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7.0 Migration Guide

Table of Contents

This guide discusses migration to Hibernate ORM version 7.0. For migration from earlier versions, see any other pertinent migration guides as well.

Apache License

Starting with 7.0, Hibernate ORM will be licensed under the Apache License 2.0.

Note
 While the Hibernate team still believes that our long published interpretation of LGPL to be compatible with ASL and similar licenses, enough FUD has been spread about it to be considered a lost cause in terms of inclusion in various projects. At this point, it just makes sense to change - it opens up wider acceptance amongst Apache/Jakarta projects and others.

As part of this effort, the Hibernate team reached out to the authors of "non-trivial" contributions to request permission to relicense their work under the Apache License. The response was overwhelming positive, although we never heard back from some contributors and another explicitly disagreed. This required a few actions on our part:

Requirements

Java 17

Hibernate now baselines on Java 17. Newer Java versions may also be used.

Jakarta Persistence 3.2

7.0 migrates to Jakarta Persistence 3.2 which is fairly disruptive, mainly around:

  • Type parameters:

    • Affects much of the Criteria API - especially roots, joins, paths

    • Affects much of the Entity Graph API - see org.hibernate.graph Package for details.

  • New JPA features colliding with previous Hibernate extension features:

    • Nulls (JPA) v. NullPrecedence (Hibernate), including JPA’s new Order#getNullPrecedence() returning Nulls colliding with Hibernate’s SqmSortSpecification#getNullPrecedence returning NullPrecedence. Hibernate’s form was renamed to SqmSortSpecification#getHibernateNullPrecedence to avoid the collision.

    • SchemaManager is now also a JPA contract exposed as EntityManagerFactory#getSchemaManager which leads to type issues for Hibernate’s SessionFactory#getSchemaManager. Hibernate’s SchemaManager now extends the new JPA SchemaManager. But that is a bytecode incompatibility.

    • JPA has added support in its Graph API for things Hibernate has supported for some time. Some of those are collisions requiring changes to the Hibernate API.

    • Transaction#getTimeout. JPA 3.2 adds #getTimeout but uses Integer whereas Hibernate has historically used int. Note that this raises the possibility of a NullPointerException during migration if, e.g., performing direct comparisons on the timeout value against an in (auto unboxing).

See this blog post for a good discussion of the changes in Jakarta Persistence 3.2.

Hibernate Models

For many years Hibernate has used the Hibernate Commons Annotations (HCANN) library for handling various low-level tasks related to understanding the structure of an application domain model, reading annotations and weaving in XML mapping documents.

However, HCANN suffers from a number of limitations that continued to be problematic. And given the use of HCANN across multiple projects, doing the needed refactoring was simply not possible.

The Hibernate Models project was developed to be a better alternative to HCANN. Hibernate Models is essentially an abstraction over reflection (Type, Class, Member, …​) and annotations. Check out its project page for complete details.

7.0 uses Hibernate Models in place of HCANN.

New Features

See the website for the list of new features in the 7.0 series.

Changes to API

This section describes changes to contracts (classes, interfaces, methods, etc.) which are consider API.

Defer to JPA

A general theme in 7.0 has been to remove Hibernate-specific features that have a direct replacement in JPA.

Session#load

Session#load methods have been removed in favor of Session#getReference which have the same semantic.

Session#get

Session#get methods were deprecated in favor of the JPA-standard Session#find, and new overloads of Session#find were added.

Note
 Session#get was not previously deprecated as Session#load was, so it was not appropriate to remove it.

Session#refresh

The forms of Session#refresh accepting an entity-name have been removed; the passed entity already indicates the entity-name (even with dynamic models).

Session#refresh(String entityName, Object object)

Removed in favor of Session#refresh(Object object)

Session#refresh(String entityName, Object object, LockOptions lockOptions)

Removed in favor of Session#refresh(Object object, LockOptions lockOptions)

Session#save, Session#update, Session#saveOrUpdate

All forms of Session#save, Session#update, Session#saveOrUpdate have been removed. See the discussion at Session flush and persist.

Session#save

Removed in favor of Session#persist.

Session#update

Removed in favor of Session#merge

Session#saveOrUpdate

Removed in favor #persist if the entity is transient or #merge if the entity is detached

Relatedly, org.hibernate.annotations.CascadeType#SAVE_UPDATE has been removed in favor of org.hibernate.annotations.CascadeType#PERSIST and/or org.hibernate.annotations.CascadeType#MERGE[1]

Session#delete

Session#delete methods has been removed in favor of Session#remove. Relatedly, org.hibernate.annotations.CascadeType#DELETE was removed in favor of org.hibernate.annotations.CascadeType#REMOVE[1]

org.hibernate.graph Package

The EntityGraph API was enhanced in JPA 3.2, and made much more useful. The incubating package org.hibernate.graph contains extensions to that API, which have been significantly impacted by the migration to JPA 3.2, and by the addition of new functionality. Furthermore, some legacy operations were declared with incorrect generic type signatures (by both JPA, and by Hibernate).

This package has been significantly re-engineered, and the impact of this effort includes:

  • some breaking changes to type signatures, and

  • a number of deprecations of legacy operations which are now covered by JPA.

Also, a key subgraph now always refers to a Map key, and never to an entity id.

We encourage migration to the use of the new JPA-standard operations.

Or, alternatively, when building graphs, consider Hibernate’s support for textual graph parsing. See also [NamedEntityGraph].

Annotations

  • Removed @Persister

  • Removed @Proxy - see Replace @Proxy

  • Removed @SelectBeforeUpdate - see Session flush and persist

  • Removed @DynamicInsert#value and @DynamicUpdate#value - usage indicates true

  • Removed @Loader

  • Removed @Table → use JPA @Table

  • Removed @Where and @WhereJoinTable → use @SQLRestriction or @SQLJoinTableRestriction

  • Removed @OrderBy → use @SQLOrder or JPA @OrderBy

  • Removed @ForeignKey → use JPA @ForeignKey

  • Removed @Index → use JPA @Index

  • Removed @IndexColumn → use JPA @OrderColumn

  • Removed @GeneratorType (and GenerationTime, etc)

  • Removed @LazyToOne

  • Removed @LazyCollection

  • Replaced uses of CacheModeType with CacheMode

  • Removed @Cache#include → use @Cache#includeLazy

  • Removed @TestForIssue (for testing purposes) → use org.hibernate.testing.orm.junit.JiraKey or org.hibernate.testing.orm.junit.JiraKeyGroup

Replace @Proxy

Applications will need to replace usages of the removed @Proxy annotation.

@Proxy#proxyClass has no direct replacement, but was also never needed/useful.

Here we focus on @Proxy#lazy attribute which, again, was hardly ever useful. By default (true), Hibernate would proxy an entity when possible and when asked for. "Asked for" includes calls to Session#getReference and lazy associations. All such cases though are already controllable by the application.

  • Instead of Session#getReference, use Session#find

  • Use eager association fetching, for example,

    • FetchType.EAGER (the default for to-one associations anyway), possibly combined with @Fetch,

    • EntityGraph, or a

    • @FetchProfile.

The effect can also often be mitigated using Hibernate’s bytecode-based laziness (possibly combined with @ConcreteProxy).

JDBC exception interpretation

Hibernate now does a better and more consistent job of interpreting database-specific error codes in JDBCExceptions and translating to subtypes of PersistenceException. In particular, interpretation of integrity constraint violations was improved significantly.

Also, LockAcquisitionException now extends PessimisticLockException.

Miscellaneous

  • Removed org.hibernate.Metamodel in favor of org.hibernate.metamodel.model.domain.JpaMetamodel

  • Removed SqmQualifiedJoin - all joins are qualified.

  • Both NaturalIdLoadAccess#using(Map) and NaturalIdMultiLoadAccess#compoundValue() have been removed in favor of Map#of()

  • Removed Session.LockRequest - use LockOptions instead

  • SessionFactory.createEntityManager() now returns Session for convenience

  • CommonQueryContract.setFlushMode() was deprecated in favor of setQueryFlushMode accepting a QueryFlushMode

Changes to SPI

This section describes changes to contracts (classes, interfaces, methods, etc.) which are consider SPI.

Configurable generators

The signature of the Configurable#configure method changed from accepting just a ServiceRegistry instance to the new GeneratorCreationContext interface, which exposes a lot more useful information when configuring the generator itself. The old signature has been deprecated for removal, so you should migrate any custom Configurable generator implementation to the new one. Or better yet, consider migrating to @IdGeneratorType.

Integrator

The previously deprecated method org.hibernate.integrator.spi.Integrator#integrate(Metadata,SessionFactoryImplementor,SessionFactoryServiceRegistry) have been removed in favor of its replacement org.hibernate.integrator.spi.Integrator#integrate(Metadata,BootstrapContext,SessionFactoryImplementor)

Interceptor

Quite a few (again, previously deprecated) methods on Interceptor have been removed in favor of their replacement. This mainly deals with the change in expected Java type of identifiers (done in 6.0) from Serializable to Object.

  • Interceptor#onLoad

  • Interceptor#onFlushDirty

  • Interceptor#onSave

  • Interceptor#onDelete

  • Interceptor#onCollectionRecreate

  • Interceptor#onCollectionRemove

  • Interceptor#onCollectionUpdate

  • Interceptor#findDirty

  • Interceptor#getEntity

Additionally, EmptyInterceptor was removed. As org.hibernate.Interceptor now uses default methods, one can simply implement Interceptor to the same end.

Changes to UserType and CompositeUserType

The API interfaces UserType and CompositeUserType leaked the SPI types SharedSessionContractImplementor and SessionFactoryImplementor, which was a layer-breaker.

The solution was to change the signature of nullSafeSet() and nullSafeGet() in UserType via deprecation of the previous declarations, and remove some unnecessary parameters from methods of the incubating interface CompositeUserType.

JFR SPI

The types EventMonitor and DiagonosticEvent replace the now-deprecated SPIs EventManager and HibernateMonitoringEvent use for integration with Java Flight Recorder.

Hibernate now reports many more kinds of DiagnosticEvent to JFR.

Miscellaneous

  • org.hibernate.metamodel.spi.MetamodelImplementor was removed in favor of org.hibernate.metamodel.MappingMetmodel or org.hibernate.metamodel.model.domain.JpaMetamodel

  • Removed AdditionalJaxbMappingProducer in favor of AdditionalMappingContributor.

  • Removed MetadataContributor in favor of AdditionalMappingContributor

Changes in Behavior

Domain Model Validations

7.0 adds many more checks about illegal use of annotations.

PersistentAttributeType

As of 7.0, Hibernate applies much better validation of an attribute specifying multiple PersistentAttributeTypes. Jakarta Persistence 3.2 has clarified this in the specification. E.g., the following examples are all now illegal -

@Basic
@ManyToOne
private Employee manager;

or

@Lob
@ManyToOne
private Employee manager;

Misplaced Annotations

7.0 does much more in-depth checking that annotations appear in the proper place. While previous versions did not necessarily throw errors, in most cases these annotations were simply ignored.

For example, this code now results in an error:

@Entity
class Book {
    // specifies FIELD access, properties should not be annotated
    @Id
    Integer id;

    // previously ignored, this is an error now
    @Column(name="category")
    String getType() { ... }
}

Identifier Generators

Starting in 7.0 it is no longer valid to combine GenerationType#SEQUENCE with anything other than @SequenceGenerator nor GenerationType#TABLE with anything other than @TableGenerator. Previous versions did not validate this particularly well.

JavaBean Conventions

Previous versions allowed some questionable (at best) attribute naming patterns. For example, this property declaration is no longer allowed:

@Basic
String isDefault();

Disallowed Converters

JPA AttributeConverters are incompatible with the annotations @Id, @Version, @Enumerated, @Embedded, @Temporal and all association-mapping annotations. Previously, any converter applied to an attribute with an incompatible annotation was simply ignored. Hibernate now reports an error in this situation.

This includes auto-applied converters. To suppress the error for an auto-applied converter, use @Convert(disableConversion=true).

StatelessSession Behavior

The behavior of Hibernate’s StatelessSession has changed in 2 specific ways to be aware of:

StatelessSession and Second-Level Cache

A stateless session now makes use of the second-level cache by default. This will affect migrating applications using second-level cache and StatelessSession.

To completely bypass the second-level cache, recovering the previous behavior, call setCacheMode(CacheMode.IGNORE).

It’s often important to explicitly disable puts to the second-level cache in code which performs bulk processing. Set the cache mode to GET or configure jakarta.persistence.cache.storeMode to BYPASS.

StatelessSession and JDBC Batching

The configuration property hibernate.jdbc.batch_size now has no effect on a StatelessSession. JDBC batching may be enabled by explicitly calling setJdbcBatchSize(). However, the preferred approach is to use the new explicit batch operations via insertMultiple(), updateMultiple(), or deleteMultiple().

Query with Implicit SELECT and No Explicit Result Type

In previous versions, Hibernate allowed a query with no select list to be passed to the overload of createQuery() with no explicit result type parameter, for example:

List query =
        session.createQuery("from X, Y")
                .getResultList()

or:

List query =
        session.createQuery("from X join y")
                .getResultList()

The select list was inferred based on the from clause.

In Hibernate 6 we decided to deprecate this overload of createQuery(), since:

  • it returns a raw type Query, resulting in compiler warnings in client code,

  • each query result must be explicitly cast from Object to the query result type, and

  • the second query is truly ambiguous, with no obviously intuitive interpretation.

As of Hibernate 7, the method remains deprecated, and potentially-ambiguous queries are no longer accepted. Migration paths include:

  1. explicitly specify the select list,

  2. add X.class or Object[].class as a second argument, to disambiguate the interpretation of the query, or

  3. in the case where the query should return exactly one entity, explicitly assign the alias this to that entity.

For example, the queries above may be migrated via:

List<Object[]> result =
        session.createQuery("from X, Y", Object[].class)
                .getResultList()

or:

List<X> result =
        session.createQuery("from X join y", X.class)
                .getResultList()

Session flush and persist

The removal of CascadeType.SAVE_UPDATE slightly changes the persist and flush behaviour to conform with the Jakarta Persistence specification.

Making a transient entity persistent or flushing a managed entity now results in an jakarta.persistence.EntityExistsException if:

  • the entity has an association with cascade = CascadeType.ALL or cascade = CascadeType.PERSIST, and

  • the association references a detached instance of the associated entity class.

To avoid this exception, the reference to the detached instance should be replaced with a reference to a managed instance associated with the current session. Such a reference may be obtained by calling merge() or getReference() on the detached entity instance.

Consider the following model

@Entity
class Parent {
	...

	@OneToMany(cascade = CascadeType.ALL, mappedBy = "parent", orphanRemoval = true)
	@LazyCollection(value = LazyCollectionOption.EXTRA)
	private Set<Child> children = new HashSet<>();

	public void addChild(Child child) {
		children.add( child );
		child.setParent( this );
	}
}

@Entity
class Child {
	...

	@ManyToOne
	private Parent parent;
}

Assuming we have c1 as a detached Child, the following code will now result in jakarta.persistence.EntityExistsException being thrown at flush time:

Parent parent = session.find( Parent.class, parentId );
parent.addChild( c1 );

Instead, c1 must first be re-associated with the Session using merge:

Parent parent = session.find( Parent.class, parentId );
Child merged = session.merge( c1 );
parent.addChild( merged );

Refreshing/Locking Detached Entities

Traditionally, Hibernate allowed detached entities to be refreshed. However, Jakarta Persistence prohibits this practice and specifies that an IllegalArgumentException should be thrown instead. Hibernate now fully aligns with the JPA specification in this regard.

Along the same line of thought, also acquiring a lock on a detached entity is no longer allowed.

To this effect the hibernate.allow_refresh_detached_entity, which allowed Hibernate’s legacy refresh behaviour to be invoked, has been removed.

Cascading Persistence for @Id and @MapsId Attributes

Previously Hibernate automatically enabled cascade=PERSIST for association fields annotated @Id or @MapsId. This was undocumented and unexpected behavior, and arguably against the intent of the Persistence specification.

Existing code which relies on this behavior should be modified by addition of explicit cascade=PERSIST to the association field.

Temporal Types Returned by Native Queries

In the absence of a @SqlResultSetMapping, previous versions of Hibernate used java.sql types (Date, Time, Timestamp) to represent date/time types returned by a native query. In 7.0, such queries return types defined by java.time (LocalDate, LocalTime, LocalDateTime) by default. The previous behavior may be recovered by setting hibernate.query.native.prefer_jdbc_datetime_types to true.

XML FormatMapper Changes

Previous versions of Hibernate ORM used an undefined/provider-specific format for serialization/deserialization of collections, maps and byte arrays to/from XML, which was not portable.

XML FormatMapper implementations now use a portable format for collections, maps, and byte arrays. This change is necessary to allow mapping basic arrays as SqlTypes.XML_ARRAY.

The migration requires to read data and re-save it.

To retain backwards compatibility, configure the setting hibernate.type.xml_format_mapper.legacy_format to true.

Criteria API and Implicit Treats

It was previously possible to use the string version of the jakarta.persistence.criteria.Path#get and jakarta.persistence.criteria.From#join methods with names of attributes defined in an inheritance subtype of the type represented by the path expression. This was handled internally by implicitly treating the path as the subtype which defines said attribute. Since Hibernate 7.0, aligning with the JPA specification, the Criteria API will no longer allow retrieving subtype attributes this way, and it’s going to require an explicit jakarta.persistence.criteria.CriteriaBuilder#treat to be called on the path first to downcast it to the subtype which defines the attribute.

Implicit treats are still going to be applied when an HQL query dereferences a path belonging to an inheritance subtype.

SessionFactory Name (and JNDI)

Hibernate defines SessionFactory#getName (specified via cfg.xml or hibernate.session_factory_name) which is used to help with (de)serializing a SessionFactory. It is also, unless hibernate.session_factory_name_is_jndi is set to false, used in biding the SessionFactory into JNDI.

This SessionFactory#getName method pre-dates Jakarta Persistence (and JPA). It now implements EntityManagerFactory#getName inherited from Jakarta Persistence, which states that this name should come from the persistence-unit name. To align with Jakarta Persistence (the 3.2 TCK tests this), Hibernate now considers the persistence-unit name if no hibernate.session_factory_name is specified.

However, because hibernate.session_factory_name is also a trigger to attempt to bind the SessionFactory into JNDI, this change to consider persistence-unit name, means that each SessionFactory created through Jakarta Persistence now has a name and Hibernate attempts to bind it to JNDI.

To work around this we have introduced a new hibernate.session_factory_jndi_name setting that can be used to explicitly specify a name for JNDI binding. The new behavior is as follows (assuming hibernate.session_factory_name_is_jndi is not explicitly configured):

  • If hibernate.session_factory_jndi_name is specified, the name is used to bind into JNDI

  • If hibernate.session_factory_name is specified, the name is used to bind into JNDI

Hibernate can use the persistence-unit name for binding into JNDI as well, but hibernate.session_factory_name_is_jndi must be explicitly set to true.

@OrderColumn in Unowned @OneToMany Associations

In an unowned (mappedBy) one-to-many association, an @OrderColumn should, in principle, also be mapped by a field of the associated entity, and the value of the order column should be determined by the value of this field, not by the position in the list.

Previously, since version 4.1, Hibernate would issue superfluous SQL UPDATE statements to set the value of the order column based on the state of the unowned collection. This was incorrect according to the JPA specification, and inconsistent with the natural semantics of Hibernate.

In Hibernate 7, these SQL UPDATE statements only occur if the @OrderColumn is not also mapped by a field of the entity.

ValidationMode#AUTO

Starting in 7.0, when ValidationMode#AUTO is specified and a Bean Validation provider is available but creating the ValidatorFactory results in an exception, that exception is now propagated (re-thrown).

Changes Affecting DDL

This section describes changes which may affect the application’s database schema.

Default Precision for timestamp

The default precision for Oracle timestamps was changed to 9, i.e. nanosecond precision. The default precision for SQL Server timestamps was changed to 7, i.e. 100 nanosecond precision.

Note that these changes only affect DDL generation.

Array Mapping Changes

DB2, SAP HANA, SQL Server and Sybase ASE

On DB2, SAP HANA, SQL Server and Sybase ASE, basic arrays now map to the SqlTypes.XML_ARRAY type code, whereas previously, the dialect mapped arrays to SqlTypes.VARBINARY. The SqlTypes.XML_ARRAY type uses the xml DDL type which enables using arrays in other features through the various XML functions.

The migration requires to read data and re-save it. Note that XML support on Sybase ASE is not enabled by default and requires to run sp_configure 'enable xml', 1.

To retain backwards compatibility, configure the setting hibernate.type.preferred_array_jdbc_type to VARBINARY.

MySQL/MariaDB

On MySQL and MariaDB, basic arrays now map to the SqlTypes.JSON_ARRAY type code, whereas previously, the dialect mapped arrays to SqlTypes.VARBINARY. The SqlTypes.JSON_ARRAY type uses the json DDL type which enables using arrays in other features through the various JSON functions.

The migration requires to read data and re-save it.

To retain backwards compatibility, configure the setting hibernate.type.preferred_array_jdbc_type to VARBINARY.

Default DDL Type for char and Character

Previously, char and Character fields were, by default, mapped to char(1) columns by the schema export tool. However, MySQL treats a char(1) containing a single space as an empty string, resulting in broken behavior for some HQL and SQL functions. Now, varchar(1) is used by default.

Changes Related to Settings

  • Removed hibernate.mapping.precedence and friends

  • Removed hibernate.allow_refresh_detached_entity

Connection Pools

We have decided to drop built-in support for the Vibur, Proxool and UCP Connection Pools for a variety of reasons - the main one being that we are not able to properly test them.

We recommend using Agroal or HikariCP instead. Alternatively, you may implement the ConnectionProvider interface to integrate the connection pool of your choice. In fact, some connection pools already include their own implementations of ConnectionProvider.

1. `org.hibernate.annotations.Cascade` and `org.hibernate.annotations.CascadeType` are both fully deprecated as of 7.0