CRV2 RevCodePersistentAntiPatternJava

Java Persistence anti-patterns

Spring –Hibernate Lazy loading

This feature reduces the handling of data in an asynchronous way, which avoids unnecessary requests to the database, however it can causes problems with persistence. Errors associated with Lazy loading are:

org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect)

N+1 Select issue

This problem occurs when the collection is returned from the database, containing n+1 separate queries instead of a single join query. This issue is quite challenging to solve because it depends on the specific implementation of the code, therefore look for the following executions:

• Control that mapping configurations are updated for affected domain classes
• Add the @ManyToMany @Fetch(FetchMode.JOIN) as a query strategy to override the Lazy behavior if necessary
• Review Tuning fetching strategies from Hibernate reference (http://docs.jboss.org/hibernate/core/3.3/reference/en/html/performance.html#performance-fetching-custom)