This presentation is about best practices when using hibernate and Spring Data JPA. I'm sharing commons problems and possible solutions to them, and also the demo project is in Github, I hope you like.

1. Tips about
Hibernate with
Spring Data JPA
Thiago dos Santos Hora

2. Purpose of this presentation

3. Purpose of this presentation
● Alignment of knowledge

4. Purpose of this presentation
● Alignment of knowledge
● Discuss best practices

5. Purpose of this presentation
● Alignment of knowledge
● Discuss best practices
● Demonstrate problems and possible solutions

6. Purpose of this presentation
● Alignment of knowledge
● Discuss best practices
● Demonstrate problems and possible solutions
● Review the way we use JPA

7. A little bit of context
● JPA: Java Persistence API, Java specification responsible for defining a standard way to
work with ORM between different providers.
● Hibernate: Started in 2001, the most popular ORM Java Framework.
● Spring Data JPA: One of the best spring projects, abstracts all the data access layer
using interface and removing almost all boilerplate.
In other words, these tools help us to focus on business logic instead of writing the same
repetitive code over and over again, thus making the developers more business oriented.

8. Cool!!!! but...

9. Be careful
● As always, everything comes at a price.
● When we are dealing with a critical system where performance is paramount, we need
to pay closer attention to the way we access our data, in order to use strictly the bare-
minimum.
● These frameworks can help us, but, without the correct use of the tools that they
provide us with, we can end up having big performance problems.
So, let's look at some of these potential problems.

10. Our scenario

11. Our scenario

12. Our scenario

13. Our scenario

14. Starting with something simple:
Now, let's take a look at the generated query, just to make sure everything is fine...

15. Surprise!!!

16. N+1 Query Problem
● Relationship
● Performance
● Fetching plan
● Select statement

17. How to solve these problems?

18. FetchTypes
● Lazy
● Eager

19. Output

20. But sometimes you do need the data.
● Lazy loading data

21. Example

22. Problem
Output:

23. But sometimes you do need the data.
● Lazy loading data
● LazyInitializationException

24. Solution

25. Solution

26. But sometimes you do need the data.
● Lazy loading data
● LazyInitializationException
● Transactions

27. Solution

28. Moving forward, it's time to OneToOne
mapping
● Mapping Lazy One to One Relationship

29. Adding author contact information

30. Example

31. What?

32. Moving forward, it's time to OneToOne
mapping
● Mapping Lazy One to One Relationship
● Hibernate Issues

33. Hibernate one to one issue

34. Moving forward, it's time to OneToOne
mapping
● Mapping Lazy One to One Relationship
● Hibernate Issues
● Approches

35. Example

36. Not yet…

37. Moving forward, it's time to OneToOne
mapping
● Mapping Lazy One to One Relationship
● Hibernate Issues
● Approches
● Different alternatives to solve this

38. First, bytecode enhancement.

39. First, bytecode enhancement.

40. First, bytecode enhancement.

41. First, bytecode enhancement.

42. First, bytecode enhancement.
Running options

43. First, bytecode enhancement.
Running options

44. First, bytecode enhancement.

45. First, bytecode enhancement.

46. Second, hibernate bypass

47. Second, hibernate bypass

48. Second, hibernate bypass

49. Second, hibernate bypass

50. Third, avoid the bidirectional mapping

51. Third, avoid the bidirectional mapping

52. OK, but what if I need the all data?
● JPQL
● Join Fetch

53. Solution

54. Solution

55. In case you do not have defined the
FetchType as Lazy

56. OK, but what if I need the all data?
● JPQL
● Join Fetch
● Entity Graph

57. Example

58. Example

59. In case you do not have defined the
FetchType as Lazy

60. If you want to contribute with Hibernate

61. If you want to contribute with Hibernate

62. OK, but what if I need the all data?
● JPQL
● Join Fetch
● Entity Graph
● Named Entity Graph

63. Example

64. Output

65. In case you do not have defined the
FetchType as Lazy

66. That is not all about EntityGraphs.

67. That is not all about EntityGraphs.

68. That is not all about EntityGraphs.

69. Solution

70. Solution

71. What if you cannot update the Hibernate
version?
● Specifications
● Base Repository
● Extend spring repository functionalities

72. Solution

73. Solution
* must have the same name as the interface plus the suffix "Impl".

74. Solution

75. Solution

76. Solution

77. Let us talk about large amounts of data
● PagingAndSortingRepository
● Page Size
● Memory

78. Example

79. Example

80. Output

81. About the Batching of operations
● Batching
● Size
● Define properties
● Make sure your Hibernate provides batching support for your DB

82. Example

83. Example

84. Example

85. Example

86. Output

87. Project on Github
● https://github.com/thiagohora/tipsabouthibernatespringdatajpa (Demo project)

88. References
● https://docs.spring.io/spring-data/jpa/docs/current/reference/html/ (Spring data jpa
documentation)
● https://hibernate.org/orm/documentation/5.4/ (Hibernate documentation)
● https://hibernate.atlassian.net/browse/HHH-9515 (One-to-one issue)
● https://vladmihalcea.com/the-best-way-to-map-a-onetoone-relationship-with-jpa-and-
hibernate/(Best way to map one-to-one)
● http://justonjava.blogspot.com/2010/09/lazy-one-to-one-and-one-to-many.html (one-to-one
inverse relationship)
● https://hibernate.atlassian.net/browse/HHH-8776 (Entity graphs handle no lazy attributes)
● https://www.baeldung.com/jpa-entity-graph (What the entity graph tries to resolve)
● https://blog.ippon.tech/boost-the-performance-of-your-spring-data-jpa-application/ (Boost the
performance of your Spring data jpa app)
● https://hibernate.atlassian.net/browse/HHH-10297 (Entity graph in clause issue)
● https://www.solidsyntax.be/2013/10/17/fetching-collections-hibernate/ (FetchMode)

89. References
● https://vladmihalcea.com/how-to-batch-insert-and-update-statements-with-hibernate/
● https://vladmihalcea.com/the-best-way-to-map-a-onetoone-relationship-with-jpa-and-hibernate/
● https://www.baeldung.com/spring-data-jpa-batch-inserts
● https://vladmihalcea.com/how-to-customize-the-jdbc-batch-size-for-each-persistence-context-
with-hibernate/ (Batching operations)