JPA: Pre-allocate ID block not work fine - jpa

Question

I'm trying to manage the ID generation through the annotation #TableGenerator with allocationSize default. As I understand it, to avoid updating the row for every single identifier that gets requested, an allocation size is used. In theory, the provider should pre-allocate a block of identifiers equal to the value of allocationSize - 50 in this case - and then give out identifiers from memory as requested until the block is used up or the transaction comes to an end.
I Use Eclipselink (EL) with JBoss 7.1.
The problem is that this does not happen. Inserting 3 records in the table Students, EL pre allocates for each record a block of 50 ID, even if the transaction is the same. Then, for each record, there is always access to the table. From the logs I see 3 pre allocations and three pairs of select/update query for the ID and the IDs are generated 1- 51 -101 and the sequence has as its final value 150. Piece of log
Connection acquired from connection pool
UPDATE SEQUENCE SET SEQ_COUNT = SEQ_COUNT + ? WHERE SEQ_NAME = ?
bind => [50, TABLE_SEQ]
SELECT SEQ_COUNT FROM SEQUENCE WHERE SEQ_NAME = ?
bind => [TABLE_SEQ]
local sequencing preallocation for TABLE_SEQ: objects: 50 , first: 1, last: 50
Connection released to connection pool [default].
Connection acquired from connection pool
UPDATE SEQUENCE SET SEQ_COUNT = SEQ_COUNT + ? WHERE SEQ_NAME = ?
bind => [50, TABLE_SEQ]
SELECT SEQ_COUNT FROM SEQUENCE WHERE SEQ_NAME = ?
bind => [TABLE_SEQ]
local sequencing preallocation for TABLE_SEQ: objects: 50 , first: 51, last: 100
Connection released to connection pool [default].
Being a single transaction, I expected sequential IDs (1-2-3) and the final value of the sequence 50.
Where am I wrong? I tried to do research on the forum but I can not even solve the problem.
Below is the simple test code.
Thanks for the help.
Entity Student
#Entity
#Table(name="STUDENTS")
public class Student implements Serializable
{
private static final long serialVersionUID = 4771385985502937621L;
#TableGenerator(name="TABLE_SEQ")
#Id #Column(name="ID_STUDENT") #GeneratedValue(generator="TABLE_SEQ")
private int idStudent;
private String name;
public int getIdStudent() {
return idStudent;
}
public void setIdStudent(int idStudent) {
this.idStudent = idStudent;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name= name;
}
}
EJB
#Stateless(name="EJBStudent")
public class EJBStudent implements EJBStudentRemote
{
#PersistenceContext(unitName="JPA_Test")
private EntityManager manager;
public EJBStudent() {
}
#Override
public void insertStudents()
{
manager.getTransaction().begin();
Student student1 = new Student();
student1.setName("Anna");
manager.persist(student1);
Student student2 = new Student();
student2.setName("Paolo");
manager.persist(student2);
Student student3 = new Student();
student3.setName("Luigi");
manager.persist(student3);
manager.flush();
}
}
EDIT
#Chris thanks for response.
This is the finest log. I only noticed a major difference. For each insert, it create a different connection. However, if run the query suggested by #wypieprz first of all persist, the connection is always the same.
Invoking org.jboss.invocation.InterceptorContext$Invocation.insertStudent
[EL Finer]: connection: 2014-04-26 18:05:14.228--ServerSession(320769650)--Thread(Thread[EJB default - 1,5,EJB default])--client acquired: 1096067977
[EL Finer]: transaction: 2014-04-26 18:05:14.236--ClientSession(1096067977)--Thread(Thread[EJB default - 1,5,EJB default])--acquire unit of work: 698749338
[EL Finest]: transaction: 2014-04-26 18:05:14.237--UnitOfWork(698749338)--Thread(Thread[EJB default - 1,5,EJB default])--persist() operation called on: jpa.test.model.Student#55cdaad2.
[EL Finest]: connection: 2014-04-26 18:05:14.238--ServerSession(320769650)--Connection(118375432)--Thread(Thread[EJB default - 1,5,EJB default])--Connection acquired from connection pool [default].
[EL Finest]: query: 2014-04-26 18:05:14.24--ClientSession(1096067977)--Thread(Thread[EJB default - 1,5,EJB default])--Execute query DataModifyQuery(name="TABLE_SEQ" sql="UPDATE SEQUENCE SET SEQ_COUNT = SEQ_COUNT + #PREALLOC_SIZE WHERE SEQ_NAME = #SEQ_NAME")
[EL Finest]: connection: 2014-04-26 18:05:14.242--ClientSession(1096067977)--Thread(Thread[EJB default - 1,5,EJB default])--reconnecting to external connection pool
[EL Fine]: sql: 2014-04-26 18:05:14.249--ClientSession(1096067977)--Connection(1243300871)--Thread(Thread[EJB default - 1,5,EJB default])--UPDATE SEQUENCE SET SEQ_COUNT = SEQ_COUNT + ? WHERE SEQ_NAME = ?
bind => [50, TABLE_SEQ]
[EL Finest]: query: 2014-04-26 18:05:14.252--ClientSession(1096067977)--Thread(Thread[EJB default - 1,5,EJB default])--Execute query ValueReadQuery(name="TABLE_SEQ" sql="SELECT SEQ_COUNT FROM SEQUENCE WHERE SEQ_NAME = #SEQ_NAME")
[EL Fine]: sql: 2014-04-26 18:05:14.253--ClientSession(1096067977)--Connection(1243300871)--Thread(Thread[EJB default - 1,5,EJB default])--SELECT SEQ_COUNT FROM SEQUENCE WHERE SEQ_NAME = ?
bind => [TABLE_SEQ]
[EL Finest]: sequencing: 2014-04-26 18:05:14.256--ClientSession(1096067977)--Connection(1243300871)--Thread(Thread[EJB default - 1,5,EJB default])--local sequencing preallocation for TABLE_SEQ: objects: 50 , first: 1, last: 50
[EL Finest]: connection: 2014-04-26 18:05:14.258--ServerSession(320769650)--Connection(118375432)--Thread(Thread[EJB default - 1,5,EJB default])--Connection released to connection pool [default].
[EL Finest]: sequencing: 2014-04-26 18:05:14.259--UnitOfWork(698749338)--Thread(Thread[EJB default - 1,5,EJB default])--assign sequence to the object (1 -> jpa.test.model.Student#55cdaad2)
[org.hibernate.validator.util.Version] (EJB default - 1) Hibernate Validator 4.2.0.Final
[EL Finest]: transaction: 2014-04-26 18:05:14.325--UnitOfWork(698749338)--Thread(Thread[EJB default - 1,5,EJB default])--persist() operation called on: jpa.test.model.Student#59887d29.
[EL Finest]: connection: 2014-04-26 18:05:14.326--ServerSession(320769650)--Connection(265370795)--Thread(Thread[EJB default - 1,5,EJB default])--Connection acquired from connection pool [default].
[EL Finest]: query: 2014-04-26 18:05:14.327--ClientSession(1096067977)--Thread(Thread[EJB default - 1,5,EJB default])--Execute query DataModifyQuery(name="TABLE_SEQ" sql="UPDATE SEQUENCE SET SEQ_COUNT = SEQ_COUNT + ? WHERE SEQ_NAME = ?")
[EL Finest]: connection: 2014-04-26 18:05:14.328--ClientSession(1096067977)--Thread(Thread[EJB default - 1,5,EJB default])--reconnecting to external connection pool
[EL Fine]: sql: 2014-04-26 18:05:14.329--ClientSession(1096067977)--Connection(1910900393)--Thread(Thread[EJB default - 1,5,EJB default])--UPDATE SEQUENCE SET SEQ_COUNT = SEQ_COUNT + ? WHERE SEQ_NAME = ?
bind => [50, TABLE_SEQ]
[EL Finest]: query: 2014-04-26 18:05:14.331--ClientSession(1096067977)--Thread(Thread[EJB default - 1,5,EJB default])--Execute query ValueReadQuery(name="TABLE_SEQ" sql="SELECT SEQ_COUNT FROM SEQUENCE WHERE SEQ_NAME = ?")
[EL Fine]: sql: 2014-04-26 18:05:14.332--ClientSession(1096067977)--Connection(1910900393)--Thread(Thread[EJB default - 1,5,EJB default])--SELECT SEQ_COUNT FROM SEQUENCE WHERE SEQ_NAME = ?
bind => [TABLE_SEQ]
[EL Finest]: sequencing: 2014-04-26 18:05:14.334--ClientSession(1096067977)--Connection(1910900393)--Thread(Thread[EJB default - 1,5,EJB default])--local sequencing preallocation for TABLE_SEQ: objects: 50 , first: 51, last: 100
[EL Finest]: connection: 2014-04-26 18:05:14.335--ServerSession(320769650)--Connection(265370795)--Thread(Thread[EJB default - 1,5,EJB default])--Connection released to connection pool [default].
[EL Finest]: sequencing: 2014-04-26 18:05:14.336--UnitOfWork(698749338)--Thread(Thread[EJB default - 1,5,EJB default])--assign sequence to the object (51 -> jpa.test.model.Student#59887d29)
[EL Finest]: transaction: 2014-04-26 18:05:14.337--UnitOfWork(698749338)--Thread(Thread[EJB default - 1,5,EJB default])--persist() operation called on: jpa.test.model.Student#20f5e794.
[EL Finest]: connection: 2014-04-26 18:05:14.338--ServerSession(320769650)--Connection(1882633843)--Thread(Thread[EJB default - 1,5,EJB default])--Connection acquired from connection pool [default].
[EL Finest]: query: 2014-04-26 18:05:14.338--ClientSession(1096067977)--Thread(Thread[EJB default - 1,5,EJB default])--Execute query DataModifyQuery(name="TABLE_SEQ" sql="UPDATE SEQUENCE SET SEQ_COUNT = SEQ_COUNT + ? WHERE SEQ_NAME = ?")
[EL Finest]: connection: 2014-04-26 18:05:14.339--ClientSession(1096067977)--Thread(Thread[EJB default - 1,5,EJB default])--reconnecting to external connection pool
[EL Fine]: sql: 2014-04-26 18:05:14.34--ClientSession(1096067977)--Connection(402944403)--Thread(Thread[EJB default - 1,5,EJB default])--UPDATE SEQUENCE SET SEQ_COUNT = SEQ_COUNT + ? WHERE SEQ_NAME = ?
bind => [50, TABLE_SEQ]
[EL Finest]: query: 2014-04-26 18:05:14.342--ClientSession(1096067977)--Thread(Thread[EJB default - 1,5,EJB default])--Execute query ValueReadQuery(name="TABLE_SEQ" sql="SELECT SEQ_COUNT FROM SEQUENCE WHERE SEQ_NAME = ?")
[EL Fine]: sql: 2014-04-26 18:05:14.343--ClientSession(1096067977)--Connection(402944403)--Thread(Thread[EJB default - 1,5,EJB default])--SELECT SEQ_COUNT FROM SEQUENCE WHERE SEQ_NAME = ?
bind => [TABLE_SEQ]
[EL Finest]: sequencing: 2014-04-26 18:05:14.345--ClientSession(1096067977)--Connection(402944403)--Thread(Thread[EJB default - 1,5,EJB default])--local sequencing preallocation for TABLE_SEQ: objects: 50 , first: 101, last: 150
[EL Finest]: connection: 2014-04-26 18:05:14.346--ServerSession(320769650)--Connection(1882633843)--Thread(Thread[EJB default - 1,5,EJB default])--Connection released to connection pool [default].
[EL Finest]: sequencing: 2014-04-26 18:05:14.347--UnitOfWork(698749338)--Thread(Thread[EJB default - 1,5,EJB default])--assign sequence to the object (101 -> jpa.test.model.Student#20f5e794)
[EL Finer]: transaction: 2014-04-26 18:05:14.348--UnitOfWork(698749338)--Thread(Thread[EJB default - 1,5,EJB default])--begin unit of work flush
[EL Finest]: query: 2014-04-26 18:05:14.351--UnitOfWork(698749338)--Thread(Thread[EJB default - 1,5,EJB default])--Execute query InsertObjectQuery(jpa.test.model.Student#59887d29)
[EL Finest]: connection: 2014-04-26 18:05:14.353--ServerSession(320769650)--Connection(1582457600)--Thread(Thread[EJB default - 1,5,EJB default])--Connection acquired from connection pool [default].
[EL Finest]: connection: 2014-04-26 18:05:14.354--ClientSession(1096067977)--Thread(Thread[EJB default - 1,5,EJB default])--reconnecting to external connection pool
[EL Fine]: sql: 2014-04-26 18:05:14.354--ClientSession(1096067977)--Connection(1927398752)--Thread(Thread[EJB default - 1,5,EJB default])--INSERT INTO STUDENTS (ID_STUDENT, NAME) VALUES (?, ?)
bind => [51, Paolo]
[EL Finest]: query: 2014-04-26 18:05:14.37--UnitOfWork(698749338)--Thread(Thread[EJB default - 1,5,EJB default])--Execute query InsertObjectQuery(jpa.test.model.Student#55cdaad2)
[EL Fine]: sql: 2014-04-26 18:05:14.371--ClientSession(1096067977)--Connection(1927398752)--Thread(Thread[EJB default - 1,5,EJB default])--INSERT INTO STUDENTS (ID_STUDENT, NAME) VALUES (?, ?)
bind => [1, Anna]
[EL Finest]: query: 2014-04-26 18:05:14.373--UnitOfWork(698749338)--Thread(Thread[EJB default - 1,5,EJB default])--Execute query InsertObjectQuery(jpa.test.model.Student#20f5e794)
[EL Fine]: sql: 2014-04-26 18:05:14.373--ClientSession(1096067977)--Connection(1927398752)--Thread(Thread[EJB default - 1,5,EJB default])--INSERT INTO STUDENTS (ID_STUDENT, NAME) VALUES (?, ?)
bind => [101, Luigi]
[EL Finer]: transaction: 2014-04-26 18:05:14.375--UnitOfWork(698749338)--Thread(Thread[EJB default - 1,5,EJB default])--end unit of work flush
[EL Finer]: transaction: 2014-04-26 18:05:14.376--UnitOfWork(698749338)--Thread(Thread[EJB default - 1,5,EJB default])--resume unit of work
Exiting org.jboss.invocation.InterceptorContext$Invocation.insertStudent
Business method insertStudent in org.jboss.invocation.InterceptorContext$Invocation takes 5878 ms to execute
18:05:14,409 INFO [org.jboss.as.naming] (Remoting "pc" task-1) JBAS011806: Channel end notification received, closing channel Channel ID 03cefe33 (inbound) of Remoting connection 3138554d to /127.0.0.1:65303

Answer 1

Problem solved.
In order to work well with EclipseLink transactions, is must specify (in the persistence.xml file) which server we are using, in my case:
<property name="eclipselink.target-server" value="JBoss"/>