How to execute SQL functions with multiple parameters in a JPQL query with Hibernate

Introduction In this article, we are going to see how you can execute SQL functions with multiple parameters in JPQL queries with Hibernate. I recently stumbled on this requirement while answering this StackOverflow question which is a never-ending source of inspiration for articles on my blog.

The best way to use the JPQL DISTINCT keyword with JPA and Hibernate

Introduction In this article, we are going to how the JPQL DISTINCT keyword behaves depending on the underlying entity query type.

How to map camelCase properties to snake_case column names with Hibernate

Introduction In this article, you are going to learn how to map cameCase entity properties (e.g. phoneNumber) to snake_case column names (e.g. phone_number) using a Hibernate naming strategy. While you could achieve the same goal with the name attribute of JPA @Column annotation, it’s much more convenient to use a custom Hibernate strategy to apply this naming convention consistently.

How to optimize JPQL and Criteria API query plans with Hibernate Statistics

Introduction Every entity query, be it JPQL or Criteria API, needs to be parsed and compiled to an AST (Abstract Syntax Tree) in order to generate the associated SQL query. The entity query compilation takes time, as explained in this article so Hibernate provides a QueryPlanCache to store already-compiled plans. Starting with Hibernate 5.4, the Hibernate Statistics mechanism allows you to monitor the Query Plan Cache and this article will show you how to take advantage of this feature to speed up IN query performance. For an introduction about the Hibernate Statistics… Read More

How to merge entity collections with JPA and Hibernate

Introduction In this article, you are going to learn why overwriting entity collections is an anti-pattern and how you can merge collections both effectively and efficiently with JPA and Hibernate. The reason I decided to write this article is that I’ve been this question asked over and over and over again.

How to map java.time.Year and java.time.Month with JPA and Hibernate

Introduction In this article, we are going to see how you can map the java.time.Year and java.time.Month with both JPA and Hibernate. As explained in this article, JPA 2.2 supports LocalDate, LocalTime, LocalDateTime, OffsetTime, OffsetDateTime from the java.time package. Hibernate has been supporting the Java 8 Date/Time classes since 5.0 via the hibernate-java8 dependency, but since version 5.2, this dependency was merged with hibernate-core so you get the Duration, Instant and ZonedDateTime types in addition to the ones supported by JPA 2.2. However, neither JPA nor Hibernate supports the java.time.Year type out-of-the-box…. Read More

How to map the Java YearMonth type with JPA and Hibernate

Introduction In this article, we are going to see how you can map a java.time.YearMonth with both JPA and Hibernate. As I explained in this article, JPA 2.2 supports the following Date/Time types introduced in Java 8: java.time.LocalDate java.time.LocalTime java.time.LocalDateTime java.time.OffsetTime java.time.OffsetDateTime Apart from supporting those, Hibernate supports also: java.time.Duration java.time.Instant java.time.ZonedDateTime However, neither JPA nor Hibernate support the java.time.YearMonth out-of-the-box. As you will see, adding support for java.time.YearMonth is really straightforward for both standard JPA or Hibernate.

Query pagination with JPA and Hibernate

Introduction Inspired by this StackOverflow answer I gave recently, I decided it’s time to write an article about query pagination when using JPA and Hibernate. In this article, you are going to see how to use query pagination to restrict the JDBC ResultSet size and avoid fetching more data than necessary.

Spring read-only transaction Hibernate optimization

Introduction In this article, I’m going to explain how the Spring read-only transaction Hibernate optimization works. After taking a look at what the Spring framework does when enabling the readOnly attribute on the @Transactional annotation, I realized that only the Hibernate flush mode is set to FlushType.MANUAL without propagating the read-only flag further to the Hibernate Session. So, in the true spirit of open-source software developer, I decided it’s time to make a change.

Hibernate performance tuning tips

Introduction In this article, I’m going to summarise the most common Hibernate performance tuning tips that can help you speed up your data access layer. While getting started with JPA and Hibernate is fairly easy, if you want to get the most out of your data access layer, it’s very important to understand how the JPA provider works, as well as the configuration properties that can help you optimize application performance.