Develop Reference

org.hibernate.AssertionFailure Issue when getting sequence value

I am trying to insert multiple records in a table using loop and getting sequence number for that using below method. It is getting sequence number for very first time alone and during next iteration below exception is coming.Please help in resolving this
14:03:51.928 [http-nio-8080-exec-5] ERROR org.hibernate.AssertionFailure - HHH000099: an assertion failure occured (this may indicate a bug in Hibernate, but is more likely due to unsafe use of the session): org.hibernate.AssertionFailure: possible non-threadsafe access to session
14:03:51.938 [http-nio-8080-exec-5] ERROR u.s.m.e.p.o.b.c.ORBudgetController - 2020/08/26_14:03:51.938|1|pa23690|bearer 6d7417d8-6835-485e-956d-c362cb7bce2b|createRecord|possible non-threadsafe access to session
#Override
public int getNextSequenceNumber(String seqName) {
int nextValue = 0;
String strQuery = "SELECT " + seqName + ".NEXTVAL FROM DUAL";
Query q = entityManager.createNativeQuery(strQuery);
BigDecimal bd = (BigDecimal) q.getSingleResult();
nextValue = bd.intValue();
return nextValue;
}

You need to generate the sequence automatically, do it manually is a bad practice and can bring you problems in the future. There are several JPA strategies to automatically generate the sequence, this, for example, is The Sequence Strategy
#Entity
// Define a sequence - might also be in another class:
#SequenceGenerator(name="seq", initialValue=1, allocationSize=100)
public class EntityWithSequenceId {
// Use the sequence that is defined above:
#GeneratedValue(strategy=GenerationType.SEQUENCE, generator="seq")
#Id long id;
}
You can also use The Auto Strategy
#Entity
public class EntityWithAutoId1 {
#Id #GeneratedValue(strategy=GenerationType.AUTO) long id;
}

Generate non-conflicting non-primary-key unique "composite ids" in Hibernate

I'm not sure if my question title is correct, if not, please correct it.
Anyway, long story short, I have sellers, each seller belongs to a company, each seller has an ID as a primary key which is auto-incrementing and a seller-number which is unique per company.
id seller-number company-id
0 0 1
1 1 1
2 2 1
3 0 2
4 1 2
4 2 2
Here's my Seller entity:
#Entity
#Configurable
#Table(name="Seller", uniqueConstraints = {#UniqueConstraint(columnNames= {"company", "sellerNumber"})})
public class Seller implements Serializable {
#PersistenceContext
transient EntityManager entityManager;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "id")
private Long id;
#Version
#Column(name = "version")
private Integer version;
#ManyToOne
private Company company;
private Long sellerNumber;
...
Now when creating a seller, I do the following:
#Transactional
private void createSeller(SellerRequest request, SellerResponse response, Session session) {
Seller seller = new Seller();
// generate seller number
TypedQuery<Long> query = Seller.entityManager().createQuery("SELECT max(o.sellerNumber) + 1 FROM Seller AS o WHERE o.company=:company", Long.class);
query.setParameter("company", session.getCompany());
Long sellerNumber = query.getSingleResult();
seller.setSellerNumber(sellerNumber == null ? 1 : sellerNumber);
...
seller.setCompany(session.getCompany());
// persist
seller.persist();
...
The seller numbers I'm getting back is fine, until I start doing a lot of concurrent creates. If two creates happen at the exact same moment, I get a org.hibernate.exception.ConstraintViolationException
The requirements are that I only use an ID as a primary key, no composite primary keys. So taking these constraints into account, how should I be creating these entities so that they have unique seller numbers inside their companies and avoid ConstraintViolationExceptions ?
Is using max(o.sellerNumber) + 1 the right way to go or is there a better way to do this?

The hackish way to accomplish this was to simply catch the ConstraintViolationException and recursively retry the create, increment a retry counter in the request so that it's possible to bail if the number of recursive retries becomes too much.
try {
createSeller(...);
} catch(org.springframework.orm.jpa.JpaSystemException e){
if (e.contains(org.hibernate.exception.ConstraintViolationException.class)){
return thisMethodThatCallsCreateSeller(...);
} else {
throw e;
}
}
On small loads, there's almost no contention, when throwing heavy load at it, there's a little bit of a slowdown as contention causes multiple calls to try and create the seller with multiple ConstraintViolations being caught. Gets the job done though.

Id of entity is different after hibernate save from oracle database with sequence autogeneration id

Entity with id autogenerated from oracle trigger sequence.
#Entity
#Table(name = "REPORT", schema = "WEBPORTAL")
public class Report {
private Integer id;
....
#Id
#GeneratedValue(strategy = GenerationType.SEQUENCE, generator="report_sequence")
#SequenceGenerator(name="report_sequence", sequenceName = "report_id_seq")
#Column(name="REPORT_ID", unique = true, nullable = false)
public Integer getId() {
return id;
}
....
}
Service
#Service("reportService")
public class ReportServiceImpl implements ReportService {
....
#Transactional(readOnly=false)
public void saveOrUpdate(Report report) {
reportDAO.saveOrUpdate(report);
}
}
DAO
#Repository
public class ReportDAOImpl implements ReportDAO {
....
#Override
public Report save(Report report) {
try {
Session session = sessionFactory.getCurrentSession();
session.save(report);
} catch (Exception e) {
logger.error("error", e);
}
return report;
}
}
And When I call service's saveOrUpdate and then try to reach id of entity I get different value than persisted in database. Values on database with autogeneration all is ok. Any suggestions?
reportService.saveOrUpdate(report);
System.out.println(report.getId());
prints: 4150
but saved id in database is: 84
NOTE: My purpose to get Id comes from that I wanted to save childs with cascade. But foreign key on child was different in database(the values of id that I get with getId()).
And Id generated in database is incremented by 2. EX: 80, 82, 84.
UPDATE:
Oracle trigger for sequence generation
CREATE OR REPLACE TRIGGER REPORT_ID_TRIG
BEFORE INSERT ON WEBPORTAL.REPORT
FOR EACH ROW
BEGIN
SELECT report_id_seq.NEXTVAL
INTO :new.report_id
FROM dual;
END;

ANSWER: Trigger should check if id is null
CREATE OR REPLACE TRIGGER REPORT_ID_TRIG
BEFORE INSERT ON WEBPORTAL.REPORT
FOR EACH ROW
WHEN (new.report_id is null)
BEGIN
SELECT report_id_seq.NEXTVAL
INTO :new.report_id
FROM dual;
END;
DESCRIPTION:
#GeneratedValue is not just a sequence generator. It's bit of HiLo algorithm.When it first requests id from database it multiplies it with 50(it can differ) and next 50 new entities will be given ids consequently, and than next request to database. This is to decrease request to database.
The numbers that I get from java was right numbers that should be saved on report.
Without id null value check Hibernate firstly requested for id from database and sequence.nextval called. When hibernate was persisting it(completing transaction) the database called sequence.next second time and set that value to database. So on ReportDetails there was true id value of report and on the Report id it was id set from database.

The problem is that two separate mechanisms are in place to generate the key:
one at Hibernate level which is to call a sequence and use the value to populate an Id column and send it to the database as the insert key
and another mechanism at the database that Hibernate does not know about: the column is incremented via a trigger.
Hibernate thinks that the insert was made with the value of the sequence, but in the database something else occurred. The simplest solution would probably be to remove the trigger mechanism, and let Hibernate populate the key based on the sequence only.
Another Solution:
check your trigger definition that should be in this format
(WHEN (new.report_id is null) ) is important.
CREATE OR REPLACE TRIGGER TRIGGER_NAME
BEFORE INSERT ON TABLE_NAME
FOR EACH ROW
WHEN (new.id is null)
BEGIN
SELECT SEQUENCE_NAME.NEXTVAL
INTO :new.id
FROM dual;
END

Performance OpenJPA query (3000+ records) is slow

I'm using Websphere Application Server 7 with buildin OpenJPA 1.2.3 and an Oracle database. I have the following entity:
#NamedNativeQuery(name=Contract.GIVE_ALL_CONTRACTS,
query="SELECT number, name \n" +
"FROM contracts \n" +
"WHERE startdate <= ?1 \n" +
"AND enddate > ?1",
resultSetMapping = Contract.GIVE_ALL_CONTRACTS_MAPPING)
#SqlResultSetMapping(name = Contract.GIVE_ALL_CONTRACTS_MAPPING,
entities = { #EntityResult(entityClass = Contract.class, fields = {
#FieldResult(name = "number", column = "number"),
#FieldResult(name = "name", column = "name")
})
})
#Entity
public class Contract {
public static final String GIVE_ALL_CONTRACTS = "Contract.giveAllContracts";
public static final String GIVE_ALL_CONTRACTS_MAPPING = "Contract.giveAllContractsMapping";
#Id
private Integer number;
private String name;
public Integer getNumber() {
return number;
}
public String getName() {
return name;
}
}
And the following code to retrieve the contracts:
Query query = entityManager.createNamedQuery(Contract.GIVE_ALL_CONTRACTS);
query.setParameter(1, referenceDate);
List contracts = query.getResultList();
entityManager.clear();
return contracts;
The retrieved contracts are passed to a webservice.
Executing this query in Oracle developer takes around 0,35 seconds for 3608 records.
The call to query.getResultList() takes around 4 seconds.
With a logger in the constuctor of the entity, it logs that there are about 10-20 entities created with the same timestamp. Then 0,015 seconds it does something else. I guess OpenJPA stuff.
Is there a way to speed up OpenJPA? Or is the only solution caching?

Object creation may have its fair share in the performance hit. While running your code in the server, you're not only querying the database but also you allocate memory and create a new Contract object for each row. An expanding heap or garbage collection cycle may count for idle periods that you observed.
I'd suggest you skim through OpenJPA documentation on how to process large results sets.

I suggest you downloading VisualVM and set up a profiling for the packages involved. VisualVM can show the time spent in different methods that will sum up to 0.35sec in your case theoretically. You will be able to analyze the distribution of the total time between your code, OpenJPA and the network IO. This will help you to identify the bottleneck.

Hibernate: same generated value in two properties

I want the first to be generated:
#Id
#Column(name = "PRODUCT_ID", unique = true, nullable = false, precision = 12,
scale = 0)
#GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "PROD_GEN")
#BusinessKey
public Long getAId() {
return this.aId;
}
I want the bId to be initially exactly as the aId. One approach is to insert the entity, then get the aId generated by the DB (2nd query) and then update the entity, setting the bId to be equal to aId (3rd query). Is there a way to get the bId to get the same generated value as aId?
Note that afterwards, I want to be able to update bId from my gui.
If the solution is JPA, even better.

Choose your poison:
Option #1
you could annotate bId as org.hibernate.annotations.Generated and use a database trigger on insert (I'm assuming the nextval has already been assigned to AID so we'll assign the curval to BID):
CREATE OR REPLACE TRIGGER "MY_TRIGGER"
before insert on "MYENTITY"
for each row
begin
select "MYENTITY_SEQ".curval into :NEW.BID from dual;
end;
I'm not a big fan of triggers and things that happen behind the scene but this seems to be the easiest option (not the best one for portability though).
Option #2
Create a new entity, persist it, flush the entity manager to get the id assigned, set the aId on bId, merge the entity.
em.getTransaction().begin();
MyEntity e = new MyEntity();
...
em.persist(e);
em.flush();
e.setBId(e.getAId());
em.merge(e);
...
em.getTransaction().commit();
Ugly, but it works.
Option #3
Use callback annotations to set the bId in-memory (until it gets written to the database):
#PostPersist
#PostLoad
public void initialiazeBId() {
if (this.bId == null) {
this.bId = aId;
}
}
This should work if you don't need the id to be written on insert (but in that case, see Option #4).
Option #4
You could actually add some logic in the getter of bId instead of using callbacks:
public Long getBId() {
if (this.bId == null) {
return this.aId;
}
return this.bId;
}
Again, this will work if you don't need the id to be persisted in the database on insert.

If you use JPA, after inserting the new A the id should be set to the generated value, i tought (maybe it depends on which jpa provider you use), so no 2nd query needed. then set bld to ald value in your DAO?