= Hibernate 6.5.0.Final
Steve Ebersole
:awestruct-tags: ["Hibernate ORM", "Releases"]
:awestruct-layout: blog-post

:family: 6.5

:docs-url: https://docs.jboss.org/hibernate/orm/{family}
:javadocs-url: {docs-url}/javadocs
:migration-guide-url: {docs-url}/migration-guide/migration-guide.html
:intro-guide-url: {docs-url}/introduction/html_single/Hibernate_Introduction.html
:user-guide-url: {docs-url}/userguide/html_single/Hibernate_User_Guide.html
:ql-guide-url: {docs-url}/querylanguage/html_single/Hibernate_Query_Language.html

6.5 has gone final!


[[java-time]]
== Java Time Handling

Java Time objects can now be directly marshalled through the JDBC driver as defined by JDBC 4.2.
In previous versions, Hibernate would handle Java Time objects using `java.sql.Date`, `java.sql.Time` or
`java.sql.Timestamp` references as intermediate forms.

Another behavioral change with this is handling for timezones.  `OffsetDateTime`, `OffsetTime` and
`ZonedDateTime` all encode explicit timezone information.  With direct marshalling, Hibernate simply
passes along the value as-is.  In the legacy behavior, since the `java.sql` variants do not
encode timezone information, Hibernate generally has to specially handle timezones when converting to
those intermediate forms.

For 6.5 this behavior is disabled by default.  To opt-in,

[source,properties]
----
hibernate.type.java_time_use_direct_jdbc=true
----

See the link:{javadocs-url}/org/hibernate/cfg/MappingSettings.html#PREFER_JAVA_TYPE_JDBC_TYPES[setting Javadoc] for additional details.


IMPORTANT: This feature is known to not work with the Sybase jConnect driver despite
this feature being part of JDBC since 4.2 (Java 8).  We have notified the Sybase development team, but this seems unlikely to change.


[[query-cache-layout]]
== Configurable Query Cache Layout

In Hibernate ORM 6.0 the query cache layout changed from a "shallow" representation of entities and collections,
to a "full" representation. This was done to support re-materializing join fetched data from the query cache data
without hitting the database.  Storing the full data in the query cache leads to a higher memory consumption,
which in turn might also hurt application throughput due to a higher garbage collection activity.

6.5 adds the ability to configure the format in which query results are stored in the query cache, either

* globally via the `hibernate.cache.query_cache_layout` setting
* per entity or collection via the `@QueryCacheLayout` annotation

The global `hibernate.cache.query_cache_layout` setting defaults to the `AUTO` value,
which will automatically choose `SHALLOW` or `FULL` for an entity/collection,
depending on whether the entity/collection is cacheable.

Applications that want to retain the `FULL` cache layout that Hibernate ORM 6.0 used should configure
the global property `hibernate.cache.query_cache_layout=FULL`.
Applications that want the cache layout that Hibernate ORM 5 and older versions used should configure
the global property `hibernate.cache.query_cache_layout=SHALLOW`.

[NOTE]
====
Even with the `SHALLOW` cache layout, the association eagerness implied through join fetches will be respected,
and associations will be eagerly initialized. So there is no change of behavior when choosing a different cache layout.

With `SHALLOW`, Hibernate might need to hit the database to materialize the associated data *if it does not exist in the second level cache*.
====

[[record-as-idclass]]
== Allow Java record as @IdClass

A Java record can now be used as an `@IdClass`

[source,java]
----
record PK(Integer key1, Integer key2) {}

@Entity
@IdClass(PK.class)
class AnEntity {
	@Id Integer key1;
	@Id Integer key2;
	...
}
----

[[auto-filters]]
== Support for Auto Enabled Filters

Filters can now be automatically enabled for each Session and StatelessSession

[source,java]
----
@FilterDef(
    name="active-filter",
    condition="status = true",
    autoEnabled=true
)
@Filter(name="active-filter")
@Entity
class DeletableEntity {
    ...
}
----

Can be combined with the ability to dynamically resolve condition parameters, e.g.

[source,java]
----
class TenantIdResolver implements Supplier<String> {
    @Override
    public String get() {
        return SomeContext.determineTenantId();
    }
}

@FilterDef(
    name="tenancy-filter",
    condition="tenant_id = :tenantId",
    autoEnabled=true,
    parameter = @ParamDef(
        name="tenantId",
        type=String.class,
        resolver=TenantIdResolver.class
    )
)
@Filter(name="tenancy-filter")
@Entity
class SensitiveData {
	...
}
----


[[sqm-mutation-joins]]
== Joined Mutation Queries

UPDATE and DELETE queries can now use joins, e.g.

[source]
----
delete from Person p where p.association.someAttr = 1
----


[[manually-assigned-generated-ids]]
== Manually Assigned Identifiers with custom `Generator`

Manually assigned identifier values can now be used with custom a `Generator` thanks to the new `allowAssignedIdentifiers()` method.

[source,java]
----
class MyIdGenerator implements Generator {
    ...
    @Override public boolean allowAssignedIdentifiers() {
        return true;
    }
}

@IdGeneratorType(MyIdGenerator.class)
@Target({METHOD, FIELD})
@Retention(RUNTIME)
@interface MyGeneratedId {
}

@Entity
class Book {
  @Id @MyGeneratedId
  Integer id;
  ...
}

Book book = new Book(1,...)
session.persist(book);
----



[[query-result-count]]
== SelectionQuery.getResultCount()

Selection queries now have the ability to report the number of results there will
be in the final result.

IMPORTANT: This triggers a query against the database.

[source,java]
----
Query query = session.createQuery("from Person");
int results = query.getResultCount();
----

[[key-pagination]]
== Key-based Pagination

As an incubating feature, 6.5 offers support for link:{intro-guide-url}#key-based-pagination[key-based pagination] (sometimes called "keyset" pagination) via both `SelectionQuery` and link:{intro-guide-url}#key-based-paging[generated query methods].

Please see the Javadoc for link:{javadocs-url}/org/hibernate/query/KeyedPage.html[`KeyedPage`] and link:{javadocs-url}/org/hibernate/query/KeyedResultList.html[`KeyedResultList`] for more information.

[[on-conflict]]
== ON CONFLICT Clause for Insert Queries

Both HQL and Criteria now support an optional ON CONFLICT clause to allow controlling what
should happen when a constraint violation occurs, e.g.

[source]
----
insert into Person (id, name)
values (1, 'John')
on conflict do nothing
----

See the link:{user-guide-url}#hql-insert[User Guide] for more details.


[[stateless-session]]
== Work on StatelessSession

`StatelessSession` now supports https://hibernate.atlassian.net/browse/HHH-17620[filters] and https://hibernate.atlassian.net/browse/HHH-17673[SQL logging]


[[jakarta-data]]
== Jakarta Data

6.5 also includes a tech preview of Jakarta Data based on the Hibernate annotation processor.