When working with JPA (Java Persistence API) and defining entity classes, it’s crucial to avoid using reserved words as identifiers for attributes or table names. Failure to do so may lead to SQL syntax errors, as demonstrated by the given issue.
In this tutorial, we’ll walk through the steps to resolve the SQL syntax error caused by using reserved words in a JPA entity class.
In JPA (Java Persistence API) and Hibernate applications, queries can sometimes take a long time to execute, especially when working with large data sets. To avoid long-running queries, it’s important to set a query timeout, which limits the maximum amount of time that a query is allowed to run before it times out. In this tutorial, we will learn how to set a query timeout for JPA/Hibernate applications.
A fairly common question for developers approaching Object Relational Mapping (ORM) tools like Hibernate is what is the difference between Hibernate and JPA. In this article we are going to explain it in a nutshell. From an high level view, JPA is just like an interface without a concrete implementation of it. On the other … Read more
In this short tutorial we will show how to use variables in your persistence.xml so that you can dynamically specify the data source which is used by our application. In WildFly the simplest and most elegant way to do that is enabling the property replacement in the ee subsystem, as in the following example: <subsystem … Read more
In order to debug the Persistence Service in WildFly you can increase the org.jboss.as.jpa logging in order to gather the following information: INFO – will log information when persistence.xml has been parsed, when the persistence.xml has been deployed and when the persistence unit service has been stopped DEBUG – will inform you when Entity Managers … Read more
The Java Persistence API allows you to define multiple persistence units, each of which can map to a separate database. In order to use multiple Database, simply define a persistent-unit for each one in the persistence.xml file : <persistence> <persistence-unit name=”sample-db1″> <provider>org.hibernate.ejb.HibernatePersistence</provider> <jta-data-source>jdbc/SamplesDB</jta-data-source> </persistence-unit> <persistence-unit name=”sample-db2″> <provider> oracle.toplink.essentials.ejb.cmp3.EntityManagerFactoryProvider </provider> <jta-data-source>jdbc/SamplesDB2</jta-data-source> </persistence-unit> </persistence> In te above … Read more
By default the persistence unit are available in the java: Context. If you wish to make them available also in the global naming Context you have to add two properties to your persistence.xml configuration file: jboss.entity.manager.jndi.name gives you a transaction scoped entity manager you can interact with jboss.entity.manager.factory.jndi.name binds the entity manager factory into global … Read more
This is a handy cheatsheet for JPA developers with a collection of most common persistence.xml configurations.