HHH-10043 - Migration Guide
This commit is contained in:
Steve Ebersole
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= 5.0 Migration Guide
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:toc:
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This guide discusses migration from Hibernate ORM version 4.3 to version 5.0. For migration from
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earlier versions, see any other pertinent migration guides as well.
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* Re-purposing of Configuration. Configuration, historically, allowed users to iteratively add
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settings and mappings in any order and to query the state of settings and mapping information in the middle
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of that process. Which meant that building the mapping information could not effectively rely on any settings
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being available. This lead to many limitations and problems. Quite a few methods have been removed from
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Configuration. todo : topical guide on bootstrapping, reference that here.
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* Migrated `org.hibernate.metamodel.spi.TypeContributor` and `org.hibernate.metamodel.spi.TypeContributions`
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to `org.hibernate.boot.model.TypeContributor` and `org.hibernate.boot.model.TypeContributions`
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* Naming strategies - discuss split.
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* implicit column names, add to strategy? Currently these are handled "specially":
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** PrimaryKeyJoinColumn
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*** joined-subclass key column(s) - JPA defaults
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*** secondary table key column(s) - JPA defaults
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*** one-to-one key column(s) - JPA defaults
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** entity simple identifier column - JPA defaults
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** entity version - currently uses #determineAttributeColumnName
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** collection-id column name - currently hard-coded as "id"
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** list-index column name - currently hard-coded as "idx"
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* hibernate.jdbc.batch_versioned_data default value is true, Oracle dialects set this property to false except for Oracle12cDialect
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= 5.0 Migration Guide
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:toc:
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This guide discusses migration from Hibernate ORM version 4.3 to version 5.0. For migration from
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earlier versions, see any other pertinent migration guides as well.
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== Re-purposing of Configuration
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Configuration, historically, allowed users to iteratively add settings and mappings in any order and to query the
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state of settings and mapping information in the middle of that process. Which meant that building the mapping
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information could not effectively rely on any settings being available. This lead to many limitations and problems.
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Quite a few methods have been removed from Configuration. Be sure to see the User Guide chapter on bootstrapping for
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details. For applications that integrate with Hibernate via one or more APIs, this change might effect your
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integrations as well.
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== Short-naming
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In an effort to insulate applications from refactoring efforts, Hibernate has begun to recognize "short name" values for
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certain configuration settings. These are discussed in detail in the User Guide in the pertinent sections.
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Where available, we highly recommend using the short name for a setting value.
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== Transactions
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The transaction SPI underwent a major redesign as part of 5.0 as well. From a user perspective this generally
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only comes into view in terms of configuration. Previously applications would work with the different backend
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transaction stratagies directly via the `org.hibernate.Transaction` API. In 5.0 a level of indirection has been
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added here. The API implementation of `org.hibernate.Transaction` is always the same now. On the backend, the
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`org.hibernate.Transaction` impl talks to a `org.hibernate.resource.transaction.TransactionCoordinator` which represents
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the "transactional context" for a given Session according to the backend transaction strategy. Users generally do not
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need to care about the distinction.
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The change is noted here because it might affect your bootstrap configuration. Whereas previously applications would
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specify `hibernate.transaction.factory_class` and refer to a `org.hibernate.engine.transaction.spi.TransactionFactory` FQN,
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with 5.0 the new contract is `org.hibernate.resource.transaction.TransactionCoordinatorBuilder` and is specified using the
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`hibernate.transaction.coordinator_class` setting. See `org.hibernate.cfg.AvailableSettings.TRANSACTION_COORDINATOR_STRATEGY`
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JavaDocs for additional details.
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The following short-names are recognized:
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`jdbc`::(the default) says to use JDBC-based transactions (`org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl`)
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`jta`::says to use JTA-based transactions (`org.hibernate.resource.transaction.backend.jta.internal.JtaTransactionCoordinatorImpl`)
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See the User Guide for additional details.
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== Type handling
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* Migrated `org.hibernate.metamodel.spi.TypeContributor` and `org.hibernate.metamodel.spi.TypeContributions`
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to `org.hibernate.boot.model.TypeContributor` and `org.hibernate.boot.model.TypeContributions`
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* Built-in `org.hibernate.type.descriptor.sql.SqlTypeDescriptor` implementations no longer auto-register themselves
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with `org.hibernate.type.descriptor.sql.SqlTypeDescriptorRegistry`. Applications using custom SqlTypeDescriptor
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implementations extending the built-in ones and relying on that behavior should be updated to call
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`SqlTypeDescriptorRegistry#addDescriptor` themselves.
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* The JDBC type for "big_integer" (org.hibernate.type.BigIntegerType) properties has changed from
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java.sql.Types,NUMERIC to java.sql.Types.BIGINT.
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* For ids defined as UUID with generation, for some databases it is required to explicitly set the `@Column( length=16 )`
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in order to generate BINARY(16) so that comparisons properly work.
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* For EnumType mappings defined in hbm.xml where the user wants name-mapping (`javax.persistence.EnumType#STRING`)
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the configuration must explicitly state that using either the `useNamed` (true) setting or by specifying the `type`
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setting set to the value 12 (VARCHAR JDBC type code).
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== Naming strategies
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Historically Hibernate provided just a singular contract for applying a "naming strategy". Starting in 5.0 this has
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been split into 2 distinct contracts:
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* `ImplicitNamingStrategy` - is used whenever a table or column is not explicitly named to determine the name to use.
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* `PhysicalNamingStrategy` - is used to convert a "logical name" (either implicit or explicit) name of a table or column
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into a physical name (e.g. following corporate naming guidelines)
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== Changed setting defaults
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* Default value for `hibernate.id.new_generator_mappings` setting changed to true for 5.0. See
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`org.hibernate.cfg.AvailableSettings#USE_NEW_ID_GENERATOR_MAPPINGS` javadocs.
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* The default ImplicitNamingStrategy (`hibernate.implicit_naming_strategy`) has changed to the JPA-compliant one. See
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`org.hibernate.cfg.AvailableSettings.IMPLICIT_NAMING_STRATEGY` javadocs for details. If you experience problems
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migrating dues to implicit table or column names you may want to specify the legacy strategy
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(`legacy-hbm` \ `org.hibernate.boot.model.naming.ImplicitNamingStrategyLegacyHbmImpl`).
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* `hibernate.jdbc.batch_versioned_data` default value is now true; Oracle dialects set this property to false,
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except for Oracle12cDialect
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== Misc
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* `cfg.xml` files are again fully parsed and integrated (events, security, etc)
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* properties loaded from `cfg.xml` through EntityManagerFactory did not previously prefix names with "hibernate." this is now made consistent.
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* `Configuration` is no longer `Serializable`
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* `org.hibernate.dialect.Dialect.getQuerySequencesString` expected to retrieve catalog, schema, and increment values as well
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* removed AuditConfiguration in preference for new `org.hibernate.envers.boot.internal.EnversService`
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* changed AuditStrategy method parameters from (removed) AuditConfiguration to (new) EnversService
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* Moving `org.hibernate.hql.spi.MultiTableBulkIdStrategy` and friends to new `org.hibernate.hql.spi.id` package
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and sub-packages
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* Complete redesign of "property access" contracts
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* Valid `hibernate.cache.default_cache_concurrency_strategy` setting values are now defined via
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`org.hibernate.cache.spi.access.AccessType#getExternalName` rather than the `org.hibernate.cache.spi.access.AccessType`
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enum names; this is more consistent with other Hibernate settings
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== Deprecations
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* Removed the deprecated `org.hibernate.cfg.AnnotationConfiguration`
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* Removed deprecated `org.hibernate.id.TableGenerator` id-generator
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* Removed deprecated `org.hibernate.id.TableHiLoGenerator` (hilo) id-generator
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* Deprecated `org.hibernate.id.SequenceGenerator` and its subclasses
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* Added a new dedicated "deprecation logger" to consolidate logging for deprecated uses.
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== Changed/Moved contracts
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* `org.hibernate.integrator.spi.Integrator` contract changed to account for bootstrap redesign
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* Extracted `org.hibernate.engine.jdbc.env.spi.JdbcEnvironment` from `JdbcServices`;
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created `org.hibernate.engine.jdbc.env` package and moved a few contracts there.
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* Introduction of `org.hibernate.boot.model.relational.ExportableProducer` which will effect any
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`org.hibernate.id.PersistentIdentifierGenerator` implementations
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* Changed to signature of `org.hibernate.id.Configurable` to accept `ServiceRegistry` rather than just `Dialect`
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@ -1,97 +0,0 @@
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Working list of changes for 5.0
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===================================
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* Switch from Configuration to ServiceRegistry+Metadata for SessionFactory building
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* `org.hibernate.hql.spi.MultiTableBulkIdStrategy#prepare` contract has been changed to account for Metadata
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* (proposed) `org.hibernate.persister.spi.PersisterFactory` contract, specifically building CollectionPersisters)
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has been changed to account for Metadata
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* extract `org.hibernate.engine.jdbc.env.spi.JdbcEnvironment` from `JdbcServices`; create
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`org.hibernate.engine.jdbc.env` package and moved a few contracts there.
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* Introduction of `org.hibernate.boot.model.relational.ExportableProducer` which will effect any
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`org.hibernate.id.PersistentIdentifierGenerator` implementations
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* Change to signature of `org.hibernate.id.Configurable` to accept `ServiceRegistry` rather than just `Dialect`
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* Removed deprecated `org.hibernate.id.TableGenerator` id-generator
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* Removed deprecated `org.hibernate.id.TableHiLoGenerator` (hilo) id-generator
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* Deprecated `org.hibernate.id.SequenceGenerator` and its subclasses
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* cfg.xml files are again fully parsed and integrated (events, security, etc)
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* Removed the deprecated `org.hibernate.cfg.AnnotationConfiguration`
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* `Integrator` contract
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* `Configuration` is no longer `Serializable`
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* `org.hibernate.dialect.Dialect.getQuerySequencesString` expected to retrieve catalog, schema, and increment values as well
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* properties loaded from cfg.xml through EMF did not previously prefix names with "hibernate." this is now made consistent.
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* removed AuditConfiguration in preference for new `org.hibernate.envers.boot.internal.EnversService`
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* changed AuditStrategy method parameters from (removed) AuditConfiguration to (new) EnversService
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* Built-in `org.hibernate.type.descriptor.sql.SqlTypeDescriptor` implementations no longer auto-register themselves
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with `org.hibernate.type.descriptor.sql.SqlTypeDescriptorRegistry`. Applications using custom SqlTypeDescriptor
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implementations extending the built-in ones and relying on that behavior should be updated to call
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`SqlTypeDescriptorRegistry#addDescriptor` themselves.
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* The JDBC type for "big_integer" (org.hibernate.type.BigIntegerType) properties has changed from
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java.sql.Types,NUMERIC to java.sql.Types.BIGINT.
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* Moving `org.hibernate.hql.spi.MultiTableBulkIdStrategy` and friends to new `org.hibernate.hql.spi.id` package
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and sub-packages
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* Changes to "property access" contracts, including
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* Valid `hibernate.cache.default_cache_concurrency_strategy` setting values are now defined via
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`org.hibernate.cache.spi.access.AccessType#getExternalName` rather than the `org.hibernate.cache.spi.access.AccessType`
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enum names; this is more consistent with other Hibernate settings
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* For ids defined as UUID with generation, for some databases it is required to explicitly set the `@Column( length=16 )`
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in order to generate BINARY(16) so that comparisons properly work.
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* For EnumType mappings defined in hbm.xml where the user wants name-mapping (`javax.persistence.EnumType#STRING`)
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the configuration must explicitly state that using either the `useNamed` (true) setting or by specifying the `type`
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setting set to the value 12 (VARCHAR JDBC type code).
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* Default value for `hibernate.id.new_generator_mappings` setting changed to true for 5.0. See
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`org.hibernate.cfg.AvailableSettings#USE_NEW_ID_GENERATOR_MAPPINGS` javadocs.
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* The default ImplicitNamingStrategy (`hibernate.implicit_naming_strategy`) has changed to the JPA-compliant one. See
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`org.hibernate.cfg.AvailableSettings.IMPLICIT_NAMING_STRATEGY` javadocs for details.
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TODOs
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=====
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* Still need to go back and make all "persistent id generators" to properly implement ExportableProducer
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* Add a setting to "consistently apply" naming strategies. E.g. use the "join column" methods from hbm.xml binding.
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* Along with this ^^ consistency setting, split the implicit naming strategy for join columns into multiple methods - one for each usage:
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* many-to-one
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* one-to-one
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* etc
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Blog items
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==========
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* New bootstrapping API - better determinism, better integration
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* Java 8 Support (though still compatible with Java 6).
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* hibernate-spatial
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* Ability to handle additional Java types for id attributes marked as `GenerationType#AUTO`. Built-in support
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for Number and UUID. Expandable via new `org.hibernate.boot.model.IdGeneratorStrategyInterpreter` extension
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* Expanded support for AttributeConverters.
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* fully supported for non-`@Enumerated` enum values
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* applicable in conjunction with `@Nationalized` support
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* called to handle null values
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* settable in hbm.xml by using `type="converter:fully.qualified.AttributeConverterName"`
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* integrated with hibernate-envers
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* collection values, map keys
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* scanning support for non-JPA usage
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* naming strategy split. default is now to be jpa-compliant
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* OSGi improvements, Karaf feature file published
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Proposals for discussion
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========================
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* Currently there is a "post-binding" hook to allow validation of the bound model (PersistentClass,
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Property, Value, etc). However, the top-level entry points are currently the only possible place
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(per contract) to throw exceptions when a validation fails". I'd like to instead consider a pattern
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where each level is asked to validate itself. Given the current model, however, this is unfortunately
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not a win-win situation. `org.hibernate.boot.model.source.internal.hbm.ModelBinder#createManyToOneAttribute`
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illustrates one such use case where this would be worthwhile, and also can illustrate how pushing the
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validation (and exception throwing down) can be less than stellar given the current model. In the process
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of binding a many-to-one, we need to validate that any many-to-one that defines "delete-orphan" cascading
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is a "logical one-to-one". There are 2 ways a many-to-one can be marked as a "logical one-to-one"; first
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is at the `<many-to-one/>` level; the other is through a singular `<column/>` that is marked as unique.
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Occasionally the binding of the column(s) of a many-to-one need to be delayed until a second pass, which
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means that sometimes we cannot perform this check immediately from the `#createManyToOneAttribute` method.
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What would be ideal would be to check this after all binding is complete. In current code, this could be
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either an additional SecondPass or done in a `ManyToOne#isValid` override of `SimpleValue#isValid`. The
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`ManyToOne#isValid` approach illustrates the conundrum... In the `ManyToOne#isValid` call we know the real
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reason the validation failed (non-unique many-to-one marked for orphan delete) but not the property name/path.
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Simply returning false from `ManyToOne#isValid` would instead lead to a misleading exception message, which
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would at least have the proper context to know the property name/path.
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* Consider an additional "naming strategy contract" specifically for logical naming. This would be non-pluggable, and
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would be the thing that generates the names we use to cross-reference and locate tables, columns, etc.
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