Transactions are a fundamental part of any database-backed application. In a nutshell, a transaction is a way to bundle one or more database operations into an atomic unit. Either all of the operations succeed, or none of them do.
There are many benefits to using transactions, including:
In this article, we'll take a look at how to use transactions with Spring Boot and Hibernate. We'll start with a quick overview of the different types of transactions, and then we'll dive into some code examples.
There are two main types of transactions: local and global.
A local transaction is one that is managed by a single resource, such as a database. In a local transaction, all of the operations must be done on the same database. If any of the operations fail, the entire transaction is rolled back and the database is left in its original state.
A global transaction is one that is managed by multiple resources, such as a database and a message queue. Global transactions are more complex than local transactions, but they offer the benefit of being able to roll back the entire transaction even if one of the resources fails.
Spring Boot provides first-class support for transactions. In fact, transactions are so important that Spring Boot application will not start if it detects that the database is not configured for transactions.
When configuring transactions in Spring Boot, there are three things to keep in mind:
The most common way to configure transactions in Spring Boot is to use the @Transactional annotation. This annotation can be added to a class or a method. When added to a class, it applies to all of the methods in the class. When added to a method, it only applies to that method.
The @Transactional annotation has a few optional parameters that can be used to customize its behavior. The most important of these is the isolation level. The isolation level is used to control how strictly the database enforces the ACID properties.
There are four isolation levels that are commonly used:
It's important to choose the right isolation level for your application. If you choose an isolation level that is too strict, you may see performance problems. If you choose an isolation level that is too lax, you may see data inconsistencies.
Hibernate is a popular ORM tool that is often used in conjunction with Spring. Hibernate also supports transactions, and it offers a few different ways to configure them.
The most common way to configure transactions in Hibernate is to use the @Transactional annotation. This annotation can be added to a class or a method. When added to a class, it applies to all of the methods in the class. When added to a method, it only applies to that method.
The @Transactional annotation has a few optional parameters that can be used to customize its behavior. The most important of these is the isolation level. The isolation level is used to control how strictly the database enforces the ACID properties.
Hibernate also supports programmatic transactions. This means that you can configure the transaction in code, rather than using an annotation. This is generally not recommended, as it makes the code more difficult to understand and maintain.
In this article, we've looked at how to use transactions with Spring Boot and Hibernate. We've seen how to configure transactions using the @Transactional annotation, and we've also seen how to choose the right isolation level for our needs.