Building Fast and Scalable Persistence Layers with Spring Data JPA
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The document discusses creating fast and scalable persistence layers using Spring Data JPA, emphasizing best practices for performance and problem identification. It covers various fetching strategies for associations, caching mechanisms, and provides code samples to illustrate effective use of Hibernate and JPA features. The author also promotes an online course for structured learning in Spring Data JPA.
Building Fast and Scalable Persistence Layers with Spring Data JPA
- 1. Building Fast and Scalable Persistence Layers with Spring Data JPA
- 2. Thorben Janssen Independent consultant, trainer and author @thjanssen123 /c/ThoughtsOnJava thorbenjanssenofficial Hibernate Tips More than 70 solutions to common Hibernate problems www.hibernate-tips.com Co-Organizer JUG Paderborn thorben-janssen.com
- 4. Find problems as early as possible Avoid / Fix performance problems Performance
- 5. Persistence provider: Hibernate o Follow best practices o Avoid pitfalls Performance
- 7. Activate via system property o hibernate.generate_statistics = true Configure logging o org.hibernate.stat = DEBUG Hibernate Statistics
- 8. Configure threshold o hibernate.session.events.log.LOG_QUERIES_SLO WER_THAN_MS Slow Query Log
- 9. Code Samples
- 11. Defines when the relationship will be fetched Static definition in entity mapping FetchType @ManyToOne(fetch = FetchType.LAZY) private Publisher publisher;
- 12. FetchType Lazy o Relationship gets loaded at first access o Default for to-many relationships Eager o Loads relationships immediately o Default for to-one relationships
- 13. To-many relationships o Stick to the default mapping (FetchType.LAZY) o Use eager fetching for specific queries, if required To-one relationships o Check existing mappings individually o Use FetchType.LAZY for new ones Recommendation
- 15. Most common problems o Lazy fetching of related entities N+1 Select? List<Author> authors = this.em.createQuery("SELECT a FROM Author a", Author.class).getResultList(); for (Author a : authors) { System.out.println("Author " + a.getFirstName() + " " + a.getLastName() + " wrote " + a.getBooks().size() + “ Books.”)); }
- 16. Fetch all required entities with one query o Fetch Joins o EntityGraph Query-Specific fetching
- 17. Code Samples
- 19. Inefficient handling of List o Remove all associations o Add remaining ones Use Set instead Many-to-Many
- 20. Code Samples
- 21. Projections
- 22. Entities Scalar values DTO Projections
- 23. DTO classes DTO interfaces o Spring Data JPA generates class DTO Projections
- 24. Code Samples
- 25. Nested associations Spring Expression Language Advanced DTO Projections
- 26. Code Samples
- 27. Caching
- 29. 2nd Level Cache
- 30. Session independent entity store Needs to be activated o application.properties Transparent usage PersistenceProvider doesn‘t need to provide it 2nd Level Cache
- 31. ALL all entities NONE no entities ENABLE_SELECTIVE requires activation DISABLE_SELECTIVE can be deactivated UNSPECIFIED use default settings Shared Cache Mode
- 32. Code Samples
- 33. Spring Data JPA – Online Course Learn Spring Data JPA in a structure way to build efficient and maintainable persistence layers https://thorben-janssen.com/course-spring-data-jpa/