Does save() in hibernate really issue an insert statement as opposed to persist()?

Question

I tried out a sample program,in which I use the save() method on my entity object for which the identifier has a sequence generated value.But i don't find the save() generating an insert query.Insert query is generated only on transaction commit().Not sure where the issue is.Below are the code details:

Entity class:

@Entity
@org.hibernate.annotations.Entity(dynamicUpdate = true)
@Table(name = "Employee", uniqueConstraints = { @UniqueConstraint(columnNames = "ID"),
        @UniqueConstraint(columnNames = "EMAIL") })
@SequenceGenerator(name="seq", initialValue=1, allocationSize=100)
public class EmployeeEntity implements Serializable {
    @Id
    @Column(name = "ID", unique = true, nullable = false)
    @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="seq")
    private Integer employeeId;
    @Column(name = "EMAIL", unique = true, nullable = false, length = 100)
    private String email;
    @Column(name = "FIRST_NAME", unique = false, nullable = false, length = 100)
    private String firstName;
    @Column(name = "LAST_NAME", unique = false, nullable = false, length = 100)
    private String lastName;

    public Integer getEmployeeId() {
        return employeeId;
    }

    public void setEmployeeId(Integer employeeId) {
        this.employeeId = employeeId;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
}

hibernate configuration file:

<hibernate-configuration>
    <session-factory>
        <property name="hibernate.dialect">org.hibernate.dialect.HSQLDialect</property>
        <property name="hibernate.show_sql">true</property>
        <property name="hibernate.connection.driver_class">org.hsqldb.jdbcDriver</property>
        <property name="hibernate.connection.username">sa</property>
        <property name="hibernate.connection.password"></property>
        <property name="hibernate.connection.url">jdbc:hsqldb:mem:test</property>
        <property name="hibernate.hbm2ddl.auto">create</property>
        <mapping class="com.test.hibernate.entity.EmployeeEntity"></mapping>
        </session-factory>
</hibernate-configuration>

The method from which i invoke save:

public static void checkSave_Persist(){
        Session session = HibernateUtil.getSessionFactory().openSession();
        System.out.println("Default flush mode:" + session.getFlushMode());
        session.beginTransaction();     

        EmployeeEntity emp = new EmployeeEntity();
        emp.setEmail("demo-user@mail.com");
        emp.setFirstName("demo");
        emp.setLastName("user");
        Integer empTest =(Integer)session.save(emp);

        session.getTransaction().commit(); //insert query is generated only at this point
        session.close();
        HibernateUtil.shutdown();
    }

On execution of Integer empTest =(Integer)session.save(emp);, below is the generated log:(no insert query)

14:16:11,113 TRACE DefaultSaveOrUpdateEventListener:180 - Saving transient instance
14:16:11,129 DEBUG SQL:109 - call next value for hibernate_sequence
Hibernate: call next value for hibernate_sequence
14:16:11,149 TRACE JdbcCoordinatorImpl:371 - Registering statement [org.hsqldb.jdbc.jdbcPreparedStatement@75bf0a2[sql=[call next value for hibernate_sequence]]]
14:16:11,153 TRACE JdbcCoordinatorImpl:437 - Registering result set [org.hsqldb.jdbc.jdbcResultSet@2c231468]
14:16:11,153 DEBUG SequenceGenerator:127 - Sequence identifier generated: BasicHolder[java.lang.Integer[1]]
14:16:11,169 TRACE JdbcCoordinatorImpl:455 - Releasing result set [org.hsqldb.jdbc.jdbcResultSet@2c231468]
14:16:11,169 TRACE JdbcCoordinatorImpl:573 - Closing result set [org.hsqldb.jdbc.jdbcResultSet@2c231468]
14:16:11,169 TRACE JdbcCoordinatorImpl:412 - Releasing statement [org.hsqldb.jdbc.jdbcPreparedStatement@75bf0a2[sql=[call next value for hibernate_sequence]]]
14:16:11,169 TRACE JdbcCoordinatorImpl:525 - Closing prepared statement [org.hsqldb.jdbc.jdbcPreparedStatement@75bf0a2[sql=[call next value for hibernate_sequence]]]
14:16:11,185 TRACE JdbcCoordinatorImpl:278 - Starting after statement execution processing [ON_CLOSE]
14:16:11,185 DEBUG AbstractSaveEventListener:130 - Generated identifier: 100, using strategy: org.hibernate.id.SequenceHiLoGenerator
14:16:11,185 TRACE AbstractSaveEventListener:169 - Saving [com.test.hibernate.entity.EmployeeEntity#100]
14:16:11,216 TRACE ActionQueue:165 - Adding an EntityInsertAction for [com.test.hibernate.entity.EmployeeEntity] object
14:16:11,231 TRACE ActionQueue:178 - Adding insert with no non-nullable, transient entities: [EntityInsertAction[com.test.hibernate.entity.EmployeeEntity#100]]
14:16:11,231 TRACE ActionQueue:198 - Adding resolved non-early insert action.
14:16:11,231 TRACE UnresolvedEntityInsertActions:213 - No unresolved entity inserts that depended on [[com.test.hibernate.entity.EmployeeEntity#100]]
14:16:11,247 TRACE UnresolvedEntityInsertActions:122 - No entity insert actions have non-nullable, transient entity dependencies.

I am not explicitly setting the ID column but using the sequence to generate the ID.

Answer 1

That's the normal usage of a transaction, where you queue all your statements.

The insert statement is only issued at commit, and if something happened (usually returns an HibernateException), you can undo all the operations with a rollback().