The problem you describe is not handled by the database, and from my experience is not entirely handled by Hibernate either. You have to take explicit steps to avoid it being a problem. Hibernate does some of the work for you. As per the previous answer, Hibernate ensures that within an isolated flush the inserts, … Read more
The articles explains it. Clearing the entity manager empties its associated cache, forcing new database queries to be executed later in the transaction. It’s almost never necessary to clear the entity manager when using a transaction-bound entity manager. I see two reasons to clear: when doing batch processing, in order to avoid having a giant … Read more
I got bit by the org.hibernate.HibernateException: More than one row with the given identifier was found: problem and found no help on StackOverflow. It took awhile to sort out the issue so I’m documenting the solution here. I was using JPA/Hibernate and Spring Data. First off, this was not caused by duplicate rows in the … Read more
think works Criteria criteria = getSession().createCriteria(clazz); Criterion rest1= Restrictions.and(Restrictions.eq(A, “X”), Restrictions.in(“B”, Arrays.asList(“X”,Y))); Criterion rest2= Restrictions.and(Restrictions.eq(A, “Y”), Restrictions.eq(B, “Z”)); criteria.add(Restrictions.or(rest1, rest2));
Actually, according to the JPA specification it is forbidden to change a primary key: The application must not change the value of the primary key[8]. The behavior is undefined if this occurs.[9] (from EJB 3 persistence (JPA) specification, paragraph 2.1.4)
The code snippet you showed is what you need. Just use your existing configuration instead of creating a new one. If it is not you who instantiates the configuration (but, for example, spring), you’d need to extend the class that creates it.
I found an answer to this. The mappedBy attribute of @OneToMany annotation behaves the same as inverse = true in the xml file.
To sum everything (L2 cache and query cache) up: The first thing to do is to add cache provider (I recommend using EhCache) to your classpath. Hibernate < 5.3 Add the hibernate-ehcache dependency. This library contains EhCache 2 which is now discontinued. <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-ehcache</artifactId> <version>your_hibernate_version</version> </dependency> Hibernate >=5.3 In newer versions of Hibernate caches … Read more
Suppose you have an Order and an OrderLine. You can choose to have a unidirectional OneToMany between Order and OrderLine (Order would have a collection of OrderLines). Or you can choose to have a ManyToOne association between OrderLine and Order (OrderLine would have a reference to its Order). Or you can choose to have both, … Read more
It’s a bug, it seems that you can leave it that way and will cause no problem, but if you don’t want to see the message here are some solutions: (Edit: Option 2 seems to work better (see comments in this post)) 1.- singleSession configuration from DataSource.groovy https://jira.grails.org/browse/GRAILS-11198 2.- overriding the H2 dialect: public class … Read more