How to enable multi-row inserts with the PostgreSQL reWriteBatchedInserts configuration property

Introduction

Vladimir Sitnikov has been working on many optimizations to the PostgreSQL JDBC Driver, and one of these is the reWriteBatchedInserts configuration property which he recently told me about.

In this article, you will see how the reWriteBatchedInserts JDBC configuration property works in PostgreSQL, and how it allows you to rewrite INSERT statements into a multi-VALUE INSERT.

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How to map Java and SQL arrays with JPA and Hibernate

Introduction

Hibernate custom Types allow you to map all sorts of database specific column types, like IP address, JSON columns, bit sets or SQL arrays.

There are two ways to define a custom Hibernate Type:

The latter option is preferred since it allows you to better split the Java-to-JDBC and the JDBC-to-SQL type handling. In this article, we are going to see how you can map SQL arrays to their Java counterpart.

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The best way to soft delete with Hibernate

Introduction

Each database application is unique. While most of the time, deleting a record is the best approach, there are times when the application requirements demand that database records should never be physically deleted.

So who uses this technique?

For instance, StackOverflow does it for all Posts (e.g. Questions and Answers). The StackOverflow Posts table has a ClosedDate column which acts as a soft delete mechanism since it hides an Answer for all users who have less than 10k reputation.

If you’re using Oracle, you can take advantage of its Flashback capabilities, so you don’t need to change your application code to offer such a functionality. Another option is to use the SQL Server Temporal Table feature.

However, not all relational database systems support Flashback queries, or they allow you to recover a certain record without having to restore from a database backup. In this case, Hibernate allows you to simplify the implementation of soft deletes, and this article is going to explain the best way to implement the logical deletion mechanism.

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How does a relational database work

Introduction

While doing my High-Performance Java Persistence training, I came to realize that it’s worth explaining how a relational database works, as otherwise, it is very difficult to grasp many transaction-related concepts like atomicity, durability, and checkpoints.

In this post, I’m going to give a high-level explanation of how a relational database works internally while also hinting some database-specific implementation details.

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