?)
12:57:59,372 TRACE BasicBinder:83 - binding parameter [1] as [VARCHAR] - TEST3
Hibernate: insert into ROLE (ID) values (?)
12:57:59,373 TRACE BasicBinder:83 - binding parameter [1] as [VARCHAR] - TEST4
Hibernate: insert into ROLE (ID) values (?)
12:57:59,375 TRACE BasicBinder:83 - binding parameter [1] as [VARCHAR] - TEST5
Hibernate: insert into ROLE (ID) values (?)
12:57:59,376 TRACE BasicBinder:83 - binding parameter [1] as [VARCHAR] - TEST6
Hibernate: insert into ROLE (ID) values (?)
12:57:59,377 TRACE BasicBinder:83 - binding parameter [1] as [VARCHAR] - TEST7
Hibernate: insert into ROLE (ID) values (?)
12:57:59,378 TRACE BasicBinder:83 - binding parameter [1] as [VARCHAR] - TEST8
Hibernate: insert into ROLE (ID) values (?)
12:57:59,380 TRACE BasicBinder:83 - binding parameter [1] as [VARCHAR] - TEST9
On Jan 17, 2013, at 12:19 , Deyan Tsvetanov <deyan@xxxxxxxxxxxx
<mailto:deyan@xxxxxxxxxxxx>> wrote:
Hi guys,
I am experiencing a weird imho behaviour of Eclipselink and I'd really like
to hear some other opinions .
I have a pretty simple entity with assigned IDs;
@Entity@Table(name="ROLE")
public class Role implements Serializable {
privatestaticfinallongserialVersionUID= 1L;
@Id @Column(name="ID", length=20, nullable=false)
public String id;
}
I am executing the following operations:
public static void main(String[] args) {
EntityManagerFactory emf =
Persistence.createEntityManagerFactory("EclipseLinkJPATest");
EntityManager em = emf.createEntityManager();
em.getTransaction().begin();
for (int i = 0; i < 10; i++) {
Role r = new Role();
r.id = "TEST" + i;
em.persist(r);
}
em.getTransaction().commit();
em.close();
emf.close();
}
And I'd expect that the INSERT queries will be executed in the same order as
the persist() method is called:
TEST0, TEST1, TEST2 , etc.
But in the real life the insert queries are in a random order every time:
EL Fine]: sql: 2013-01-17
12:13:58.11--ClientSession(1694665796)--Connection(1795160456)--INSERT INTO
ROLE (ID) VALUES (?)
bind => [TEST1]
[EL Fine]: sql: 2013-01-17
12:13:58.113--ClientSession(1694665796)--Connection(1795160456)--INSERT INTO
ROLE (ID) VALUES (?)
bind => [TEST6]
[EL Fine]: sql: 2013-01-17
12:13:58.114--ClientSession(1694665796)--Connection(1795160456)--INSERT INTO
ROLE (ID) VALUES (?)
bind => [TEST2]
[EL Fine]: sql: 2013-01-17
12:13:58.115--ClientSession(1694665796)--Connection(1795160456)--INSERT INTO
ROLE (ID) VALUES (?)
bind => [TEST7]
[EL Fine]: sql: 2013-01-17
12:13:58.117--ClientSession(1694665796)--Connection(1795160456)--INSERT INTO
ROLE (ID) VALUES (?)
bind => [TEST4]
[EL Fine]: sql: 2013-01-17
12:13:58.121--ClientSession(1694665796)--Connection(1795160456)--INSERT INTO
ROLE (ID) VALUES (?)
bind => [TEST8]
[EL Fine]: sql: 2013-01-17
12:13:58.123--ClientSession(1694665796)--Connection(1795160456)--INSERT INTO
ROLE (ID) VALUES (?)
bind => [TEST3]
[EL Fine]: sql: 2013-01-17
12:13:58.124--ClientSession(1694665796)--Connection(1795160456)--INSERT INTO
ROLE (ID) VALUES (?)
bind => [TEST9]
[EL Fine]: sql: 2013-01-17
12:13:58.126--ClientSession(1694665796)--Connection(1795160456)--INSERT INTO
ROLE (ID) VALUES (?)
bind => [TEST5]
[EL Fine]: sql: 2013-01-17
12:13:58.127--ClientSession(1694665796)--Connection(1795160456)--INSERT INTO
ROLE (ID) VALUES (?)
bind => [TEST0]
As you can see the order if insert queries is:
TEST1, TEST6, TEST2, TEST7, TEST4, etc.
That is really weird and wrong ! :)
I dug a lot and could not find a solution.
Please help :)
Thanks in advance,
Deyan
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