Hibernate trouble: INSERT instead of UPDATE when using Inheritance:SINGLE_TABLE and SecondaryTables

问题

I have implemented inheritance hierarchy using SINGLE_TABLE with SecondaryTables.

This works otherwise, but when my secondary table's field(s) are empty (= null in Oracle), next update to the entity fails since Hibernate thinks it should INSERT to the table when it should UPDATE. Example:

CREATE TABLE TASK 
(
   ID NUMBER(10) NOT NULL 
   , TYPE NUMBER(1) NOT NULL 
   , STATUS NUMBER(1) NOT NULL 
, CONSTRAINT TASK_PK PRIMARY KEY  (ID) ENABLE);

CREATE TABLE SUB_TASK 
(
  ID NUMBER(10) NOT NULL 
, TEXT VARCHAR2(4000 CHAR) 
, CONSTRAINT SUB_TASK_PK PRIMARY KEY 
(ID) ENABLE);

ALTER TABLE SUB_TASK
ADD CONSTRAINT SUB_TASK_FK1 FOREIGN KEY
(ID)REFERENCES TASK(ID)ENABLE;

Task.java:

@Entity
@Table(name="TASK")
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name="TYPE",discriminatorType=DiscriminatorType.INTEGER)
public abstract class Task implements Serializable, Comparable<Task> {

@Id
@Column(nullable = false)
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "TASK_GEN")
@SequenceGenerator(name = "TASK_GEN", sequenceName = "SEQ_TASK", allocationSize = 1)
private Long id;

@Column(name = "TYPE", nullable = false, insertable=false, updatable=false)
private int typeCode;

SubTask.java

@Entity
@DiscriminatorValue("7")
@SecondaryTable(name = "SUB_TASK", pkJoinColumns = {@PrimaryKeyJoinColumn(name = "id", referencedColumnName = "id")})
public class SubTask extends Task implements Serializable {

@Column(name="TEXT", length = 4000, table="SUB_TASK")
@Size(max = 4000)
private String text;

public String getText() {
    return text;
}

public void setText(String text) {
    this.text = text;
}

}

Exception when saving an entity which previously had null SubTask.text:

Caused by: org.hibernate.exception.ConstraintViolationException: ORA-00001: yksikäsitteistä rajoitetta (SUB_TASK_PK) loukattu

at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:128)
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:125)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:110)
at org.hibernate.engine.jdbc.internal.proxy.AbstractStatementProxyHandler.continueInvocation(AbstractStatementProxyHandler.java:129)
at org.hibernate.engine.jdbc.internal.proxy.AbstractProxyHandler.invoke(AbstractProxyHandler.java:81)
at $Proxy75.executeUpdate(Unknown Source)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2965)
at org.hibernate.persister.entity.AbstractEntityPersister.updateOrInsert(AbstractEntityPersister.java:3028)
at org.hibernate.persister.entity.AbstractEntityPersister.update(AbstractEntityPersister.java:3350)
at org.hibernate.action.internal.EntityUpdateAction.execute(EntityUpdateAction.java:140)

I debugged relevant Hibernate code, AbstractEntityPersister.java:

    if ( !isInverseTable( j ) ) {

        final boolean isRowToUpdate;
        if ( isNullableTable( j ) && oldFields != null && isAllNull( oldFields, j ) ) {
            //don't bother trying to update, we know there is no row there yet
            isRowToUpdate = false;
        }
        else if ( isNullableTable( j ) && isAllNull( fields, j ) ) {
            //if all fields are null, we might need to delete existing row
            isRowToUpdate = true;
            delete( id, oldVersion, j, object, getSQLDeleteStrings()[j], session, null );
        }
        else {
            //there is probably a row there, so try to update
            //if no rows were updated, we will find out
            isRowToUpdate = update( id, fields, oldFields, rowId, includeProperty, j, oldVersion, object, sql, session );
        }

        if ( !isRowToUpdate && !isAllNull( fields, j ) ) {
            // assume that the row was not there since it previously had only null
            // values, so do an INSERT instead
            //TODO: does not respect dynamic-insert
            insert( id, fields, getPropertyInsertability(), j, getSQLInsertStrings()[j], object, session );
        }

    }

and it looks like the first if ("don't bother trying to update") is done and isRowToUpdate = false, and the last if (if ( !isRowToUpdate && !isAllNull( fields, j ) ) is also done, so that insert is executed.

I guess I could get around this by adding a dummy non-null field to table SUB_TASK, but is this my only choice?

Using Hibernate 4.17.final

EDIT: to hopefully clarity what I am doing:

SubTask s = taskRepository.findOne(42l);
s.setText("dasdsa");
taskRepository.save(s); // OK
s.setText(null); 
taskRepository.save(s); // OK
s.setText("update after null value");
taskRepository.save(s); // exception 

I use Spring Data for persistence, but it does not look like problem is related to it (and I would assume same thing happens when using vanilla JPA)

回答1:

I had a somewhat similar problem, with a @ManyToOne relationship defined in a secondary table. When the secondary table had a row referring to the entity in the primary table, the relationship column was null and trying to set a value, Hibernate tried to insert a new row instead of updating the existing one, throwing a constraint violation exception.

The solution was to use the annotation @org.hibernate.annotations.Table(appliesTo="secondary_table", optional=false), which makes Hibernate to update the row.

I´m not sure about the behaviour when the row in the secondary table doesn´t exist, but perhaps it solves your problem.

回答2:

Using @dampudia solution worked for me.

Please make sure to add the following on the primary table and not the secondary table. Also, please note @Table annotation used here is from hibernate and not java.persistence.

@org.hibernate.annotations.Table(appliesTo="secondary_table", optional=false)

来源：https://stackoverflow.com/questions/14683592/hibernate-trouble-insert-instead-of-update-when-using-inheritancesingle-table