Not Just ORM: Powerful Hibernate ORM Features and Capabilities
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The document presents advanced features and capabilities of Hibernate ORM, elucidating its support for object-relational mapping, multi-tenancy strategies, value generation, and integrations with various technologies like spatial data and auditing. It highlights improvements in.hibernate ORM 4.3 and 5, such as custom annotations, built-in generators, and support for NoSQL with Hibernate OGM. Various modules like Hibernate Search for full-text queries and Hibernate Envers for versioning enhance data interaction and management in applications.
![Hibernate Envers
• Provides historical versioning and auditing (“SCM for data”)
• Each transaction == a “revision”
• Revision #s are global --> querying for a historical snapshot
of the entire database is possible
• Requires
– @Audited on the entity or individual properties
– [entity]_AUD tables to store the historical data (DDL created
automated if using hbm2ddl, otherwise it’s exportable)
• Duplicate data? Yes.
• Powerful queries/capabilities > cheap mem
• Highly configurable](https://image.slidesharecdn.com/hibernateormfeatures-140223193044-phpapp02/85/Not-Just-ORM-Powerful-Hibernate-ORM-Features-and-Capabilities-21-320.jpg)
Not Just ORM: Powerful Hibernate ORM Features and Capabilities
- 2. Not Just ORM: Powerful Hibernate ORM Features and Capabilities Brett Meyer Senior Software Engineer Hibernate ORM, Red Hat
- 3. Brett Meyer • Hibernate ORM – ORM 4 & 5 development – Hibernate OSGi – Developer community engagement – Red Hat support, Hibernate engineering lead • Other contributions – Apache Camel – Infinispan • Contact me – @brettemeyer or +brettmeyer – Freenode #hibernate or #hibernate-dev (brmeyer)
- 5. ORM? JPA? • ORM: Object/Relational Mapping – Persistence: Data objects outlive the JVM app – Maps Java POJOs to relational databases – Supports OO concepts: inheritance, object identity, etc. – Navigate data by walking the object graph, not the explicit relational model • JPA: Java Persistence API • Hibernate ORM provides its own native API, in addition to full JPA support • Annotations and XML
- 6. Overview • • • • • • • • • Multi-Tenancy Value Generation Hibernate Spatial Hibernate Envers Hibernate OSGi Hibernate Search Hibernate OGM & Validator Hibernate Shards Ask questions after each section!
- 8. Multi-Tenancy • • • • 1 ORM instance Multiple concurrent clients Data specific to each tenant Legacy – Separate SessionFactories for each tenant – Application-provided Connections (given when opening a Session) – Big schemas or many tenants = huge footprint
- 9. Hibernate ORM Multi-Tenancy • • • • Strategy selection is global Tenant identifier provided when opening a Session Works with 2LC: identifier used in cache data key Custom impls: – MultiTenantConnectionProvider: required for physical and schema separated (required) – CurrentTenantIdentifierResolver: required for opening a Session without providing the tenant id (explicitly or Session#getCurrentSession)
- 10. Hibernate ORM Multi-Tenancy Strategies • Physically separated databases – 1 JDBC connection pool per tenant – Pool selected based on tenant identifier • Single database, separate schemas – Option #1 • Similar to physically separated • 1 JDBC connection pool per tenant • Provides schema through the connection URL or pool – Option #2: • 1 JDBC connection pool using a default schema • Each Connection altered with SQL “SET SCHEMA” prior to use
- 11. Hibernate ORM Multi-Tenancy Strategies • Single database and schema – Data partitioned by discriminator value – Discriminator complexity varies – Each SQL statement altered to include the discriminator – Not yet implemented (planned for ORM 5) – Alternative: @FilterDef/@Filter w/ a tenantId as a param
- 12. Hibernate ORM Multi-Tenancy • DEMO • Questions?
- 13. Value Generation
- 14. Value Generation (Legacy) • Limited to in-database value generation on insert/update • Properties marked with @Generated immediately selected
- 15. Hibernate ORM Value Generation • • • • New, expanded support in ORM 4.3 Supports legacy in-DB generation, but also in-mem Create custom annotations! ORM provides built in generators – @Generated: legacy, providing in-database generation – @CreationTimestamp: set only once when owning entity is saved for the first time – @UpdateTimestamp: set any time owning entity is saved – @GeneratorType: provide custom in-memory generator and define “when” • DEMO • Questions?
- 17. Hibernate Spatial • Currently 3rd party, but pulling in as a new ORM module in 5 • Originally created by Karel Maesen (geovise.com) • Java Topology Suite (JTS) – OpenGIS Simple Feature Spec (SFS) & SQL/MM Spatial (extends SFS) – Oracle, Postgres, MySQL, MS SQL, H2, etc. all implement the specs – Attempts to provide abstract, cross-platform geo data, but diffs between them • geolatte-geom – Developed/maintained by Karel – Improvement over JTS – Fully interoperable with JTS – Support for lat/lon geographies – Additional Dialect differences
- 18. Hibernate Spatial (cont'd) • Properties use JTS Geometry types – Point – LineString – Polygon – etc. • Adds HQL functions for Dialect-supported methods – Same functions also implemented as Criteria API Criterions – ex: "select e from Event e where within(e.location, :filter) = true" (:filter is a Geometry) – http://www.hibernatespatial.org/documentation/03-dialects/0 1-overview/
- 19. Hibernate Spatial (cont'd) • Translates between “Well-known text” (WKT) and Geometry types – Spatial object markup language – 2D and 3D – ex: “POINT (30 10)”, “POLYGON ((30 10, 40 40, 20 40, 10 20, 30 10))” • Coordinate system transformations possible in queries • Does not require JDBC extension drivers (ex: Oracle SDOAPI.jar or Postgres postgis.jar) • DEMO • Questions?
- 20. Hibernate Envers
- 21. Hibernate Envers • Provides historical versioning and auditing (“SCM for data”) • Each transaction == a “revision” • Revision #s are global --> querying for a historical snapshot of the entire database is possible • Requires – @Audited on the entity or individual properties – [entity]_AUD tables to store the historical data (DDL created automated if using hbm2ddl, otherwise it’s exportable) • Duplicate data? Yes. • Powerful queries/capabilities > cheap mem • Highly configurable
- 22. Hibernate Envers (cont'd) • Revision info – Default: simple internal entity stored in REVINFO table – Revision # and revision timestamp – Override with custom @RevisionEntity & RevisionListener (add other useful fields: IP address, “blame”, etc.) • Revision entity types – Track the entity types that were changed in each revision – Disabled by default: requires querying tables for changed data – Can be overridden by implementing EntityTrackingRevisionListener on your RevisionEntity
- 23. Hibernate Envers (cont'd) • Revision properties – Track the entity properties that were changed in each revision – Disabled by default: requires querying tables for changed data – Adds boolean columns to audit tables • Queries – Snapshot of entity states at a given revision (horizontal) – Revisions at which entities changed (vertical) • DEMO • Questions? • Conditional auditing – Default: Envers auditing reacts to Hibernate ORM events – Disable hibernate.listeners.envers.autoRegister, create your own listeners, wire them in using Integrator
- 24. Hibernate OSGi
- 25. Hibernate OSGi • OSGi? • Provide only the OSGi manifest and hacky workarounds <-NO! • Emphasize doing things “the OSGi way” – Dynamic environment – Scoping • Limited visibility into the container • No scanning all bundles • Reduced conflicts, allows concurrent instances, etc. – OSGi services • Isolated in hibernate-osgi module (no pervasive dependencies or OSGi code)
- 26. Hibernate OSGi (cont'd) • 3 supported environments – Enterprise OSGi Managed JPA • Container discovers and manages persistence units and EntityManagerFactories • Similar to many app servers, Spring, etc. • Ex: Apache Aries JPA – Un-managed JPA • Direct use of hibernate-entitymanager • EntityManagerFactories created through OSGi services – Native • Direct use of hibernate-core • SessionFactories created through OSGi services • Quickstarts • Questions?
- 27. Hibernate Search
- 28. Hibernate Search • Full-text search on the DB – Bad performance – CPU/IO overhead • Offload full-text queries to Hibernate Search engine – Fully indexed – Horizontally scalable • Based on Apache Lucene • “Google for your entities”
- 29. Hibernate Search (cont'd) • Annotate entities with @Indexed • Annotate properties with @Field – Index the text: index=Index.YES – “Analyze” the text: analyze=Analyze.YES • • • • • Lucene analyzer Chunks sentences into words Lowercase all of them Exclude common words (“a”, “the”) Stemming
- 30. Hibernate OGM & Hibernate Validator
- 31. Hibernate OGM & Validator • Hibernate OGM: – ORM/JPA support for NoSQL – Infinispan, EHCache, MongoDB, Neo4j • Hibernate Validator – Bean Validation impl, but extended – Both annotation and XML based – @NotNull, @Size(min = 2, max = 14), @Min(2), etc.
- 32. Hibernate Shards
- 33. Hibernate Shards • Started as a Google team's 20% project • Horizontal partitioning across multiple databases • Flexible sharding strategies, both provided and custom • Supports virtual shards: simplifies re-sharding • Typical Hibernate ORM usage: HQL, Criteria, etc. • Last supported ORM version: 3.6.x • Currently has upgrade momentum – contact me if interested!
- 35. Hibernate ORM: Tips, Tricks, and Performance Techniques Tomorrow, 1pm, Ballroom D
- 36. QUESTIONS? • • • • Q&A #hibernate or #hibernate-dev (brmeyer) @brettemeyer +brettmeyer