Bulk Update and Delete with JPA and Hibernate

Introduction JPA and Hibernate allow us to execute bulk update and delete queries so that we can process multiple rows that match the business use case filtering criteria. When modifying multiple records, you have two options. You could either use batch processing or bulk processing. While batch processing is useful when entities are already managed by the current Persistence Context because it can reduce the number of INSERT, UPDATE, or DELETE statements that get executed, bulk processing allows us to modify the underlying database records with a single SQL statement.

How to get the SQL query from JPQL or JPA Criteria

Introduction In this article, I’m going to show you how you can get the auto-generated SQL query from a JPQL or JPA Criteria API entity query.

Multiline String literals with Java Text Blocks

Introduction In this article, show you how the new Java Text Blocks can help you increase the readability of JPQL, SQL queries, or JSON string values. Back in 2005, I was developing a .NET project and really liked the C# Verbatim String Literal feature since it allows you to write a multiline string value without having to concatenate each individual line. The Java 13 Text Blocks feature now offers the possibility of creating a multiline Java String values.

Bulk update optimistic locking with JPA and Hibernate

Introduction In this article, we are going to see how we can adjust a bulk update statement so that it takes optimistic locking into consideration. While Hibernate has been supporting versioned HQL queries for a very long time, it’s actually very easy to achieve this goal even with standard JPQL or JPA Criteria API.

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.

The best way to use SQL functions in JPQL or Criteria API queries with JPA and Hibernate

Introduction When executing an entity query (e.g. JPQL, HQL or Criteria API), you can use any SQL function without having to register it as long as the function is passed directly to the WHERE clause of the underlying SQL statement. However, if the SQL function is used in the SELECT clause, and Hibernate has not registered the SQL function (be it a database-specific or user-defined function), you will have to register the function prior to using it in an entity query. In this article, you are going to learn various ways to… Read More

A beginner’s guide to the Hibernate JPQL and Native Query Plan Cache

Introduction Every JPQL query must be compiled prior to being executed, and, because this process might be resource-intensive, Hibernate provides a QueryPlanCache for this purpose. For entity queries, the query String representation is parsed into an AST (Abstract Syntax Tree). For native queries, the parsing phase cannot compile the query, so it only extracts information about the named parameters and query return type.

How to map an immutable entity with JPA and Hibernate

Introduction In this article, you are going to find out how to map an immutable entity when using JPA and Hibernate. If your Domain Model requires that a given entity should not be modified by the data access logic, Hibernate can enforce this requirement if the entity is marked with the @Immutable annotation.

How to JOIN unrelated entities with JPA and Hibernate

Introduction Answering questions on the Hibernate forum is a neverending source of inspiration. The following question is about joining unrelated entities using entity queries, and this post is going to explain how you can do it when using JPA and Hibernate.

EAGER fetching is a code smell when using JPA and Hibernate

Introduction Hibernate fetching strategies can really make a difference between an application that barely crawls and a highly responsive one. In this post, I’ll explain why you should prefer query-based fetching instead of global fetch plans. Fetching 101 Hibernate defines four association retrieving strategies: Fetching Strategy Description Join The association is OUTER JOINED in the original SELECT statement Select An additional SELECT statement is used to retrieve the associated entity(entities) Subselect An additional SELECT statement is used to retrieve the whole associated collection. This mode is meant for to-many associations Batch An… Read More