Blog - Vlad Mihalcea

Posted on February 25, 2020 by vladmihalcea

Hibernate slow query log

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Introduction

In this article, I’m going to show you how you can activate the slow query log when using JPA and Hibernate.

This slow query log feature has been available since Hibernate ORM 5.4.5 and notifies you when the execution time of a given JPQL, Criteria API or native SQL query exceeds a certain threshold value you have previously configured.

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Posted on February 18, 2020 by vladmihalcea

Hypersistence Optimizer Runtime Scanner

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Introduction

The 2.0 version of the Hypersistence Optimizer has just arrived, and it comes with a runtime scanner that is capable of analyzing your JPA and Hibernate data access operations and queries and give you tips about how you can speed up your application.

Along with the JPA and Hibernate mapping and configuration scanners, the runtime scanner makes Hypersistence Optimizer an indispensable tool for building High-Performance Java Persistence applications.

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Posted on February 14, 2020 by vladmihalcea

Java and Database Newsletter, Issue 3

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Introduction

Welcome to a new issue of the Java and Database newsletter in which we share articles, announcements, and StackOverflow answers that are very relevant to any developer who interacts with a database system from Java.

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Posted on February 11, 2020 by vladmihalcea

PostgreSQL triggers and isolation levels

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Introduction

In this article, we are going to see how the PostgreSQL isolation levels guarantee read and write consistency when executing database triggers.

While relational database systems provide strong data integrity guarantees, it’s very important to understand how the underlying transactional engine works in order to choose the right design for your data access layer.
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Posted on February 5, 2020 by vladmihalcea

How to map a PostgreSQL ARRAY to a Java List with JPA and Hibernate

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Introduction

In this article, I’m going to show you how to map PostgreSQL ARRAY column types (e.g., text, int, double, enum, date, timestamp, UUID) to Java List entity attributes with JPA and Hibernate.

While the Hibernate Types project has been supporting PostgreSQL ARRAY column types since the very first version, prior to version 2.9, you could only map database ARRAY columns to Java Array entity attributes, as illustrated by this article.

Mapping database ARRAY columns to java.util.List entity attributes is a much better approach than using the previous Java Array option since, most often, it’s more convenient to use Java Collections than Arrays.

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Posted on January 31, 2020 by vladmihalcea

Java and Database Newsletter, Issue 2

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Introduction

Welcome to a new issue of the Java and Database newsletter in which we share articles, announcements, and StackOverflow answers that are very relevant to any developer who interacts with a database system from Java.

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Posted on January 28, 2020 by vladmihalcea

SQL EXISTS and NOT EXISTS

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Introduction

In this article, we are going to see how the SQL EXISTS operator works and when you should use it.

Although the EXISTS operator has been available since SQL:86, the very first edition of the SQL Standard, I found that there are still many application developers who don’t realize how powerful SQL subquery expressions really are when it comes to filtering a given table based on a condition evaluated on a different table.

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Posted on January 21, 2020 by vladmihalcea

How to return a Map result from a JPA or Hibernate query

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Introduction

In this article, I’m going to show you how you can return a Java Map result when executing a JPA query. I decided to write this article after answering a similar question on StackOverflow.

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Posted on January 17, 2020 by vladmihalcea

Java and Database Newsletter, Issue 1

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Introduction

I started my newsletter in November 2015, and every time I was publishing a new article, I would send it to my newsletter subscribers as well.

This year, I decided to change the format of my newsletter. Instead of creating a new issue for every article, the newsletter will now contain links to the best articles I read over the past two weeks.

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Posted on January 14, 2020 by vladmihalcea

Multidimensional array mapping with JPA and Hibernate

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Introduction

In this article, I’m going to present the best way to map a Java multidimensional array when using JPA and Hibernate.

While one-dimensional array types have long been supported by the Hibernate Types open-source project, starting with the 2.9 release, you can now persist multidimensional array entity attributes with JPA and Hibernate.

Vlad Mihalcea

Hibernate slow query log

Introduction

Hypersistence Optimizer Runtime Scanner

Introduction

PostgreSQL triggers and isolation levels

Introduction

SQL EXISTS and NOT EXISTS

Introduction

How to return a Map result from a JPA or Hibernate query

Introduction

Multidimensional array mapping with JPA and Hibernate

Introduction

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