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Hibernate 6.5.0.CR2

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6.5 brings many new features, in addition to many improvements and fixes.

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,

hibernate.type.java_time_use_direct_jdbc=true

See the setting Javadoc for additional details.

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.

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.

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.

Allow Java record as @IdClass

A Java record can now be used as an @IdClass

record PK(Integer key1, Integer key2) {}

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

Support for Auto Enabled Filters

Filters can now be automatically enabled for each Session and StatelessSession

@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.

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 {
        ...
}

Joined Mutation Queries

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

delete from Person p where p.association.someAttr = 1

Manually Assigned Identifiers with custom Generator

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

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);

SelectionQuery.getResultCount()

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

This triggers a query against the database. 
Query query = session.createQuery("from Person");
int results = query.getResultCount();

Key-based Pagination

As an incubating feature, 6.5 offers support for key-based pagination (sometimes called "keyset" pagination) via both SelectionQuery and generated query methods.

Please see the Javadoc for KeyedPage and KeyedResultList for more information.

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.

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

See the User Guide for more details.

Work on StatelessSession

StatelessSession now supports filters and SQL logging

Jakarta Data

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

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